Common Chevrolet TrailBlazer GMC Envoy Problems

In this video we discuss (and rant) common problems with Chevrolet TrailBlazer and GMC Envoy vehicles. Love them or hate them they are here to stay and driving (or being towed) to a shop near you! GM pulled out all the engineering stops when creating this special breed of SUV and we break down (literally) the most common problems with these vehicles.
Check out these other helpful TrailBlazer repair videos:
Water pump and fan clutch tips: • Chevy TrailBlazer 5.3L...
Crank Sensor Replacement: • Engine Cranks But Wont...
Upper and Lower Ball Joint Service: • Chevy TrailBlazer Ball...
Cam Sensor Diagnose and Repair: • Chevy TrailBlazer 4.2L...
Service Airbag and code C0550: • Chevy GMC Service Airb...
Hub Bearing Replacement: • Chevy TrailBlazer Fron...
HVAC compressor bypass hack: • Chevy TrailBlazer GMC ...
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[@Thomas-ul3uy]

I am a GM guy and I had read that when the 4200 engine was being developed, GM had the code name Atlas, before they changed it to 4200 Vortec. This engine was tested the equivalent of 300,000 miles at wide open throttle. When it came out, all the magazines said they like how smooth the engine was, the power and fuel economy was also on par for a SUV. I am the second owner of a 2004 GMC Envoy and I have over 235,000 miles on it and the SUV runs great. I have had to change the fan clutch, ignition coils, value actuator, starter, alternator and the transmission went out at 233,000. The miles this SUV has taken me and the expected maintenance is like any other vehicle I have owned. I have used AC Delco parts with the exception of the alternator. I let the dealership here put a new GM transmission in it. The SUV was in way to good of condition when transmission went out to scrap it and I wanted a transmission with a better warranty than a transmission shop would have provided. The leather interior looks amazing and the ride is still great my Envoy. I have had to do usual maintenance, spark plugs, brakes and again used AC Delco parts because the original parts had lasted that long. The owner before me had dealer maintain vehicle for them as well on the CARFAX that I had gotten when I purchased it.

[@jeffersonmartinez883]

One of my friend change fuel injectors the ignition coils spark plugs and even has like misfire

[@briansgamesandanime]

My 06 trailblazer is approaching 300,000 miles and I just now had a transmission put in. It's had an alternator and will now need spark plugs and coil packs replaced. Overall a very reliable vehicle for being almost 20 years old and nearly 300,000 miles.

[@shoafymusic]

@@briansgamesandanimeI’m really hoping to get 300k out of it. I bought it off my brother for $1800 and it only had just hit 100k miles!! He was tired of having to replace a bunch of stuff on it (prob due to age and wear and tear of being nearly 20 yrs old lol!) and I hopped on that deal right away. I’ve had to replace tranny lines, alternator, spark plugs, ignition coils, brake pads, rotors. Had to do front wheel hubs as well. All of it was relatively simple. I just recently pulled out my throttle body and gave it a NICE clean. We’re at 130k miles now and still going strong. Really hoping I can keep this thing for a good while.

[@lawandanix4621]

Brandon

[@Sara-xd2cj]

Why can't you live in my town?!?! You're the only person I'd completely trust working on my vehicle. Love your videos!!

[@dmh11185]

Thanks for the info...Gold. I was about to pull the trigger on a 2007 4.2 4x4, going with a 2007 4.2 4x2 now that you explained the front diff actuator.

[@pat2964]

Man it's so funny when you speculate what the person's feeling when they run into trouble that's hilarious and you're very thorough keep up the good work

[@ThecardoctorTV]

I try to be in touch with my customers emotions. hahaha. Thanks for watching

[@perezm714]

I used to live in Anchorage when I was stationed at Elmendorf. I have an '05 LT 4x4 with 105k miles. I've had to have the trans rebuilt, gas gauge, water pump, thermostat, fan clutch, spark plug coils replaced. I have a check engine light on again that I believe is the catalytic converter. The AC blows cold though! "maybe towing a 50ft 5th wheel, probably not" LOL Good video sir

[@aaronlee3233]

All these are spot on. At least us owners know what we are getting into. I've replaced all my front suspension, upper and lower a arms, hubs, water pump, and currently have to fix my heater core after I bypassed it cuz the plastic quick connect just broke. Being made of plastic and getting old, apparently this is common. Anyway, she runs great, you just gotta take care of your babygirl!

[@antiquegeek]

Wandered here just checking out what might go sideways on a Trailblazer that I am considering buying. Glad I stopped by- great info and the linking of your other vids to make it easier to find problem specific vids is great. You rant was well founded. There's almost always at least one thing on any vehicle that makes you wonder what was in their heads as they came up with that idea and that one is epic. Glad I found the channel - earned a sub for sure.

[@spakezarathustra9378]

Unbelievable depth and breadth of knowledge and experience, specifically on Trailblazer. Most valuable resource guy I have found for this vehicle. Wish he had something on power on at radio and CD, but no sound from Bose system speakers, no door chime, no OnStar, nada. But amp fuse is good.

[@mightysrk]

Awesome channel, you’re providing an invaluable service for free no less. Thanks for all you do and keep on keepin on!

[@ThecardoctorTV]

Thank you!

[@trevorjameson3213]

You have the best videos by far! Very informative and honest. A friend of mine has a trailblazer and it's two wheel drive with the 5.3 V8. He has had it for ten years and never had any major issues with it yet. It's a tough vehicle, being body on frame instead of these tin can uni-body things everybody has now days. I have an old first gen silverado half ton truck with the 5.3, which I'll never sell, I like it more than any truck out there and it just keeps on going and going.

[@ThecardoctorTV]

Thank you so much!

[@blackknight1906]

Very informative video. I don't have a lot of experience working on cars but I replaced my crank shaft sensor using your shortcut.

[@Meantime5]

Thanks Doc, I just bought an 07 TB with the inline 6 motor and although there seems to be a lot of quirks with this truck, most of them are minor. Now I know what to look for.

[@themrjones]

Thanks for making videos about the good old TrailBlazers.

[@Basshead40]

Best Trailblazer/Envoy video I've seen! Thanks! Saved this to my Envoy playlist lol.

[@ThecardoctorTV]

Thank you for watching

[@kristenmateo9156]

I have a 2004 Trailblazer. I only had a few major problems, my latest is the power steering lines. I'm in Southern New Jersey next to Philly, we get all seasons. I'm in the process of taking care of that. I do appreciate your time and videos, it has really helped me out alot. My truck is a 2wd 4.2L with about 128,000 miles. I have been noticing alot of sounds when I hit bumps and and just driving, possibly struts or suspension but it hasn't caused any problems. Thanks again.

[@MrSasquatch44]

I love your rants because they are all justified! I've had 2 blazers one with stuck crank shaft actuator inside the motor, AC problems and coil pack and potential ECM problems. I especially loved your frustration at the differential going thru the oil pan...what a screwd up idea meaning the whole front end has to be disassembled for some repairs.

[@KongDongLong]

No mention or rear upper control/trailing arm mounts rotting of the frame? Good luck finding a shop to fix those. Better have a backyard mechanic that can grab those up like I did

[@sovereignfreespirit]

Nice Find on that U-Joint Bolt Kudos! Glad you were doing this video or that could have gotten missed..

[@djentyman4002]

You seem to be a great mechanic! If I lived in anchorage, you’d be my car guy! Love the content, very informative and helpful!

[@ThecardoctorTV]

Thank you Scotty!

[@sharonstroka1645]

It was a joy listening to you

[@RhinoBenito]

I sure learned a lot about my trailblazer I'm able to fix them on my own now saved me a lot of money..Thanks Car Doctor

[@VictusMei]

Thank you. Your video helped me understand two issues that are throwing codes on my 2006 Trailblazer.

[@jasontippett6838]

I just bought an 06 4.2 4x4 for my son's first car. Its ridiculously clean, no lights, rides great etc. 180k on it. We're both really excited.

[@jaystangs23]

@Jimmy S if you maintain the oil. And dont abuse it

[@bigboardfun]

Great video thank you so much for sharing your knowledge.

[@BangBangBeefyMacNCheesy]

THANK YOU!!!! I’m about to take the plunge and restore my beloved 2005 Trailblazer! It been one of my favorites (and has just been sitting while we have several other trucks that work lol). But it’s that time of year again where I’m desperate to make this tank get back on the road and into the snow for some hard fun!

[@user-wk2ib4en5r]

great video very thorough snd easy even for a non-mechanic to understand;. as an owner of 2003 trailblazer with 92k I am glad i came across you. thank you for posting such a great thorough video

[@garym7771]

I wish this mechanic was closer to me, what a great guy and very helpful. Thank you sir for all your videos.

[@toyotaron7830]

Interesting video Doc, thanks for this. My wife bought a 2005 brand new and just traded it in with 105K on the clock. We did not have any of these issues, the only check engine light it had was for the AIR solenoid valve at around 90K miles, valve and gasket was like $75 and real easy to change. Was a Northeast vehicle too, we may have been ahead of the issues mileage wise but was always maintained. Happy Holidays to you.

[@freddyflintstoned913]

I would never let my wife buy a GM product. She loves her Sienna.

[@brentkendall7654]

Mister Berzins I don’t think he gives a shit what you’d let your wife buy😂✌🏽

[@ChadARoberts]

Thanks for the video! I just bought a Saab version with the 4.2. I appreciate you sharing your knowledge.

[@Mattman-ix8tt]

Thank you! I have a lot of these issues going on. Now I have the knowledge to repair them!

[@KX220R]

I just wanted to add what I found with code P0440 on my Saab 9-7x which is basically just a rebadged Trailblazer. I inspected my gas cap more than once and couldn't see anything wrong with it and then I would move on looking for something else to be at fault. Then one day I looked really close at the gas tank filler neck where the cap seal seats and saw that it was rusted. It wasn't rusted real bad but just enough to make it difficult for the cap to make a good seal. I removed the rust with sand paper and coated the area with a product called fuel lube and I haven't had another issue with it in two years. Fuel lube is a product used in aviation to lube valves in fuel systems so it won't wash away with fuel. I believe it has a bee's wax base if that helps anyone who is having the same problem.

[@ThecardoctorTV]

Nice tip!

[@nancydormedy8979]

Kevin Kirouac ni

[@jeffleach2668]

Excellent tip! I've had a problem with my sons Toyota Camry where the fuel cap will not screw on enough when it's warm outside. Works great in cold weather. I've used dialectric grease but it doesn't last long for obvious reasons. I'm gonna give this a try asap! Thanks!😬

[@TheOzthewiz]

Had a similar issue with my '01 cavalier. Kept getting 04xx DTC (small evap leak), checked evap purge solenoid and hoses, replaced gas cap twice. Found nothing wrong. I then did a close inspection of the filler neck, found what appeared to be a hairline crack in the ceramic at the filler opening. So what I did next was to remove the filler tube and pressure test the pipe with cap attached using water from a garden hose (red neck method). Sure enough, there was water seeping, not from the gas cap, but from the ceramic on the outside of the pipe. I replaced the pipe ($29. new on Ebay) and VOLA NO MORE 04xx code. I don't understand why that ceramic gas cap seat would crack on the inside, unless it was stress crack.

[@thomastommy1192]

Cool video very informative. Thank you for sharing your video. I hope you have a great holiday.

[@barrykruyssen]

Awesome vehicle review. I've just bought a 2003 GMC Envoy and am quite happy with it. The following issues were know when I purchased, but it is an old vehicle. It needs the fan clutch replaced (Fan roaring all the time) and the turn signal multi switch replaced (lights go on high beam when using right indicator). I'm also replacing the water pump while the fan is off. The one thing I cannot work out is how to adjust the drivers door tighter as it whistles at 100Kph. Thanks for the video, very informative.

[@johnrayfield2375]

I almost never subscribe to channels, but I sub'd this one. Your knowledge and delivery are spot on.

[@ryanlutton8193]

Love this guy! You have saved me so much time and $$$ over the years! Boy you aren't kidding about that curly hose under the resonator. Chased P0171 for 6 months, had it smoked twice, no leaks. Replaced the hose, P0171 came back after a month or so. Hose clamps solved it permanently. Keep up the good work, you are a no BS straight shooter!

[@oscar5243]

which hose had you replaced

[@mikepowell8958]

​@@oscar5243it's about a 3-inch hose under the resonator ( the black plastic box on top of the motor).

[@j.j.s.jr.5136]

Great video my dude! Very informational. Thank you for your expertise!

[@darrellcrawford3912]

Well spoken

[@briannpatricia9772]

Thank you sooo much for sharing your knowledge!!! Every video is EXTREMELY helpful!!! My 2004 Trailblazer is running GREAT again!! Thanks!!!👍🏻👍🏻

[@bbolck27]

Brian N Patricia ã

[@artificialdopamine6542]

What did you do? Coils?

[@billlutz6019]

Thanks for the video . Had a appointment to go look at a low miles 2002 envoy tomorrow and talked me right into canceling that. ;)

[@bandittweintraub]

Left out the Headlight issue, where the relay fails randomly. I have had that in my 2007... but there was a TSB on it, and GM fixed it for free. Actually, my Trailblazer has been more reliable than my wife's 06' Impala.

[@ericgrimes2608]

After owning my 05 for a little over a year I'm now having... 1: a knock 2: torque converter not locking 4th/od 3: oil leaking where the front dog goes thru the pan 4: intermittent slow start (occasionally it actually fails to start, or starts slowly and then revs up and STINKS of hco's) 5: airbag light SOMETIMES And I have replaced the plugs, coil packs, cam solenoid, trans shift solenoids, rear sway links and bushings, and soon the front links too. Oh and another thing I just got the part in today, the heater blend door actuator. It wont change blower settings and just clicks forever. I got by fine thru the summer but its cooling down and I'm starting to need the defogger lol. I've owned about 6 different cars, 2 of them chevys.. 3 were fords and one a Nissan, and I have to say, the chevys I've owned were GARBAGE. Always presenting me with a new repair. Alternators, fan motors, powertrain issues GALORE. My mustang, Taurus and Ford contour hardly ever gave me any issue at all except maybe a battery and some end links every now and then. Also I trained in a GM focused auto tech degree, and worked at a GM dealership (Buick and GMC, but I saw a lot of chevys too) as a mechanic and can tell you no matter how good you treat your GM, it's going to quit on you more often than not. My sister in law has a GMC Acadia rotting in her driveway because it wont run or start, it was just ping ponging this problem to that problem until they gave up. It's out of warranty and they're paying for a car they cant even drive, mechanics cant find the problem.

[@brendenreed9997]

Started watching this video to get an idea what’s going wrong with my 06 trailblazer, and the very first problem you talked about is exactly what I think is going on with my car. Got a cam shaft position sensor code and I think this might be the fix! Thanks

[@tonyjohnson8388]

Great video! I definitely would have mentioned about the exhaust manifold issue. Notorious for cracking! Design flaw. No room to flex.

[@artificialdopamine6542]

Yesss!! Mine has been cracked in half for ovee a year

[@187WCB]

I was following one of these on a highway once and its engine caught fire and smoke was billowing out. The teenager driving it wanted to keep going after i got her to pull over and put the fire out. Nice safe ride for your kids.

[@ThecardoctorTV]

Oh my. Haha.

[@paulg444]

This guy is simply one of the very best mechanics on youtube. I love this guy, he is so knowledgeable and has a great sense of humor. Im laughing my ass off!

[@mikeatv]

Paul G ... your right.... this guy is one of the best on here...

[@fadumpt]

"Maybe you're towing a 50 Foot 5th Wheel...probably not" I mean....5th wheel maybe...with the right adapters...

[@kristineward3893]

/ccgvvu

[@nslouka90]

You haven't seen the car wizard

[@TheOzthewiz]

@@nslouka90 The WIZARD is MUCH better, without the "echo chamber" acoustics due to poor mike set up.

[@silentj3]

Straight forward and no b.s. helped me with my envoy 4.2 thanks for all the info👍

[@StayPositive-sd8op]

This is the best you tube video! You get detailed and right to the point...I got a 04 Envoy and my inside lights never go on except every 6 months they will light up sometimes a day and sometimes a week. I gave up trying to fight with it

[@geekynewz]

Thanks for the great video! I'm a GM tech, I remember when these vehicles first came out. The straight six was new and this was prob one of GM's first drive by wire cars.

[@quita705able]

geekynewz could u tell me where the heater core is located on a 2004 gmc Envoy

[@kristaletendre9576]

I have a 2002 trailblazer and my front wheels wont lock into 4x4 can anyone help

[@ThecardoctorTV]

The video talks about this. You may have a differential problem. Probably should take it to a qualified repair shop for inspection. Good luck.

[@ThecardoctorTV]

Behind the glovebox area

[@derrickodyes1934]

geekynewz 6.5 turbo diesels had fly by wire since 1994

[@johnmcfarlan3672]

Excellent video. Interesting to see the common problems. I had a 2003 TB and out 480,000 miles on it before writing off after I got rear ended. I only had a few if these issues - evap leak gas cap, thermostat, hub bearings. Trans went at 250,000, rebuilt for $2000. I broke the front diff , had a shop replace it with a used one for about $1500 at about 265k. After it got written off I bought a used 08 Envoy. I LOVE these trucks! Perfect size for my needs, comfortable, decent enough gas mileage. I also had a Canyon with the 3.5, 5 cylinder, and liked it too! No engine issues with any of them.

[@lethargicstove2024]

What gas mileage were you getting

[@johnmcfarlan3672]

19-20 mpg US gallon

[@lethargicstove2024]

@@johnmcfarlan3672 that's better than I thought I was expecting 16-17 mpg

[@josephalfonsi8022]

I have an 07 TB 290,000 and my gas mileage is about 13 mpg runs great burns about 1qt of oil at the oil change every 3 months

[@mikepowell8958]

​@@josephalfonsi8022I have a 04 Trailblazer with 180,000. I was getting 18 mph until I got a small evap leak. I thought that when I found the filler tube rotted out and leaking, replacing it would solve that but it went from a small to a large evap leak. SMH. Now I'm getting 16.8 mph. With the large evap leak. It doesn't burn any oil. Yours may have been one of the years that had bad exhaust valves.

[@karlschwab6437]

Enjoyable watching you with the Chevy Trailblazers! My 2002 at 130k miles, just lost it low beam headlights. Swapped relay (modules) 46 with 45, and no joy. It is so cold now in Michigan, guess I'll try and put it off a bit longer; no garage of my own. Thanks, keep 'em coming!

[@mikepedersen9520]

Only one relay does headlights. Replacing both is unnecessary but obviously doesn't hurt

[@mquigglez2417]

This gave me a lot more information on the Trail Blazers my mother has one and my father has another one as a spare vehicle and I'm always having to replace things and we've had some of these problems come up now I know how to go through some of it one thing he didn't mention is the rear trailing arms and brackets especially if you're driving in a place with snow or in the Rust Belt and the place with high humidity they rust right out

[@theSword-]

Dude, I love ya man! You're an honest guy, and a great mechanic.

[@karlackdamack4238]

One of my favorite channels.

[@ThecardoctorTV]

Thank you!

[@nrrobamsnr7294]

sir thank you for the information. here in Philly not enough mechanic s stay in top of it like u do.

[@15rlinton]

Working on misfure codes right now!! This video and information was very informational!!

[@dirkayala5812]

This is awesome, Thanks! I just took chance and picked one these up yesterday('04 Envoy), and those lights were on. Plan this morning is to change oil so I know that's done but looks like this could be what I'm looking at so Really appreciate this...Subbed!

[@TechTimeWithEric]

I was told by someone who worked for GM that the reason they did the differential through the oil pan was to help with the center of gravity. I own an 04 Envoy and based on how it handles, I would say they were probably right.

[@MikeNielsen1147]

Thank You Sir for this video!!! I have a 2005 GMC Envoy with the same motor. A bit over 220k miles. And am having miss fire issues as well as a couple other things You very Well highlighted here for me.. Much Gratitude for importating that wisdom!!!

[@mocajoe2820]

Great video for my TB. Thanks Tim.

[@nitraml4536]

We have a gmc envoy that the clock spring went out because they change the rack and pinion and the steering wheel turn on them but freaking clock spring is 400 dollars at the auto parts We decided to get the whole steering wheel at the junk yard and only cost 55 dollars and the clock spring works great now

[@RebALGaming]

And that is why I run the seat belt thru the steering wheel and buckle it when I do rack and pinion jobs. Saves me and my customer the headache

[@nitraml4536]

Reb AL yeah I do that too

[@donniecreasey7722]

Reb AL my mega fuse keeps blowing in my 03 envoy any ideas

[@keisongz]

Thx you so much I have a 2003 chevy trailblazer ent my fav car with 130.000 miles trying to keep it on the road

[@ThecardoctorTV]

Thank you. IM sure youll get plenty more good us out of your rig as long as you treat it well. Thanks for watching

[@waltersmart1824]

My 03 has 248k miles on it ! Drive it everywhere!

[@kyleblackmore99]

my 03 jest hit 300k and still works well but it bounces like a bouncy ball still fun ride

[@sharonc.cooper9367]

I think your KZbin's best! I'm just sorry your not closer to me. Thank you sooo much for your very much needed videos. Hey, and you do have a great sense of humor.

[@ThecardoctorTV]

Thank you. You can always drive up to see us. Its worth the trip!

[@margaretellis1508]

Thanks for this video I just got a TB and I been trying to make sure I got a good TB and now I know I only need plugs and core stuff thanks

[@RingZero]

Great video, I have a 03 EXT model, nothing major so far for 15 yrs. replaced rack, trf case electric motor, usual brakes, water pump and thermostat. Good value for money if you maintain them well, great trucks.

[@lucycarin]

Oil_Burner good to know, my son just got one ....👊🏼

[@fargeeks]

That is true but lately ive been informed basically that maintenaning them isnt an easy process especially how whatever part the vehicle needs are hard to find Ive been told that the instrument cluster needed replacing as it was acting weird and come to find out that finding a new one for my ascender was not possible so they found one off of a trailblazer and so far everything works properly however i do not have a messege center and the button on the steering wheel used fir interacting with it do not do anything, so all i get is just the mileage and nothing else

[@MrBane213]

One that you forgot is the fuel leveler/fuel pump. Great video though. As a 2007 tb owner, I’ve had to deal with half the things you mentioned.

[@piccolopeter]

did you have problems with an evap code??

[@ayyye9459]

I'm going thru it right noe with the furl leveler.... Put my truvk on thr side of the road 3x!!! Now i dont let it get under a quarter

[@mikedobro2838]

Unfortunately there was a recall on this which expired and I now have to use my odometer to count to300 miles to know when to fill up.

[@jessesiciliano7657]

@@mikedobro2838 you get to 300? I was told around 220. have an 07. went to fill up today and filled up half a tank. I gotta get it fixed. don't wanna play the gas guessing game anymore. just bought the truck.

[@mikedobro2838]

@@jessesiciliano7657 I was told it would cost big bucks to replace fuel sensor. The gas tank has to be removed and the sensor is expensive

[@chrisconrad6014]

Love your videos you taught me a few things I never knew thanks doc

[@1gofastboat327]

Great video pal , I love my 03 but here in ontario Canada with the salt we use on the roads we have additional issues . Keep up the good work my friend.

[@Gene4God]

One thing you have forgot to mention is the lose of power due to the throttle position sensor this is extremely common in the Trailblazer and the GMC Envoy , Many people replace the whole throttle body when all is needed is to replace the sensor on the throttle body . Other than that great job Sir !!! So if power is lost when turning on fan for heater or AC most likely it is the throttle body position sensor and a easy fix . But I also agree the Trail Blazer and Envoy are badly designed. Love my 98 S10 4x4 extended cab :)

[@MIKEROADDOG]

And exhaust manifolds crack

[@deborahbattleson2226]

Thank you for adding that comment. I just ordered the whole throttlebody unit with the sensor in it, for my 2004 as I didn’t want to take it apart and it was only $20 more for the whole assembly on Amazon. We’ll see if it fixes the problem! I’m currently losing power when the air is on and also going from 2nd to 3rd. I have no error codes other than P0128 for the coolant thermostat.

[@RetroCaptain]

​@@MIKEROADDOGThe reason is the factory had mistakenly ordered "too long" manifold screws (both sides). After a few years an excess clearance develops and to resolve it the correct length screws must be swapped and at tension. Most owners "ignore the noise" (of the rattling manifold) until it finally fracture into sections. The intake side sucks in air causing error codes.

[@mikepowell8958]

​@@deborahbattleson2226I was having the same problem with my thermostat. But even though I thought the throttle body was causing the power loss, it was caused by the thermostat telling the PCM to run the fuel rich. That in turn was causing the catalytic converter to clog up. So the Cat clog was causing PCM to run the wrong fuel mixture creating the low power. And that made the transmission not shift correctly at times. And I never even had a service engine light come on until the truck lost so much power it wouldn't go over 20 mph. If I had just started replacing parts I thought were causing the problem, the last thing I would've thought of was the catalytic converter. But really it's all the electrical systems being connected together. And if one system has a problem, it signals all the other systems to run incorrectly. What a nightmare but I still love this truck.

[@greggbowers1947]

Really comprehensive video! How much different would you say this is from Envoy? They appear identical

[@michaelwaller8252]

They are, other than the front and rear bumpers and fenders!

[@terencescott3957]

I never had to worry about having a bad variable valve timing solenoid. I busted mine off while changing my water pump. :):) So it's only a few years old. Very impressed with the Envoys despite all the common problems. Mine will be turning 15 in a month.

[@stopnwatchentertainmentjdt9325]

The exact issue im having at 10:00 mins ... Such a blessing thanks dude ive been struggling trying to figure it out.. I thought it was the alternator but after weeks and months of driving it only has stalling and start up issues.. If it was a competed alternator failure the truck wouldnt run at all.. I get electric shock when i touch the door sometimes.. Im betting its the fan clutch and voltage circuits... Or the pcm

[@Treppiede]

Helping a neighbor with their Trailblazer. Thank you for this video. Here are some spots in the video that might come in handy: 1st: 1:30 P0014 2nd: 4:00 P0440 3rd: 4:50 P0340 4th: 5:30 "Service 4WD System" 5th: 6:13 Misfiring (P0300, P0301 CEL possible, ignition, injectors, MAF) 6th: 8:30 Water pump, Fan clutch, voltage reference, crank sensor 7th: 10:52 Not coming up to temp 8th: 11:43 "Service Air Bag" 9th: 14:18 Front diff (possible "Service 4WD System")

[@ThecardoctorTV]

Sounds like everything between 0:01-the end credits might be helpful here. Haha

[@joea4279]

what about all the Electrical issues ? Tailgate, traction contol ,Etc . Maybe you can do video on these issues ?

[@jimmantel6494]

Replaced starter new battery still won’t start!

[@debbievian6430]

Appreciate you so much. I have a 2003 4.2 litre trailblazer with a problem of overheat . About 200 on temp gage. Go 10 miles in any weather over 40 degrees and it will not start, unless it's given half hour to coòl down. We have replaced numerous things but wonder about thermostat. Also high use of fuel . Thanks for any help. Thank you! Have a great day! Your the best Car Dr!!!!

[@anarchistangler]

Yeah, totally peaking out about the water pump. It's a very helpful video. Just too funny not to mention.

[@marshalllaw2865]

Had to replace the rack in my 09 tb. Also water pump and clutch fan, fuel pump. 225,000 on the clock and still runs good.

[@fishfire_2999]

Good to know 👍

[@kidmystery2010]

Where did you find an 09. That latest I see is 08

[@PresentedByBailey]

#5 should be#1. i had an envoy and switched to trailblazer ext and my dad has an envoy and all 3 have had ignition coil go at around 100k miles. my dad's had the crankshaft sensor (iirc) and power steering pump go at different times. all 3 had the inline 6. love that engine! at 100k miles i did a bunch of preventive maintenance items myself on my trailblazer and it was fairly easy because of the room the inline 6 gives you to work on it. i did water pump and decided i might as well do the fan clutch and decided to do the alternator and while in there might as well do the thermostat. that might be it but it was only 2 or 3 hundred bucks for the parts. i'm no mechanic and it was doable. i did my dads steering pump as well. i'm handy but no mechanic and it was doable. these vehicles have 4hi, 4lo, 4awd and 2hi... love 'em.

[@dawsoncravens8625]

Sameeee

[@cameronashley2881]

Bet that was a hard one to troubleshoot, with multiple cylinders misfiring

[@lethargicstove2024]

Would you recommend it

[@UTINNI_36]

Just picked up a 2004 envoy 4.2 vortec ya!!

[@Poopbagsteve]

@@UTINNI_36 how do you like it? Anything to look out for?

[@saxologist1]

I was just about to but one of these. 2002, original owner with 174K miles. The owner was telling me that she had changed the water pump and the mechanic had to take the frond end apart. I'm glad I ran into this vide. The mechanic is awesome and he changed my mind about buying a Trailblazer.

[@robw3027]

Very useful rundown. Like the delivery- straight and to the point. Will subscribe. Have to say though I would not touch a Trailblazer useless no other choice. They have a rep for problems, video sure confirmed that. I currently drive a 01 YUKON 4wd with a 5.3- only because it was the best bang for the buck mileage and condition wise at time of purchase. In future won't touch a Chev, that is not at least old enough to have a 350 in it. Thanks again.

[@eiserntorsphantomoftheoper2154]

Wish I had a mechanic like this dude....

[@bigh8121]

Ty for taking the time to share your knowledge. People don't take the time to appreciate how youtube changed our lives. Videos like this brings this truth to bare.

[@golfmanmatt]

Seriously, having to buy a Chilton/Hanes manual for every car I ever owned started to get cumbersome. Appreciate The Dr. passing on all his knowledge.

[@ginaberrie2608]

Agreed, the knowledge people share has been a life changer. It has helped me learn to work on my own vehicles. I just picked up an Envoy last night and I can't get this thing to start all day today. The car does nothing when I try to start it, there is power in the battery, seems kind of like an anti theft issue. Car did not come with a key fob. Thank you Tim for sharing your knowledge, much appreciated sir👍

[@braydenthompson8352]

Thanks man. You are a scholar and a gentleman with a bad ass sense of humor. I'm in montana so were practically neighbors haha..

[@paulmoffat9306]

The number one issue that I had with my 2003 trailblazer, was transmission failure. I had to have it rebuilt 2 times, for the same issue - water was getting in the ATF, and it turned out, that it was a KNOWN defect in the design; In heavy rain fall, the drainage from the windshield can cascade onto the transmission fluid fill tube, putting water into the oil through an un-sealed dipstick. The factory fix was to change the position of the tube, and change the dipstick design (simple). When the rebuilt transmission failed for the 3rd time, I had enough with the dealer's rebuild, and went for a Jasper re-man. No further issues.

[@cepuras]

Even the oil filter is a pain in the ass to change.. the people that are responsible for tool clearances during design phase that allow this should be hung.. been through most of the misery you have listed.. great video.. cheers!

[@rosaazul88]

I had a jimmy that was older and gabe me less problems!

[@chrisbetancur453]

I had 2 Jimmy's and 1 Blazer. Way more problematic than my TrailBlazer. Less power, less efficient. Only thing they had going for them was that they were more comfortable. Specially my Diamond Edition Jimmy (precursor to Denali's).

[@richardsmith9271]

Hey I bought a 2000fwd about 3 mo. Ago, so it's good to know what to watch for about some things and what I can't fix, I have a very good and reliable mechanic that I can rely on!

[@Nickadoo500]

Very helpful video as am i replacing plugs on a friend's 04 Trailblazer EXT w/ the 4.2 L6. He told me it had a misfire, so expected bad coils along w/ bad plugs. Plugs were terrible, and the electrode trip coming out of the center of the spark plug was worn down to a needle point on all 6 plugs, so i replaced them with AC Delco 41-814 plugs. It had Autolites in it. I think the misfire was coming from the #4 cylinder, seeing that the plug was covered in oil when I removed it. I just hope that it is only bad plugs and one bad coil and hopefully nothing major like a blown head gasket or bad rings. I doubt the rings are bad since the motor is only at 222k miles, but hey I ain't no mechanic, I'm just too cheap to pay others to do work and I have a little "Napa know-how". Say, does anybody know if these GM 4.2L motors are susceptible to blown head gaskets?

[@TheProfessionalAmateur91]

Epic video sir!! Very informative. I love these vehicles. On my 2nd one.

[@ThecardoctorTV]

Thank you

[@Getyourdoe]

@@ThecardoctorTV So overall would u say a 2008 Envoy is a good or great vehicle, or should I save my money and buy foreign, Toyota ???

[@scottymonochrome3795]

@@Getyourdoe I'm looking between an '08 Envoy SLT (75k mi for $8500), '09-'11 CR-V EX-L(found a 50k mi example for $9k), and '09-'11 RAV4 Limited(24k mi rebuilt for $9k). I can talk the Envoy down to $6-7k all day long. But I know it's almost halfway through it's life. The Honda's/Toyota's however, are barely broken in. I've worked for Toyota, I've owned GM products, I own 2 Honda's right now, a Lincoln, a Chrysler, and a Chevy. I'm still deciding, but I'm going more towards the Asian Market CUVs

[@paddle_shift]

In 2018 I bought a 2005 TB that had a little over 55k documented miles (I confirmed with the carfax and the dealers who did the work) for $6700. I thought at the time wow what a steal! It was! For the dealer! I have put in over $4k repairing a stall problem that does not go away. You name it, it likely was replaced. Your comment about the water pump magnetic clutch sharing the same circuit as the crankshaft actuator is probably the reason. You do note that this magnetic clutch problem causes weird electrical codes matches exactly my symptoms. What would you charge me to come to dallas to fix my problem? It may be worth it for me.

[@michaelwaller8252]

That means that the mechanics that you have been graciously been funding their grandkid's college fund DO NOT know what they are doing!

[@tlcbear2]

nice wish would of had a video like this before i got the one i did lol but its been used for videos and will be good when i am done.

[@ThecardoctorTV]

Yes they work very well for Videos. Haha. They are pretty good for driving too. Blessings!

[@freddyflintstoned913]

Read Consumer Reports and you would have never made a purchase like that. Get informed.

[@buckstr978]

....very good video... my son is bless with a 2003 Trailblazer and we just did the dance to track down a large draw on the battery while parked... turns out it in the alternator... we plan on swapping out the thermostat as he has a overheat issue at slow speeds.... runs fine at highway...I did chuckle at the crank sensor and VVT sensor as we have had to replace them... and the fan clutch... good to know we are not unique... :D

[@KlyfflovesShelby4ever]

Thanks for the videos just got a TB and have these issues myself

[@georgewiebewiebe9137]

This guy is doing a great job, from my experience GM is full of problems all together like nothing else.

[@TheOzthewiz]

Not just GM, but ALL American vehicles have problems. Next time just get a TOYOTA, problems solved!

[@dennishassler605]

Cars are becoming more complicated, so you may be best advised to buy an older model - many mechanics say they are BETTER. I have a 2001 Suburban with 300K and it's been trouble free and doesn't use any oil at all. The newer models are more complicated and change is not always good. Try to find something with a gentle history and synthetic oil is a MUST.

[@interstate5trucker]

The only Toyota I’ve ever owned was a 2009 Matrix. I bought it new and owned it 2.5 years. The water pump failed, the battery failed and there were several recalls. Toyota is no better than GM.

[@roninkraut6873]

Bold Venture Toyota is a little better than GM but all vehicles have some issues. I’ve had a couple of Honda’s and they’ve been one of the worst with wheel bearings, electrical, etc.

[@michaelwaller8252]

Chrysler body control computers are worse, and fords nowadays are nothing but JUNK IMHO!

[@LaramieJim]

They put the axel through the oil pan! Engineers must have been smoking good pot. Like in the 70s the made plastic coated timing chain gears!

[@151bradhatt]

Laramie Jim yeah I figured this out when I changed the engine in mine

[@crackertroy]

Is this on all Trailblazers or just the 2002?

[@151bradhatt]

@@crackertroy might be all with the 4.2 liter motor

[@crackertroy]

Brad Hatt thanks my neighbor is borrowing mine now I will look when I get it back

[@warrenlancaster8045]

crackertroy 2002-2005 are the exact same. 06+ have a few differences. 06+ engines actually have a different cast number completely! This new engine was technically “bulletproofed” from factory. 06+ engines had grooves cut around the cylinder bores and copper rings were pressed in, creating a small raised lip, to greatly improve head gasket seal. The new models also had slightly bigger crankshaft bores to fit thicker main bearings to combat possible crankshaft walk at high RPM. 02-05’s coolant temp sensors were located right under the thermostat on the drivers side. In 2006, GM’s redesigned 4.2L block had this sensor relocated to the back passenger side but keeping the same part number. 06+ also had an improved camshaft profile which increased its valve duration and lift allowing for better fuel mileage, a slightly higher redline, and an increase in overall power. The first group of trailblazers were fitted with aluminum alloy connecting rods and pistons that were prone to cracking, blow by, scarring, and knocking. The new engines had a set of high quality, pure, balanced, forged aluminum rods and pistons (hyper-eutectic). These are stronger, lighter, dissipate heat quicker and more evenly, and slows the build up of carbon on the piston face. 2006’s and up also have a completely different engine tuning as well as a different PCM, ECU, TCM, TCCM and BCM than the earlier models. Also starting in 2006, the Vortec 4200’s cylinder compression ratio increased from 10.1:1 to 10.3:1. Both changes in the camshaft profile & compression ratio resulted in an increase in horsepower and torque. 2002-2005’s saw 275hp/275tq and the 06+ saw numbers of 291hp/296tq and had it available 200RPM sooner. The 2009 year, which not many were sold, the RWD 4.2’s somehow made 303hp/307tq.

[@76calidude]

Nice! I'm on track with my 07.. Phaser Solonoid...Full Ball Joints..Water Pump...Viscous Fan Clutch...Blower Resistor...although he didn't mention the wire chaffing inside the loom where the back hatch flexes..causing me to get locked out. But love my TB!!

[@Clare.1985]

was just about to end up with a 2008 trail blazer with 138k looked in good shape except the under carraige was rusted a good bit. but now after watching and listening to everything you had to say. No way. thanks man.

[@MrPami9899]

Make one on the explorers, since they are similar vehicle, thanks for tips tim

[@lynndempsey4096]

STEEVE DAVID Nicolas 248 thousand miles no problems.

[@bstceltics4]

Explorers common problems. - Transmissions are shit around 120k miles they will die - Coolant pipes are a wierd plastic material that gets very brittle ane breaks - rear hatches crack not sure why but they all crack lol - rust...everything rusts really bad like a pick up truck - MAS air flow sensors - the heat to AC blend door actuator behind the glove box - bushings...very squeeky bushings lol As far as thr motor goes the v8 is the motor to have 4.6 or 5.0 they are good motors everything else on them not so good

[@sanjuan780]

How do you do all those relearns you mentioned? Thanks for a great video.

[@MrMorbugs63]

you have to use a mechanics OB11 reader like snap-on or something

[@chriscurtis8344]

Is there a DOCTOR in the house! Yes, there is! Thanks, Car Dr. Not only you know your stuff. You seem like a d@#% cool guy! We appreciate you. In a bummer dealing industry, it's refreshing to see an expert like you who cares!

[@InfiniteCheeseCrates]

Good to know about the injectors, having missfire issues with mine at the moment, but if that doesn't help I'll know to check out the injectors.

[@michaelwaller8252]

Mine currently has a misfire on cylinder #5 because the valve cover o-ring around the coil pack hole is leaking oil into that cavity and grounding out the plug. I'm in the process of ordering the valve cover seal set, as well as 6 new DELCO OEM spark plugs and 2 new coils. I don't think I need the coils, but I'm going to have them in case I do need them when I tear it down!

[@fishfire_2999]

Enjoy listening to mechanics that know what their talking about 👍👍Now where to get a decent code reader that wont break the bank 🤔

[@OtherworldlyTV]

Who are the suspect ones🤔

[@fishfire_2999]

@@OtherworldlyTV Good question.

[@skiprope536]

Here is my list..Chatter torque converter, skylight weep holes clog, whippers will not shut off, cab lights dim when running on battery, front end all components, speakers not working... Other than that I love it. Best SUV ever owned. I got a GMC 2005 Envoy gonna dump 3K into the front end...I also gotta drop my front differential and rebuild. Seals are leaking. 250K I think i can get one more 100K out of it. NO Rust and looks great.

[@Barbaratio]

I need to drop my front diff and rebuild it as well, how or what did you follow in terms of rebuilding the differential?

[@michaelwaller8252]

At 250.000 miles, you have NOTHING to complain about!!!!! Now, if it had less than 100,000 miles on it, that would be a different matter!

[@kevinwhoriskey8150]

Great comments and some sound advice.keep it up.

[@ThecardoctorTV]

Thank you!

[@claudiofagundes9502]

A friend of mine had one of these years ago with the 4.2 his transmission let go on him and he decided not to have it repaired because supposedly it was a $2,700 transmission at a junkyard plus labor and from what he said its a common problem with the Trailblazer wanted to see if this was true but it was not mentioned in this video. Good video I learned a lot I am now subscriber to this Channel and look forward to more videos like this

[@michaelwaller8252]

That price was totally absurd for that transmission! It's the same transmission that is in all of the early 2000's suburbans, tahoes, s-10's colorados, canyons, and half ton sierras and silverados! A good transmission shop can take the old trans out, replace EVERY MOVING PART IN IT, and reinstall it with a TWELVE MONTH warranty for under $2000 !