Cooling Fan Stuck-On Case Study: '04 Toyota Highlander

[@raymondcascella4920]

Very few people out there that are determined to fix a problem like this and then to share it, gives me hope that there are still some honest hard working mechanics. Cudos to you.

[@PineHollowAutoDiagnostics]

Thanks Raymond! This was a neat case study :)

[@motohead3214]

A 20 year master tech just want to thank you, have the exact same issue you saved me time and the customer money, I have never seen a short through the connector bit sure enough that was the issue, I had the junction box all apart and still couldn’t find the issue, thank you so much for sharing!!!!!!!!

[@PineHollowAutoDiagnostics]

That's awesome! One of the weirdest electrical failures I have ever seen on any car! 😅

[@johnchristensen4665]

Well, I still have a 2004 Highlander and it did exactly what was described in this video. Once I pulled the blue/white wire, the fan stopped running. I went through all the checks that was described here and was amazed that my problem was exactly the same as described. I would never have found the problem without this video. Good job tracing this electrical anomaly.

[@DeRanged218]

What did you do after you pulled blue/white wire? Just “cap” it off?

[@randygudeahn7304]

great detective work Ivan. you and Eric.O have taught me to never give up on a repair. I'm an appliance tech for a very lage company for 27 years. going out of the box to watch you both in another industry is amazing. Different field, but same work ethic and diagnosing procedures. I thank you and Eric.

[@PineHollowAutoDiagnostics]

+Randy Gudeahn (ProTech) Hey Randy you are absolutely right about the diagnostic procedures and thought process being very similar. Most modern appliances are all logic-controlled and programmable just like cars! I had to troubleshoot our house heat pump a few years ago. It was throwing trouble codes (!) for the outside air temp circuit...turned out to be a bad thermistor. Can't imagine how expensive a diagnostic/repair house call would have been on that thing!

[@Okie-Tom]

Wild, I just watched Eric O have almost the same problem on the same connector on a Toyota! His were all crusted together. He had to completely take the connector out of the wiring. Good investigative work Ivan! Tom

[@stuzman52]

Who in their wildest dreams would have thought those two wires were shorted together inside the connector. Great work Ivan with the diagnostics!

[@PineHollowAutoDiagnostics]

+stuzman52 I couldn't believe it either, Terry! Thought my Ammeter was lying lol

[@felixcat4346]

He fake it. Its the youtube "McGuffin", a "McGuffin" is the excuse to make the plot swing, don't matter if its true or false. Show biz 101.

[@scottwarren8847]

@@felixcat4346 stfu dumbass

[@billrimmer5596]

Ivan, that was excellent!! The three things that really helped me in this video were 1. Your use of the incandescent test light. 2. The ammeter clamp on probe. 3. Your skills at interpreting the signs. Also appreciate your BBB comment in answer to a fellow subscriber. Class was very good today!!!

[@froglegs4910]

He did good job for tracking the problem ! very clear explanation !

[@jerseysaltfisher]

Awesome video..mechanic myself all my life, 25years, and consider myself very adept with electrical problems like these. Great methodical thought process and great use of following wiring diagrams and using testing equipment..enjoyed watching

[@ManicMechanic007]

Intelligence + determination = win. Great work Ivan.

[@yloow2]

I thought that you had lost your mind when checked amperage on the dead end of that connector . VERY GOOD JOB !!!!!!!!!!

[@mmichaeldonavon]

Ivan. IMHO, superb troubleshooting! You and Eric O are killing me! I never knew just how much I did not know about troubleshooting cars - I'm learning, thanks to you and Eric O. Many thanks for the "Heads up" with BBB Industries - now a member of their data base. Many, many thanks.

[@nicholasmichalek1227]

Just did a customer's car with the exact same problem. This was extremely helpful. Thank you.

[@ciankilduff7992]

Hey there! I currently have the same problem. Did it end up being in the connector pointed out in this video/was it fixable? Praying it is bc I just put in a new battery and alternator just to find it still has a parasitic draw. Thanks in advance

[@mechtechtools77]

That was a crazy diagnosis. Who would have thought shorted wires in connector. I bet most shops would have thrown relays and a computer at it. Awesome job!!!

[@PineHollowAutoDiagnostics]

+buzzerauto Yup that situation could have gotten ugly with parts swapping...good thing they stopped at just one relay!! Hopefully the computer driver for the fan relays survived the short. Maybe should have bi-directionally checked it?

[@mechtechtools77]

+motoYam82 Maybe but I sure there fine. I guess you should always verify repair. I've had connector issues on stuff but I usually find green corrosion or damaged connector. But this video shows that there doesnt have to be anything visual to be a problem.

[@saaaron5213]

BBB you broke my heart..... No more wiring diagrams -- I wish I could find another site, but so far no dice.

[@thomasmorris206]

Thank you ! , I just encountered the same issue with an almost identical vehicle.Your diagnostic work saved me hours , furthermore the problem could have led to some other expensive potential solutions as there was absolutely no evidence of a problem with the connector on my vehicle . Nice work & thanks again!

[@ashley_stephenson]

My Toyota has the same exact wires and issues you did! So weird!! Thanks for the video wouldn’t have found it without your video!

[@QuiteDrifty]

Holy moly dude! Just finished up my mom's Highlander. It was literally this exact same issue! Even the pin broke off as well! Thanks so much for posting this, honestly not sure I would have gotten it myself.

[@PineHollowAutoDiagnostics]

NICE! I thought no one would ever find the same problem as here. Good thing you didn't take it to a shop and watched KZbin instead ;) P.S. If I helped you save a bunch of money feel free to click on the Fan Funding button too. Glad I could help!

[@moonsynth]

Thanks for the great vid. I started out with the same cooling fan problem. Later in the day my car started stalling at idle. Instrument panel was going crazy. Trans would skip when I turned on ac. I had one of the pins in the same connector come off when I opened it up. I ended up bypassing the connector with 4 sets of wires over a couple days and everything is great now! Thanks so much for the thorough diagnosis and education in electrical troubleshooting. Great wiring diagrams and info at website you mentioned. Way better than Haynes manual. Thanks again.

[@PineHollowAutoDiagnostics]

That makes my day! Great job on the repair, hopefully your Toyota will be problem-free for a long time :)

[@hansschweikert9153]

Before the fan ran continuously, I also had idle issues and transmission skipping issues, just like what you are describing. How hard would it be to just replace it with another 10 pin connector? I'm tempted to just bypass the two wires like Ivan did, but now I'm wondering if other pins are going to fail and cause assorted malfunctions. Bad design.

[@sandyande]

thanks Ivan that was a brilliant case study, I learned a lot about electrical trouble shooting and using the ammeter, hope u charged plenty and remember there is always the cash in the fuse cover! cheers sandy

[@robertjohn1157]

Pa awwaaaay was

[@bonacjunk9983]

dude! thank you my shop was chasing this problem for a week this ended up being the problem... super helpful

[@PineHollowAutoDiagnostics]

Cool! Hopefully the methods shown here will cut down the diag time from weeks to hours on the next one 😁👌

[@imprezaaudi]

Eric O had the same connector go on one of his repairs. This time it went up in smoke and had symptoms of alternator and abs issues. It took out 2 fuses, a 7.5A and 10 Amp both wires were next to each other in the connector. Full rewire of connector cured all faults

[@lupedelacruz4152]

Love that you take us all the way Amigo. I'll keep watching sir

[@ns671fr]

Pretty awesome diagnostics, dont stop doing this

[@linfieldsclass197]

Same issue and your video was a great time saver. Excellent diagnostics process!! Mike in Canada

[@SimplyDiagnostics]

Great walk through system design and operation Ivan. Thanks for sharing.

[@firehouses5firemenfiretruc571]

Wow, nice investigation on this, very impressive detective work. Really impressed with you drilling into the schematic. Could be my problem as well.

[@whitetiger8652]

Great job Ivan. The test light is always a valuable tool.

[@jimyaekel7385]

Thank you. Just had this exact issue pop up on my 05 Highlander and jumped right on KZbin to investigate. I JSU put $2k into repairs on both my vehicles and didn’t need this. I went right to the plug you identified and could here the relay tripping and arcing when I wiggled the connector. Then it got hot and saw a puff of smoke. Pulled the battery, opened the plug and found the pin pretty much melted. I hope jumping around the connector is the solution. I’ll let you know.

[@anythinganytimealways]

Well, did it work or catch fire?

[@schrodingersboxquantummeka2008]

Wow never seen that before! Nice diagnosis! But I'm gonna go take some dramamine now

[@Mr92cadi]

1, 2, freaking barbecue! Quick and dirty repair. great job

[@8power0]

Another excellent video , that amp probe is a must have in automotive today .

[@kenbig1]

Exactly my symptoms up to and including isolating the ECM. Great video in any case I never would have got this far otherwise or understood as much about how the circuit functions. Trying to figure out how to unplug the connectors and remove the relays is not an easy task. I found when trying isolate the ECM that the plug wires on the male side of the plug were hot to the touch. And there was contamination inside male plug half around the pins. 2005 Highlander. I hope this is the answer... and cleaning the plug I found a loose pin that was corroded and easily fell over and broke...final and, I soldered in a bypass wire and now the fans, fan when they are supposed to and all the warning lights are gone.

[@jimyaekel7385]

Was it the answer? I'm about to do the same on my '05 for the exact issue.

[@kenbig1]

@@jimyaekel7385 yes it was "an" answer and did remove most of my symptoms. I don't profess to understand all I did. But simple observation of the state of the pins in the connector said those were a likely starting point. I made sure I understood and and documented the pin out and the wire colors before I started. I found some crimp splices that worked well and sealed with heat gun.

[@jimyaekel7385]

kenbig1 as an electronics technician I think you did a very methodical troubleshooting job. When my connector started getting hot and even smoking from manipulating it, that was a pretty obvious sign. But on mine the pin actually cooled off and the green/ yellow wire alongside it showed signs of overheating also. For good measure I bypassed both of those and the red one you did. I solder wires, just wish I’d had some shrink tubing. I’ll have to go back to it. But the fan running issue is eliminated and no more relays clicked and arcing. Thanks for your post!

[@rogerlang7250]

Had the same issue with my 2007. Luckily it turned out to be a relay stuck closed. Thank you for the video!!!!! I wouldn't been able to figure it out with out it

[@PineHollowAutoDiagnostics]

Good to hear Roger! Feel free to donate a few bucks via the PayPal link; it helps to fund the information services like wiring diagrams that I share in the videos 🙂 Thank you!

[@christopherlee2]

Thanks!!! This saved me so much time.

[@oszkarlazar7581]

Nice clear analysis and resolution. Impressive. Well done.

[@wtbm123]

Good find , Who would of ever thought

[@joachimbartsch1045]

this is an old video, but I just had the exact same problem 2 days ago. Helped me a bunch to find the fix. THANKS!

[@Yonipzz]

whats the issue and how you fixed it? thanks.

[@joachimbartsch1045]

@@Yonipzz The wires to the fan/switch right at the plug from the main harness were burnt. Just repaired the plug.

[@Yonipzz]

@@joachimbartsch1045 thank you for a quick response.

[@andreagili4589]

Hi Ivan, watched all of your videos and i have to say have come a long way with your diagnostic capabilities. You even convinced me i need to buy a stand alone amp clamp so i don't have to take out the scope every time. Good job with this :)

[@SteveRobReviews]

Nice, don't see that often. I've never seen it inside the connector . 👍👍

[@EXOVCDS]

Far out, far out... well done, well done!

[@jeradooka1840]

Thanks man, I have a similar issue in my Toyota Camry. Gotta use your technique

[@stevescott8758]

Great example of logical testing Ivan.

[@rogermendoza6150]

Awesome 👏 work helps me learn more about diagnostic troubleshooting

[@bruceirvine3962]

Sounds like you're fighting allergy or a cold. Stay strong!

[@calebcaruso]

This is so helpful i have an issue with corolla ae101 very similar. Will now look into connectors on the bottom of the fuse box and check on the pins.

[@samd410]

Ivan, you are great mechanic. keep up the good work

[@rabidlumberjack]

Literally just had this issue today! I followed this video to the t and my test light showed the exact same symptoms. Thank you so much for posting this so I didn't have to take it to the dealer and have them chase this gremlin.

[@PineHollowAutoDiagnostics]

Wow same exact short in that connector?! I would never have guessed that anyone would see this problem, as it was so bizarre!

[@rabidlumberjack]

When we unplugged the ECM and wiggled the connector and the test light started flickering I almost lost it haha

[@rmdaniels267]

I have the exact same issue going on with my Solara. How does one go about fixing those wires? This car is pissing me off, I mean I can't walk away from it without pulling the two fan fuses.

[@zzali1831]

Thank you that was really helpful I have this problem today. Hoping I will fix it tomorrow.

[@zacatecano1986]

Great video , good diagnosis skills ! Testlights are awesome !!!

[@billyr9840]

Ivan, very well done deducing the possible causes of the short ! Is it drawing current and how much ? Now that is what a Amp Probe is suppose to be used for! excellent diagnostic skill !

[@LegacyGarage]

Hey thanks man this was life saver. Had this happen on 1 i had after a sunroof drain clogged so i was looking inside and cleaning connectors. Found this and could hear the connector sizzle while unplugged. I ended up also having a battery light on because the wire it shorted to lost connection after i repaired the other.

[@PineHollowAutoDiagnostics]

Nice work! Crazy that a connector can short out internally like that 😅

[@LegacyGarage]

@@PineHollowAutoDiagnostics yeppers, i cleaned it and it was good but i couldn't leave it,i knew it happen again so i just bypassed it like you

[@grzegorz16100]

I would put some sort of connector on that wire in case if it needs to be unplugged. Great video.

[@windsorrocks]

The 'wiggle jiggle' test is legit. Nice video!!

[@karlbuttler]

Amazing how you chased that down...

[@MT-rp1kb]

Wow, I’m having this exact problem in an 05. Amazing work thankyou.

[@PineHollowAutoDiagnostics]

Yeah it's a weird problem lol

[@MT-rp1kb]

@@PineHollowAutoDiagnostics somehow the voltage reg got cooked when jiggling wires.,,

[@DiyMech]

Superb piece of fault finding Ivan, DC ammeters are a lot cheaper nowadays an excellent fault finding tool, pick cheap ones up for around £30, but if you can afford the top notch ones then carry on. What's the odds on a local garage finding that one then ?, keep up the excellent videos.

[@PineHollowAutoDiagnostics]

+DiyMech Thanks! Yeah the more I use the amp clamp, the more I like it...great non-intrusive tool with no leads to plug in or get in the way. In this case it was the most effective way to pinpoint the problem without cutting wires or poking holes. It's a fantastic piece of equipment when paired with a test light :)

[@redconvertible2865]

Hi, thank you so much the video, it was very informative. I have a 2008 Lexus RX400 H. Both radiator fans and heater blower fan continue to run with engine off and keg out. When turn on with they are off. I did all the tests you have shown in the video. Tested the load side and it has 12V and side the going to fan and feed 12v to side and unplugged the fan and everything is just good. The problem is control side has 12V with engine off and key out when I remove the heat fuse it off. I also check the negative side of the control side of the coil and it going fine ( in your case you 12v) I don’t have the wiring diagram for it, can you please help me find what is feed the control with key out. Thanks

[@toyotatechMDT]

Nice video! Toyota fan control is strange. Same set up on the rav-4 as well! They do have to break sometimes or I'd go hungry!

[@PineHollowAutoDiagnostics]

+Toyota Tech lol I thought you would chime in on this one!

[@zvit]

BBB no longer offers TSBs and wiring diagrams. We apologize for the inconvenience.

[@luigitorchia8866]

Another job well done. Congrats.

[@estrelladelnorte1308]

WOW! that was amazing diagnostic.

[@DeRanged218]

I’m having the same issue. I understand 99% of the video, except the end. What wire did you pull and solder together?

[@laohantun7404]

Unbelievable ......thanks Ivan....

[@qwarko3658]

Great find! I guess the owner got lucky those +12V fed into the computer did not damage it. One small thing I do not get: if that wiring diagram is correct, then once the engine is warmed up and the water temp switch closes, then it would have been a direct +12V short to ground? There must have been a blown fuse somewhere in this case?

[@PineHollowAutoDiagnostics]

+qwarko Now that is a fantastic question! After digging around more wiring diagrams, I finally tracked down that WHT/BLU wire that was shorted to the fan relay control pin at connector EB2. It is coming straight from the ALT-S fuse (7.5A) in the relay box, on its way to the alternator. Now since it was at 12V during testing, that 7.5A fuse is definitely NOT blown. From this we can conclude a few things: 1) Neither Water Temp Sw. #1 nor the A/C pressure switch tripped during the fault. 2) The ECM never commanded the fan ON at full speed...or if it did there was some current-limiting in the ECM to prevent current over 7A. I did NOT verify if that driver was still functional after the fix... 3) Under normal operation, low speed of both fans is enough to keep the operating temperature normal (Relay 3 turns on both fans via Water Temp Sw #2). Perhaps I should have verified that ECM driver was still functional...wonder if that would throw a trouble code? Thanks for the comment!

[@qwarko3658]

+motoYam82 Not sure about the trouble code... Another possibility though might be that the ECM wire is just for "sensing", not "commanding" - the ECM might be checking if the a/c pressure or engine temp is too high and then turns off the a/c clutch or otherwise limits engine performance... Just an idea. Anyway - cool diagnostics and thanks for filming it!

[@ChueyMr11]

The Toyo cooling fan circuit is a nightmare. The ECU does not control the under hood fans. They are controlled by the ac water temp switch and the ac pressure sensor. Never seen a short in a connector. I have seen open circuit connectors caused by improper backprobing. Good job! I would have given up.

[@hansschweikert9153]

Holy crap, batman! My '04 Toyota Highlander is doing this exact thing. I never imagined that this would be such an involved diagnosis. I mean, when do plugs go bad? And how many mechanics would find something like this? Thanks.

[@Agyaboat2]

Very Good job well done. You are the best

[@techsavantlove]

Perhaps the internal short was partly or mostly due to heat breaking down the insulation? (melting)

[@PineHollowAutoDiagnostics]

+douglas “The flame is dead” lee In this case there was evidence of chemical corrosion on one of those pins inside the connector. I assume battery acid caused the damage at some point since this connector lives right by the NEG terminal. I also know that Toyota batteries like to leak acid :)

[@wldmhd]

Amazing.. lot of information Thanks man ⭐️💕

[@trippplefive]

how did you bypass the wire? did you solder the one wire directly to the corresponding with on the female side of the plug?

[@eddiemartinez265]

IVAN YOU SOUND MORE LIKE UNCLE ERIC EVERYDAY.

[@trevorvanbremen4718]

You were possibly _LUCKY_ that the PCM (and the other two switches) survived this fault. If the 'short' within the connector was capable of supplying any decent amount of current, then EITHER a fuse would 'let out the smoke' when the PCM commanded the fan on, OR, the 'switch' within the PCM (probably a MOSFET) would have let out its magic smoke. It would be interesting to know where that other wire in the short (white with blue trace) went to. My guess would be that it's probably on the controlled ground side of some other (medium current) component and was only capable of supplying a limited amount of current.

[@dittybur]

awesome video awesome job thanks man

[@jassingh9083]

I have a Peugeot 308, the fan keeps running as soon as I start the car in the morning, so the engine isn't hot at all. I've replaced the thermostat sensor & the problem is still there. Could you please assist me with my problem as I feel the garage is trying to rip me off. Look forward to you're reply. Thanks Jas

[@PineHollowAutoDiagnostics]

Get a wiring diagram and see what controls the fan relay 👍

[@ralphcooper7332]

What do you mean by bypassing the two wires?

[@anythinganytimealways]

I have an 03 highlander 3.0 v-6 and the fans won't come on at all. Even when turning the ac on, nothing. Both of the fans work when given 12volts. All the fuses are good inside and out. Replaced the relays with new and that didn't work either. Temperature reads normal but its winter. Its not overheating, yet. I'm looking into replacing the fan switch but would that cause them not to come on even with the ac active?

[@SmoovMedia]

Were u get the diagram?

[@ericcorse]

Well done a real head scratcher.

[@bruceaugustine6486]

the EB2 connector is my guess second connector under thr front of the relay box. either melted of water intrution and corrosion.

[@domohedafe5994]

How can i get that wiring diagram

[@kayodeadeogun3325]

Thanks for wonderful video. My Highlander radiator fans run on low speed,but when i switch on A/C ,it runs on high speed. This has make me to change the radiator bu the fan run on low speed. What could be the problem? My Highlander is 2004 model.

[@JerodMatlock]

that was a good one! Thanks for showing us

[@Havemercyonme08]

Oh man, how long did you take? I’m going to bring my car for service 180 an hour to figure out. Hope it didn’t take as long as it did with you. My fan comes on when I turn on my high beans when I shut off my high beans, the fan shut off truck has to be off so weird

[@PineHollowAutoDiagnostics]

Figure it out yourself! 😎

[@GRowe1978]

That was cool! Awesome video Ivan!!

[@eldocilospina6091]

Ivan you are a superhero

[@nickatdallas]

How do you check relay? What if the relay was bad?

[@wldmhd]

I touched my 2008 FJ cruiser headlight plug when installing my xenon hid.. Now there is no low beam, I am preparing to do same thing you do here. FJ cruiser DRL with headlights system makes things very difficult, God help me I even bought Fluke117 for this. Do I need lights tester!

[@brolicdabrave]

Fixed my issue also. Thanks

[@philh9238]

how long did this take to find out in real time not camera time. very interesting find

[@PineHollowAutoDiagnostics]

+phil holbrook hmmm about two hours with the repair and filming...

[@ozzstars_cars]

when you did the repair you mentioned you spliced the two wires, bypassed the one wire 27:12. I am confused so my question is which wire were you speaking of according to the diagram that was bypassed and what did you splice it to? thanks

[@PineHollowAutoDiagnostics]

+Ozzstar Ended up bypassing the connector with BOTH wires that were shorted together. The pin for that white/blue wire (not on the diagram...not sure where that went) was actually very weak inside the connector due to corrosion, so had to bypass that one as well as our red/yellow PCM control wire for the fan relays :)

[@ozzstars_cars]

Okay gotcha now, you bypassed those two wires from the connector. You connected the matching wires (butt connection), outside of both connectors. Nice fix man, great diagnostics

[@hansschweikert9153]

What wire did you bypass the red/yellow on to? The left side (female) plug has no red/yellow wire coming out of it.

[@wysetech2000]

Everything I was gonna say has already been said, Ivan. But I would like to ask a question. Where the hell do you find all these obscure problems? Never had a connecter problem that I couldn't see or at least tug a corroded wire out of a connecter.

[@PineHollowAutoDiagnostics]

+wysetech2000 Hah this was a rare case where I got to look at the car before it was thoroughly "molested" by parts changers :) Would hate to think of the worst-case scenario where you have to dig through the built-in problems before getting to the original issue...Remember the Acura?

[@wysetech2000]

+motoYam82 Yeah, it's always good to be the first one to work on a problem and yes I do remember the Acura. Whoever worked on that mess shouldn't be allowed to open a hood. {:-) It's this kind of work that keeps making you better and better as well as successful in your business..

[@thedreadedgman]

+motoYam82 to be fair the relay had already been changed ;)

[@JD-iu3vi]

Ivan, I got 2005 Highlander with a intermittent P0012 code and the VVT solenoid checks good but I want to check the filter. I can't figure out where it is located. Does anyone know where it is located?

[@markferraro5250]

excellent video ivan thanks

[@nandog6946]

Great diag on this.

[@CravinMorehead420]

Good old test light and ammeter. Feels good solving problems like that..

[@wyattoneable]

Wow, nice find.

[@paulmoffat9306]

Most likely, there is a stray wire from the terminal crimps that was bridging between the 2 positions - one of the stranded wires was not captured in the terminal.

[@amdemik]

Educational as always

[@rrmech11]

Good job Ivan