How to test an electronic thermostat (GM design) part 1

[@adrianfrias4019]

Dan I heard you say that some viewers commented that your videos are too long. I want to affirm you on how informative your videos are. Appreciate you thought process and even your mistakes. If you made quick "pop tart" videos I would probably not view your videos. Please continue your hard work. Negative comments can be very discouraging and hinder progress. Just remember, it is a sign of trouble when everyone agrees with you. There would be no motivation to grow. Again thank you for your diligence to detail.

[@dynotec1]

Danner, I have just discovered your channel and your approach to diagnostics and I have to say I'm completely blown away. I don't know if it's just me or what, but the way that you explain things and how you go about them is perfectly clear to me. I have been in the automotive repair industry for twenty years and I've sat in plenty of classes with some great instructors and you are at the top of your game. I'm in the process of watching all of your videos and I'm picking up great stuff in all of them. Thank you for sharing your craft! Bart

[@rodx5571]

Many thanks for your videos. watching your vids has made me a better diagnostician. i have 4 local shops that bring me stuff they cant figure out, and i always succeed where they fail. Your basic methodology and grasp of theory and operation based on circuit design (which i have learned as i see the advantage) makes diagnostics simpler. You turned me into a "scope guy". I am a better technician as a result. I still have to get my hands dirty turning wrenches, however i do get most of the electrical diag work, which suits me fine, and i make money on diag where many don't. Again thanks. keep em coming.

[@ScannerDanner]

awesome brother! May God continue to bless your mind and hands. thanks so much for your comment.

[@gromit1000000]

This is a common setup on a lot Europe cars Bmw vw Audi Vauxhall all use some type of stat that does the same thing. It's to help the engine stay at a better temp so fuelling can be controlled better. An old type wax stat can have a 20 deg swing up or down so fuelling could be off a new type stat has poss only a 5 deg swing so engine runs at a more stable temp making fuelling more accurate.

[@zochpeter]

all it is just to lower emissions, not fueling. everything is to make Brussels happy

[@EricChee]

Recently my gfs car, opel astra j, which has same setup like you diagnose on tje video, got same problem. When dealer service adviser explain without proper explanation, i could not understand but now you explain everything. Thank you so much.

[@Bushougoma]

The component on the thermostat is called a bias heater. The biased thermostat must be for tighter emission control. A critical variable in emissions is engine temperature. How much of an improvement they're getting in emissions over a regulator thermostat I'd like to see. Or maybe they're just using it to get the engine warmed up and into closed loop quicker. A cold and warm engines emissions are night and day. Your guess is as good as mine. In any case this allows the PCM to accurately regulate the coolant temperature using the coolant temperature sensor as feedback. Gas clothes driers use a similar principle to avoid the cost of using 3 different bimetallic temperature switches for the different selectable temperatures (low, medium, and high). There is one temperature switch and a resistive heater is put into close contact with it. By placing a different resistor in series with the heater for each temperature setting the bias heaters temperature is controlled. By preheating the bimetallic switch it will open at a different temperature than it's rated for. The design on this vehicle is a slight variation using pulse width modulation to more accurately control the heater instead of a resistor. I've never seen one either but as soon as you said the word heater I knew what it did.

[@ScannerDannerPremium]

Nice! Thanks bro

[@LynxStarAuto]

Wow that is an excellent circuit description. Manufacturers are getting better with these flow charts.

[@chrisbartman5125]

Yes, fundamentals is key. I'm still waiting for the computer controlled "paint color" options. I do have some industrial equipment where the computer adjusts "actuator pressure" based on amount of current flow in the actuator circuit. I thought that was a rather cool concept. Fine instructional work Mr. Danner.

[@jptrustno1]

Gah dang, scannerdanner is an expert at what he does and teaches. I wish i knew half the stuff this guy does, especially with the snapon scanners. Great job!

[@ScannerDanner]

keep watching, I can teach you! Join my premium channel if you want even more www.scannerdanner.com

[@TheWaelabo02]

Hi. BMW use same setup for years and always change thermostat for Same reason Thank you for your good job.

[@nicknicu1787]

Thank you Paul! Great video as always! It's amazing the lengths car manufacturers go in the name of emissions. What was wrong with the plain old mechanical thermostat…?! You put an electrical circuit in there and guess what…?! That's the one that fails!

[@craigstites8839]

mechanical t stats failed all the time. stick open and there could be a code for coolant temp not reaching operating temp. stick close and severe engine damage can occur

[@pospc2]

Thanks. I been trying to get an understanding on this thermostat heater deal. Its a relatively new thing to me.

[@EzRepairs]

Hi scannerdaner, i work for a rental company and during the 2012/2013 chevy cruze wee had a lot of cars with this DTC, I always wondering what was the function and cause for this code as wee never got to work on this problem because the cars were steal under waranty, thanks for the video. Best teacher ever...

[@techsavantlove]

Paul, Here is another submission for the Suggestion Box. Perhaps you have addressed this in other video's, or on the Premium Channel, but I have not seen it myself. I apologize if you have already covered it. I am currently chasing a possible Key Off Drain on my 1999 Sebring JXi. I understand the principles of monitoring amperage, pulling fuses etc. However, yesterday I just came across information explaining that some Modules can Stay Awake, and don't "Go to Sleep" for some period of time. I'm not referring to my car, just all cars in general. I am not able to find any information about the subject as it might apply to my car, including searching the FSM. SO, I am a little lost for information, so I am going to have to simply wait for some period of time (I'll probably aim for a half hour) before taking ABSOLUTE current flow measurements. I also want to avoid powering down the PCM, BCM, or TCM if I don't absolutely have to. SO, the idea for you is to perhaps do a video sometime and talk about how various Modules can sometimes stay awake, and the importance of knowing this before doing current flow testing (in series with battery) in analyzing current drains. If you have any knowledge about how long various types of modules (computers) might stay awake by type or by manufacturer, that would be a bonus. I know you are not an Electrical or Short Circuit Testing focused class, but knowing the fact that the PCM, TCM, BCM, etc can stay awake for a while sucking some degree of juice might be valuable to your viewers. Keep up the Great Work as always. Sincerely.....

[@cojns1627]

+douglas “The flame is dead” lee Sorry for dragging up a really old comment, but you are correct some modules and things in a car never "Go to Sleep" with no key. What you want to look for to understand this is "Parasitic Load Testing" A parasitic load or Draw is anything that draws current when the car is off. Some of them shut off a couple minutes after cutting the car off, like the module that keep the lights on at night so you can make it to the door. A shorted wire will be a permanent draw. Off hand, I can think several normal current draws with the vehicle off: Radio memory, storing clock and station data, Alarm system monitoring, ECM modules memory storing trouble codes (That's why disconnecting the battery clears them). Some drains are vehicle specific. Some are added by users by wiring things like amps up incorrectly or leaving splices bare. So, I guess you can see how difficult it is to find a battery drain. Sometimes you have to disconnect parts of the harness to narrow down what parts to look for. Then disconnect components until you find it. Look on the wiring diagram for "Hot at all times" and you'll also get an idea of where to start looking. But, if anybody has replaced the factory stereo I'd start looking there. 9 times out of 10 it's a bad wiring job with lots of electrical tape and that's where it is. Then again, check behind the radio anyway, sometimes they stick the factory radio back in to resale the car. Hope this may help someone.

[@turb099]

Love you no hommo. U are so much help Just had 14 cruize with this nightmare thank you

[@ScannerDanner]

lol love you too

[@EminHVAC]

Outstanding work Danner. I stumbled on to you're channel by accident lol. I absolutely enjoy you're diagnostic skills. Thank you for the videos bud. Subd

[@ScannerDannerPremium]

Thanks so much!

[@searcher6855]

Great vid Paul. Many thanks again as always. I actually broke one of these a couple of weeks ago on a 2010 Chevy Aveo while doing a cooling system flush. The thermostat looked removable from the housing, but as soon as I twisted it free I realized that the wires had broken. I had to eat the cost, of course, but I've been racking my brain trying to figure out how to do a flush without pulling the thermostat since it's all integral to its housing & electric heater. After watching your video I now know what I should have done, and am posting here not only to say thanks for another great video but also to share what I came up with. Since this is a pulse width modulated part, grounding the control side should force the thermostat to open, thereby enabling a good flush. I'll use a 'soft' ground of course by using my test light and this'll be my standard procedure in the future. Does this sound right to you?

[@ScannerDannerPremium]

Sounds like a good idea but we need to be careful about overheating the element inside the thermostat. It could be that is why the manufacturer limits the amount of bidirectional time I can control this thing. Just tread carefully.

[@philh9238]

the way the trouble tree is gm has you use a test light connected to the connector unhooked in both terminals of the connector command the thermostat on watrch and see if it turns on and off, if it does ohm out coil in thermostat. but your way is nicer keep up the good work

[@ScannerDannerPremium]

That is actually a great test and I'll mention it in part 2. Thanks!

[@philh9238]

i guess you could say im aftermarket to i work at a car rental place as a mechanic. can you answer me this i was working on a crank no start on a 2014 fiesta originally came in with diesel in the tank. i siphoned it out. checked injector pulse,fuel pressure, spark. no start finally i said what if i do compression and i checked it it was over 200 in each cyliner. had a broken timing belt with 14,000 miles. how would a broken timing belt cause way higher compression?? i have no idea

[@franciscofurlan4001]

If I don't have instrumental, can I try with an eléctrical bulb to know the pcm si working?

[@OtomobilSevdasi]

I want to install 90 degree thermostat software for my Chevrolet Cruze 1.6 gasoline car. There is no one in Turkey who understands this. My car is running at very high temperatures. I need your information, dear group members. It is necessary to update the thermostat from the brain so that it turns on at 90 degrees. If anyone knows how to do it, can you help?

[@autoparts3217]

HI DAN, I know not exactly related but, what would cause my brothers 2nd Gen Dodge Dakota v6 Pickup to get p0300 random misfire DTC? He has given the igntion a full tune up replaced plugs, wires and cap/rotor. He thinks maybe the distributor drive hear or shaft has wobble or too much play in it. But that is just a guess. What is most likely cause from your experience and how should he check it? Thanks

[@ScannerDanner]

from experience? nothing on that model. From standard practices, you need to check injector flow and run a compression test next Here is a video on injector flow testing kzbin.info/www/bejne/iaS8fpxprtFjipY My first video, so very poor camera work, but good quality

[@autoparts3217]

Thanks

[@teamjin]

hello. good video.. however 800ma can fully open thermostat?

[@philh9238]

i just did one of these 3 days ago on a 2014! your way was alot better. what is your favorite brand of car to work on?

[@ScannerDannerPremium]

Any that give us aftermarket guys as much bidirectional control as possible :)

[@happy543210]

two year old car...shouldn't this repair be covered by the warranty?

[@SEXYTECH1000]

THANK YOU PAUL, GREAT VIDEO!!!

[@littlebeargaming8267]

Great video as usual.

[@paulpickering.]

Hi SD I have just recently discovered your videos and loving them, I Am learning plenty. You keep mentioning your book but what is it called, and where can I get it in the Uk. Thanks

[@ScannerDanner]

Thank you! It is only available through my website and we can ship anywhere in the world. Shipping to the UK using USPS is less than $25 I have an eBook also that sells for $50 and give you immediate access, but you cannot print from it.

[@TTRVision]

there are cars with fully electronic thermostat control? (direct drive valve on stepper electric motor). I assume that this could rise the cost of the unit but it will work and react very fast in maintaining the coolant temp....

[@ScannerDanner]

You're asking me or telling me? I am unaware of a fully electronic design. Thank you!

[@TTRVision]

I`m asking :) That design I described it`s my it's my idea of an fully electronic design. that design will have no delay in the valve movement / temp control. thanks again for all the videos and best regards from Romania ;)

[@zochpeter]

@@TTRVision actually, the "delay" is a good thing. it has to do with thermodynamics. having a thermostat to react too fast will cause thermal shocks and also hot water flowing too fast in the circuit is not able to give away its thermal energy.

[@Mikesky10]

thanks to this video now i know how to operates this thermostat, but there is two things that i just dont get it; first is how putting a heater inside the thermostat will make the engine work hotter?; and two, why does the engine on high loads conditions needs to be cooler?, if we know that with an engine hot there is lower emissions?

[@ScannerDanner]

read through some of the comments brother. we addressed this and I forget all of the details

[@alertjean]

Is there a resistance measurement we can do on the terminals of thermostat to infer if it is open?

[@ScannerDanner]

possibly but without looking at service info. I am not sure. Here is a DIY version of the service info I use. It may help you eautorepair.adtrk.biz/?a=10817&c=24&p=r&s1=

[@mototechno834]

Hi Paul...how can we determine if the device is PWM or not????

[@ScannerDanner]

It really helps to know exactly what the device in question does. Is it just an on or off type circuit, or do we need every range in between on and off. Hope that makes sense

[@farukhnawaz4071]

Hej Paul. My question is are electronic thermostat is open also with coolant temperature? If wiring is bad or not working give answer thanks

[@ScannerDanner]

yes, coolant is involved too. I forget the purpose behind it, I think we talked about it in this video

[@farukhnawaz4071]

ScannerDanner Thanks alot my English is not very good.I thank you for the answer

[@olipirard]

Does those fault numbers have the same meaning what ever the make of the car is?

[@chrisbartman5125]

Someone may correct me if I'm wrong - I believe all "P zero" codes are [Powertrain] OBDII compliant (regardless of manufacture), where "P one" codes are manufacturer specific.

[@ScannerDanner]

Exactly

[@99rattle]

Danner been busy wid his money making channel...lol..& us cheap skates have to wait for some more vids. :) This stupid thermostat heater bs on a good percentage of 2006 on vehicles in UK , cus EU I suspect. Some even more complicated how they operate, on VAG vehicles they use rpm & temp open the stat,, what the hell was wrong with simple thermostat,. sigh

[@ScannerDannerPremium]

I know right? Shame on me :)

[@michaelovitch]

Do you know why they want to heat up a thermostat ? I don't get it. as i understand opening the coolant cicuit to cool down the engine will not help to go in closed loop to pollute less. the only thing i could see is to slow down the warm up phase to control "better" the combustion. Would it be used most of the time in traffic jam when the mechanical thermostat cycle a lot and the temp fluctuate a lot ? what am i missing ? If it's the case why do those guys don't use a thermostat in the block the temp would fluctuate to around 3 degrees C° only.

[@zochpeter]

it is more complex than that. it uses RPM+calculated engine load(temperature to air mass)+temperature difference compared to water temp at radiator outlet+ heater knob settings on non climate controlled vehicles, vehicle speed etc, you name it.. on VAG devices, there are at least 3 different MAPs that control the heater circuit. + it controls the radiator fan :D if somebody can thing of any overengineered item in today's cars, thermostat is clearly the winner :D www.volkspage.net/technik/ssp/ssp/SSP_222.pdf

[@zochpeter]

@@michaelovitch in traffic jam, they use it in that way, that they open the thermostat at higher temps compared to regular. lets say regular thermostat opens at 87-90 degree C, this one in traffic jam, engine idling, vehicle speed 0, engine load minimal, it will open at 105-110 degree C to lower emissions.... (fyi the "old mechanical" setpoint is 110 degree C as a failsafe) that is why they need to heat it, otherwise it would be shut closed until water hits 110. meaning, they just heat it too 110 with ECM to open)

[@michaelovitch]

@@zochpeter To resume,it's to run leaner,emission is a secondary concern. Like i said 3 years ago,a thermosat in the block,and not in the head would be way more efficient at heat regulation,while being way more reliable than all that.

[@jivandwarka5475]

OK, so this shop calls in Danner for a simple thermostat !? Don't waste his time !

[@ScannerDannerPremium]

This was a students car at the school I teach at (Rosedale Tech)