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2005 Grand Prix - temp gauge/cooling fan issues.



ahhhh, well this might make sense now because i have been keeping my car plugged in quite a bit lately.(it's been insanely cold...at least -30 overnight). Dadio, i'm also from winterpeg.

Synthetic, i changed my thermostat and and coolant temp sensor and the problem persisted. Guess i have to go get the code cleared.
 
Well Im sorry to hear that, but I'll have to tuck away that information about the block heater because I had never heard of that before.
 
I've never heard of that either. I guess that's why my cars block heater was designed for a temp below -18. The plug end has a sensor in it to control this. I had cut mine off and put a normal plug end on so i can keep the block heater going whenever i wanted it on. Woops!

Synthetic, your advice did make sense and thanks for the help regardless. Hmm...since it is xmas eve tomorrow, perhaps the GM dealer will be nice and not charge me up the ass to clear this code.

Needless to say, i don't think i'll be plugging my car in much anymore.
 


The cord is quite expensive. I had the same idea but the dealer stopped me from cutting the cord. This is how the dealer explained it to me.
The block heater cord has a thermistor (thermostat) built in and only allows the block heater to work at temperatures colder than -18 C (0 deg F). The computer does a check of three sensors, coolant temp, intake air and (sorry I can't remember the third) before the vehicle starts. If the computer finds one of the sensor readings is out by a large amount it assumes that sensor has failed and sets the code. The computer is programed to ignore the sensor temps below -18 deg C on start-up.
The problem occurs if the outside temperature warms up while the vehicle is plugged in and you try to start the vehicle.
If the temperature warms up from say -25 deg C to -18 deg C while the vehicle is plugged in, the block heater cord cuts the power to the block heater. (this is normal) If you now try to start the vehicle the coolant temperature is still warm. When the computer does it's test, the coolant temp sensor indicates a higher reading than the other sensors and assumes the coolant sensor is faulty and sets the code.

Hope this helps and your problem is fixed by just resetting the code.

I hear Mexico is warmer than this country. -30 this morning in Winterpeg and yesterday was +30 in Mexico.
 
I had the code cleared at Park Pontiac this morning at no charge. I was quite surprised at that. I've had two '05 grand prix's. The one i bought new obviously had the special cord but the used one i bought this year was cut off by a previous owner. Guess i won't be plugging my car in much and i'll have to pay more attention to the temp outside. The funny thing is the day the problem started, the temp was below -18...i think in the area of -20 to -25. Weird.

Boy, i wish i was in Mexico. :/
 
I'm not sure how exact the thermistor is at measuring temperature. It could be + or - a deg or so. Did the code reset fix your problems and did Park Pontiac know about the code issue?
 
Yea the problem is fixed now. I actually printed your first reply and showed it to the service advisor when i was there. He didn't really say much. They were so busy there i was lucky enough to have someone look at it this morning. Actually, i was told to come back on monday or tuesday buuuut since i had shut my car off when i parked inside i was unable to start my car again. That's when he told me he would get me in right away and have the code cleared.

I guess i won't plug the car in unless it's closer to -30 out. When are you plugging your car in now? You said you had that problem twice even though you have the proper cord, correct?
 
Well that is awesome that you got it all taken care of. Im also glad to know this information too. I wonder if this is true of all GP's with a block heater or just the 04+. This is the first I have heard of this issue so Im suspecting the 04+, but I could be wrong.
 


Yea i think it's only the 04+ models that have the special cord but i could be wrong. Synthetic, thanks again for your help. What a bizarre problem though hey? Was the special cord really necessary? I mean sure you might save a few bucks on electricity but come on GM! This is the only problem i've ever had with both my 05's, and what a stupid one at that! Oh well, maybe i shouldn't ***** about such a silly problem considering it's not a huge issue compared to some other peoples problems.
 
I wait until -23 at least, and I make sure the temperature is not rising overnight and yes I do have the proper cord. I take my car to Vickar on the other side of Regent.(not a plug. This is the first shop I visited)

SyntheticShield,
I think you are correct. The problem is from 04+ models of Grand Prix and I'm not sure about other GM vehicles as some of them have the same issue. I emailed GM a week ago and they are looking into this.
I think this is a great forum with lots of info and intend to spend some time reading the posts.

Happy Holidays
 
Well I tell ya, I really really like to sharpen my troubleshooting skills in relation to doing so without being in front of the car with any tools or test equipment but part of that process is putting your neck out there and saying I think this is what it is based on the available information and then accepting that when you're wrong, you're wrong and in this case I was big time. But, that said, I learned something and that makes it ALL worthwhile.

I'll take a ding on whatever reputation I have here anytime that I learn something and am able to improve down the line.
 
Well i've read some of your other posts and you seem quite knowledgeable. Of course sometimes you can only speculate when it's not possible to be in front of the vehicle in question.

Actually, i was just reading the Dexcool thread you had posted in. I'm almost convinced to go get that taken care of sooner than later. Lots of interesting info in this forum and i think i'll be doing quite a bit of reading in the weeks to come.

Anyways, have a good xmas guys and a happy new year.
 
Well, with regards to Dex-Cool, I'll put it to you like this. Had I been running for president, my platform would have been a ban on the stuff if that tells you anything about how much I care for it.

Merry Christmas to you as well.
 


dadio said:
hello
i'm new to this forum. I've been searching the net for problems like this and may have an answer to your problem.
I own a 2007 grand prix and live in winterpeg. I have had the same problem 2x now. If you plugged the block heater in and the temperature was warmer than -20 deg c when you started the car, a code has been set in your computer. This code disables your temp gauge and runs your fans all the time. It also runs the engine rich thinking the engine is cold. When you try to restart after the engine is warm it floods itself.

When the code is reset the engine and guage return to normal.

The problem is not just with the grand prix but includes other gm cars and trucks.
Today i was about the 12th person to have this fixed at my dealership.
My car is under warranty so the fix is free. This problem is known to gm and requires a fix(hopefully soon)
a dealer should be able to clear your code in a few minutes while you wait.
Click to expand...

i live in winterpeg as well....I own a 05 grand prix, the dealer told me the temp sensor wasn't the problem...the thermostat wasn't the problem...however the temp gauge was not working, so they replaced the entire gauge cluster to the tune of $700+!!!!! Before any of these problems started I had just replaced the plug end to my block heater because it was stripped...the dealer wasn't able to figure whats wrong...and this has happened now 2 times since they replaced they very expensive and unneeded gauge cluster!!!!!!!!!! now i'm pissed.
 
Here is an email I sent to GM:
There is a problem with this system. The short answer is that the computer on the vehicle is seeing the coolant temperature sensor too warm when the rest of the engine is cold. There is also a problem with different vehicles of the same year including some of the diesel trucks. This information can be found all over the internet and also has been recorded at the dealerships. Code DTC P0116 Perhaps GM will determine that there is a problem and issue a service bulletin to reprogram the computer to ignore the coolant sensor during cold starts. Chevy Equinox 2006. Plug in block heater and it kicks out codes. Engine is hard to start and temp gauge stops working. (Heating / Cooling Heater Chevrolet Equinox Electrical Gauges) Please contact my service dealer for more information. Vickar Community Chevrolet in Winnipeg (204)6618391

And the response:
Thank you for your email.

In response to your inquiry, we advise that our Technical Assistance Centre advises that they are aware of this concern. However at this time there is no programming available to correct this problem.

We suggest you check periodically with your dealership Service Manager who will be the first advised of any updates in this regard.

Thank you for your inquiry, and for contacting General Motors of Canada Limited. Please visit our website again!

If you replaced the plug end you may have cut off the thermistor.(A round bump in the cord near the male 120V plug) There is very little cable from the plug to the thermistor. If the thermistor is missing you will require a new cable.$$$
Vickar clears the codes while you wait.
 
Dadio said:
If you replaced the plug end you may have cut off the thermistor.(A round bump in the cord near the male 120V plug) There is very little cable from the plug to the thermistor. If the thermistor is missing you will require a new cable.$$$
Click to expand...

So an easy fix to their blatant disregard for engineering issues is, "If the thermistor is missing YOU will require a new cable." They are not willing to replace the cable with thermistor free of charge to those who are having this issue because of their design flaw?

How can I install the cable myself instead of paying labour fees? Is it possible?
 
Last edited:
Not sure about replacement. A normal block heater cord will just plug in.
Looking at my 2007 the cable routes on the drivers side and should just plug into the block where the block heater is. Not sure if GM has a different system.
I know Vickar Chev said the cable alone was expensive.
Good luck and post what you find.
 
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