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My 2017 Acadia just started showing the steering assist warning when starting the car. Engine fans keep running on high and a/c stopped. After reading all the threads on this type of problem, a few posts mentioned cleaning the negative battery terminal. I figured worth a try. My terminal was clean, but by removing the battery connector and reattaching it, all the problems went away. Maybe it just reset a sensor? I’ll report back if the problem comes back.
 

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2017 Acadia Denali, 2004 Mercedes S-500, 1994 Corvette Convertible
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I have the same problem on a '17...same symptoms. The A/C would not engage the clutch so I took it in to my dealer. Truck has 44K miles so is well within powertrain warranty limits. The Service Manager ran the codes and found "Bad Coolant Temp Sensor on Thermostat Housing" or possible bad thermostat housing. SM then informed me that these components are not covered under the Powertrain Warranty. I showed him in the Warranty Booklet where it was covered under the Federal Emissions 70,000 mile warranty, called GM Customer Service, got a confirmation and a case number. So now it IS being covered under warranty. Dealer is replacing the entire Thermostat Housing and sensor which according to him requires R & R of the Intake Manifold and Fuel injection Rails. Problem now is that they can't find the part anywhere in North America in the parts system or at another dealer. Funny thing...I went on line and found 10: of them in 10 seconds for about $45 next day delivery. Dealer says they can't get the part before Friday and gave us a new Buick Envision for a loaner.

Apparently what happens when the temp sensor on the T-Stat housing goes bad it sends a signal to the ECM that the engine is overheating, causes the temp gauge to peg to "C", shuts down A/C Compressor Clutch engagement to not exacerbate the Overheat condition and super speeds the cooling fans. Of course it's a false flag warning and the engine isn't actually running hot. At the same time a signal to the ECM also tells the Power Steering Rack that it's Super Cold out and the lube in the steering system may freeze up causing loss of steering assist.

I know I'm not the only one that feels this way but we are all at the mercy of the lack of quality of all of these **** sensors and the vehicles built over the past 25 years becoming more and more dependent upon them working properly. Back in October, right after we passed the 36K mile "Trip Wire", we lost the "Body Control Module" which shuts everything down. I shelled out close to a Grand on that one even though the warranty book says the "Vehicle Control Module" is covered by the powertrain warranty. Turns out that the "Body Control Module and "Vehicle Control Module" are two different modules. I asked the service/parts people at the dealer to show me one of each so I could see the difference...of course they didn't have a "Vehicle Control Module" in stock to show me.I lost that battle.

This seems to be a "Cross Platform" issue with all of the GM Cars and Trucks and from what I hear from owners of other brands,this is not something that is unique to GM.

My wife has a good Idea...she says "Sell the Acadia, through some extra money in from savings and by an old GTO, 442, or SS Chevelle from the 60s and say goodbye to the sensors. The Acadia is her car and she doesn't drive it muich...the 60s muscle car idea is starting to look better and better !!(y):cool:
 

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2017 Acadia Denali, 2004 Mercedes S-500, 1994 Corvette Convertible
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OK...just got the Acadia back from the dealer. Problem solved. The R & Rd the T-Stat Housing, T-Stat & Sensor. They also flushed and re filled the cooling system. I caught a break and it was all performed via the powertrain warranty. All is back to normal. Good GMC Dealer in Ocala, Florida. BTW...the Fault Code was P0128.
 

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OK...just got the Acadia back from the dealer. Problem solved. The R & Rd the T-Stat Housing, T-Stat & Sensor. They also flushed and re filled the cooling system. I caught a break and it was all performed via the powertrain warranty. All is back to normal. Good GMC Dealer in Ocala, Florida. BTW...the Fault Code was P0128.
So the BCM did not need to be replaced? Seems odd if it did.

Or if it did. . . what has that got to do with the T-stat and sensor problem?
 

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My 2017 Acadia just started showing the steering assist warning when starting the car. Engine fans keep running on high and a/c stopped. After reading all the threads on this type of problem, a few posts mentioned cleaning the negative battery terminal. I figured worth a try. My terminal was clean, but by removing the battery connector and reattaching it, all the problems went away. Maybe it just reset a sensor? I’ll report back if the problem comes back.
I have same problem, also when it happens the temp Guage quits as well. First time, I ended up with a code saying low temperature warning/open thermostat. Happens ever so often, I do the same thing, pull off negative cable and it's good to go for a while again.
 

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I have the same problem on a '17...same symptoms. The A/C would not engage the clutch so I took it in to my dealer. Truck has 44K miles so is well within powertrain warranty limits. The Service Manager ran the codes and found "Bad Coolant Temp Sensor on Thermostat Housing" or possible bad thermostat housing. SM then informed me that these components are not covered under the Powertrain Warranty. I showed him in the Warranty Booklet where it was covered under the Federal Emissions 70,000 mile warranty, called GM Customer Service, got a confirmation and a case number. So now it IS being covered under warranty. Dealer is replacing the entire Thermostat Housing and sensor which according to him requires R & R of the Intake Manifold and Fuel injection Rails. Problem now is that they can't find the part anywhere in North America in the parts system or at another dealer. Funny thing...I went on line and found 10: of them in 10 seconds for about $45 next day delivery. Dealer says they can't get the part before Friday and gave us a new Buick Envision for a loaner.

Apparently what happens when the temp sensor on the T-Stat housing goes bad it sends a signal to the ECM that the engine is overheating, causes the temp gauge to peg to "C", shuts down A/C Compressor Clutch engagement to not exacerbate the Overheat condition and super speeds the cooling fans. Of course it's a false flag warning and the engine isn't actually running hot. At the same time a signal to the ECM also tells the Power Steering Rack that it's Super Cold out and the lube in the steering system may freeze up causing loss of steering assist.

I know I'm not the only one that feels this way but we are all at the mercy of the lack of quality of all of these **** sensors and the vehicles built over the past 25 years becoming more and more dependent upon them working properly. Back in October, right after we passed the 36K mile "Trip Wire", we lost the "Body Control Module" which shuts everything down. I shelled out close to a Grand on that one even though the warranty book says the "Vehicle Control Module" is covered by the powertrain warranty. Turns out that the "Body Control Module and "Vehicle Control Module" are two different modules. I asked the service/parts people at the dealer to show me one of each so I could see the difference...of course they didn't have a "Vehicle Control Module" in stock to show me.I lost that battle.

This seems to be a "Cross Platform" issue with all of the GM Cars and Trucks and from what I hear from owners of other brands,this is not something that is unique to GM.

My wife has a good Idea...she says "Sell the Acadia, through some extra money in from savings and by an old GTO, 442, or SS Chevelle from the 60s and say goodbye to the sensors. The Acadia is her car and she doesn't drive it muich...the 60s muscle car idea is starting to look better and better !!(y):cool:
I know this is several months old, but my 2018 Acadia is doing the same thing. It will show temperature on the dash for a while then go all the way to cold. After work, it would stay on cold, then about half way home, noticed the temperature was reading on the dash and then my AC would work again. I just replaced the temperature sensor but not the T-stat and housing because I could not find one locally. Since it was apart and I would need the vehicle right away, I just did the sensor knowing that I may have to go back in.

After replacing the sensor, it showed temperature and I let it idle for a long time and even ran a quick errand; temps all good. Next day, I am going to work and just like before, about half way there (30 min drive), temperature is all the way at cold and I get the message for steering assist reduced.

I did find TSB #17-NA-390 that references these symptoms, and the fix is to verify good connection for the temperature sensor or to update the ECM with the latest calibration.

I will have to try and find information about the power train warranty covering this problem like you did. Then I can pass it off to the dealer. Ha Ha! If not, I will probably go back in and replace the thermostat and housing. Then it will probably be to the dealer after that.

Sorry, this is a bit long, but I appreciate you posting what you did.
 

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I know this is several months old, but my 2018 Acadia is doing the same thing. It will show temperature on the dash for a while then go all the way to cold. After work, it would stay on cold, then about half way home, noticed the temperature was reading on the dash and then my AC would work again. I just replaced the temperature sensor but not the T-stat and housing because I could not find one locally. Since it was apart and I would need the vehicle right away, I just did the sensor knowing that I may have to go back in.

After replacing the sensor, it showed temperature and I let it idle for a long time and even ran a quick errand; temps all good. Next day, I am going to work and just like before, about half way there (30 min drive), temperature is all the way at cold and I get the message for steering assist reduced.

I did find TSB #17-NA-390 that references these symptoms, and the fix is to verify good connection for the temperature sensor or to update the ECM with the latest calibration.

I will have to try and find information about the power train warranty covering this problem like you did. Then I can pass it off to the dealer. Ha Ha! If not, I will probably go back in and replace the thermostat and housing. Then it will probably be to the dealer after that.

Sorry, this is a bit long, but I appreciate you posting what you did.

Any luck resolving this?
 

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I have the SAME symptoms with my 2017 Acadia the power assist warning, then temperature gauge goes to C, then air conditioner does not work and fans blow. Sometimes this happens simultaneously with my coolant draining down to empty. I disconnect my battery and reconnect it and everything is fixed.
I am out of warranty and thinking about what to do. Replace water pump and thermostat?
 

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I have the SAME symptoms with my 2017 Acadia the power assist warning, then temperature gauge goes to C, then air conditioner does not work and fans blow. Sometimes this happens simultaneously with my coolant draining down to empty. I disconnect my battery and reconnect it and everything is fixed.
I am out of warranty and thinking about what to do. Replace water pump and thermostat?
Is you Acadia the "Limited" larger size Acadia or the newer shorter +2017 C1xx version?
That seems like the way to go. But a temperature sensor might also be a problem. But about as difficult to get at as the thermostat if I recall if you have the newer LGX 3.6L engine.
So if you do all the other items add in the coolant temperature sensor or ECT as it is called.
If you have an Acadia Limited, that ECT is easier to get at.
 

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Is you Acadia the "Limited" larger size Acadia or the newer shorter +2017 C1xx version?
No such warning exists in the Acadia Limited message system.
 

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Does anyone think that it might be the battery terminal or cable?

I keep taking the negative off and it seems to work for about a day but comes right back on. I'm heading back home (16 hours) on Friday and I'd rather not have to deal with this on the way
 

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Does anyone think that it might be the battery terminal or cable?

I keep taking the negative off and it seems to work for about a day but comes right back on. I'm heading back home (16 hours) on Friday and I'd rather not have to deal with this on the way
What vehicle? How old is the battery? A failing (but not totally bad) battery could cause any number of symptoms. Might be a good idea to have it load tested to eliminate that as a cause.
 

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Does anyone think that it might be the battery terminal or cable?

I keep taking the negative off and it seems to work for about a day but comes right back on. I'm heading back home (16 hours) on Friday and I'd rather not have to deal with this on the way
My 2017 acadia was doing this every few days. I just kept taking the negative terminal off and re installing it. I ended up squeezing the lower part of the neg terminal alittle tighter so it would fit more snug on the battery post when i tightened it down. I also checked the plug on the temp sensor going to the thermostat housing to make sure it was plugged on good. Than i moved the harness around in a different spot going to that sensor just incase it was causing an intermittent signal. Between those two things i haven't had a problem for atleast a month and a half. I've even taking it on two long trips across the state of kansas with no problems. So far so good. Im mostly leaning towards the intermittent harness being the culprit. Good luck. Time will tell.
 
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