I have 2009 HHR that has had trouble with "ESC service". All thing indicated a problem with the ECM. I pick up another one at the local u-pick-it yard. I installed it and then the car wouldn't start, no cranking. I'm guessing it has to do with the VAT's system. I recall similar symptoms when I got a replacement key, I had to "learn" the key code. Is this all I need to do with the new ECM to get it to work?

 

What led you to believe it was the ECM causing the faulty ESC? It's a pretty basic circuit, generally its a hub sensor or wiring issue. The ESC is part of the ABS module, which ties into the ECM but I doubt thats the issue.

Learning the key code would be a BCM/Security function I believe. I would suspect your used ECM isn't jiving because of the VIN. It will need to be flashed either with HP Tuners or at a dealer. I would toss in your original ECM and see if the ESC is inoperable due to wiring or a faulty hub sensor. Changing the VIN shouldn't be too costly, somewhere between $150-200 but you'll need a tow. I would call your local dealer and ask if they will perform a reflash on a used ECM, they might, they might not.

Me personally, I would give your ECM another go. Unless you know for a fact, it's the cause.

 

You can get a used ECM programmed to your VIN on eBay for around $105. I can vouch for them.

ESC errors usually come from a bad hub. I don't know what would point to the ECM.

A common installation error is bending pins in the connector.

 

It all started with an ABS code (along with ESC code and traction control code) for right rear ABS sensor. I replaced the hub (twice). Then I checked all the wiring that I could under the car to the point where it went into the body. Everything was good, but still a RR ABS sensor code, (along with ESC code and traction control code). I picked up a used ECM at the pic & pull for $20 figuring it would be worth a try, since I have tried almost everything else. I had no idea they were so vehicle specific.

 

OK, what was the ABS code, it would tell you which wire is at fault. Was it still pointing to RR after the replacement, or did you assume it did.

Most ABS faults will cause TC and ESC warnings & vicey/versy.

I have been fighting a similar problem for a while. I think mine is the yaw sensor, but the car is going away soon.

Have the airbags ever deployed?

 

The code was still pointing to the RR. I'll pull the codes again and post them here later today.

 

I have the ABS code. I was mistaken in what I was thinking about the number of codes. I only have one code, C0050. What I have three of are the messages on my dash when I start the car. They are "service esc, service traction, and service tire monitor. I know that I have a failed TPMS in the right rear tire, but I hope that's not tied into everything else. I've never seen that mentioned anywhere.

 

C0050 CHEVROLET Right Rear Wheel Speed Sensor | AutoCodes
Possible causes
- Faulty Right Rear Wheel Speed Sensor
- Right Rear Wheel Speed Sensor harness is open or shorted
- Right Rear Wheel Speed Sensor circuit poor electrical connection


I see no mention of ECU.
It's the circuit that's shorted or open. Usually that means the connector is bad/gummed up.

 

Yeah, low tire pressure will cause service ESC and service traction. So naturally, having a bad TPMS would do the same. Someone chime in if I'm wrong here. I've never been in that situation, but I've read others have.

 

he has not mentioned low tire pressure. That would cause TC, and ESC warnings because a low tire would rotate at a different speed from the others.

The rear ABS connectors are easy to mess up! Easy to not connect fully, easy to bend pins, easy to break a wire.