Hi, I am a new member, I have a 2010 HHR LT 2.2 and I no longer have 1st gear or overdrive. I have the codes read and it came back that I have a bad TCM. I have searched the internet and also searched this forum and can not find any information on how to replace the TCM. Anyone on here do this before? It looks like the module is mostly self contained so it doesn't look like it will be difficult once I locate the darn thing. Any advise or instruciton would be very appreciated.

Thanks
Leenie

 

You may want to post up your trouble code numbers here.
Remember that trouble codes don't always point to "this is exactly the part that's bad". The codes are used for diagnostic purposes.
It may well be the TCM is bad, then again, maybe not.

 

Welcome to the site LeenieP, what firemangeorge said post your codes and lets see what you have , how is your mileage and warranty 2010 bumper to bumper was 3 years wasn't it? there are people to help with that and verify your issue

 

Welcome to the forum Leenie,

There is a wealth of information and a number of great members that are more than willing to assist you. If you need assistance discovering the details of your warranty, I can help you with that.

Marlea Wilson
Chevrolet Customer Service

 

to the forum Leenie!

To echo firemangeorge and Oldblue, post up the code/codes and we can see if the diagnosis is accurate, or if there are other faults causing the issues you're having.

 

Sorry for the delay posting codes, I guess I am not getting email notifications, I didn't think anyone replied.

I have the codes pulled on my car again. Here is what I got

P0700
Definition
Transmission Control Module requested mil illumination.
Explanation
The TCM has detected an emission related fault
Probably cause
Check other service codes first.

and

P0974
definition
1-2 shift solenoid (SS) control circuit high voltage
explanation
The TCM Commanded the SS on and off but the return voltage was outside expected parameters.
Probable cause
Open or short circuit condition
Poor Electrical connection
Faulty shift solenoid

Anyone have any idea where to start? Dealership said they would look at it but it sounds like my transmission and may cost around $3000. Can't do that.

So sad because I love my car.

 

Oldblue, mileage is out of the park, I have 130,000 on it already, I do a lot of driving, love my car and really don't want to lose it.

Oh and if it helps diagnose, my mileage has gone down from 32 mpg to about 24-25 mpg since this happened. Car runs and shifts fine, just starts out in 2nd gear so is really sluggish, no jerks for tranny slips at all.

 

You need to take it to a transmission shop. Nothing in those codes says anything about a bad TCM. Probably needs a solenoid or 2 replaced, if you can do fairly heavy duty work you may be able to do those yourself, but probably best left to the pros.

You could try looking at the electrical connections on the trans and TCM.

The TCM is one of the modules under the "Darth Vader" hood in front of the fuse box. It is easy to replace, but needs to be programed with a TechII Scanner.

Hard to tell what emissions related fault could be, without a specific code, but it's probably just because the gears aren't right. Could be you have a wiring harness problem causing both, see if the harness goes to both the trans and another sensor and check the wires.
Done spitballing.

The reason for bad MPG is.... wait for it......... no overdrive!

 

and i think your in Limp mode you should not drive it alot or you will burn out your clutch and that would not be good, sounds very close to my problem im having same codes!!
sounds like you are going to have to drop the trans like me and replace the 5 solenoids.
It would be stupid to just do 1 first gear they are cheap. labor is $$
jeff

 

Hey Jeff.......

The post is over 4 months old. And he hasn't responded, to his problem thread, even though he had visited several days after posting this thread.
Doubt if he will respond.