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Over the weekend I seafoamed my car, changed the oil, and put in new spark plugs. Ive done this a couple times before and its always gone smoothly and appeared to this time as well. Since then, Ive had a couple instances where I turn on my car and while it starts up ok, something is clearly wrong.

The CEL comes on and the traction control light. The car beeps and warns about the power steering, even though it seems to work fine. The real problem is that it feel like its shifting way harder and rougher. Switching into reverse was followed by a loud clunk as it shifted into gear, same thing when putting it back in drive, and then when it shifts gears its extremely rough.

So far, turning the car off and back on fixes the problem until it pops up randomly again.

Is this possibly a computer problem or did I maybe not connect something back properly or what?
 

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I wonder if it's the same problem as fl1000 in his thread "Traction Control Light Intermitent ".....Seems to be related to the TCM somehow. The TCM is right in front of the fuse block under the hood. Check that ground under the coolant reservoir, some people have writen this to be the problem. Try wiggling it to see if it's loose.Even if it doesn't look corroded it doesn't mean that the connection is good. Or if you played under the hood recently just check to make sure you didn't accidently disconnect a line,hose or connector.
 

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Did you ever figure out what was wrong? I have seen tons of these threads, but never any solutions. I'm still trying to fix my issue, which is the same, but nothing is working.
 

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TC Light

I have a 2005 Cobalt which has very few miles on it from Maine. The TC light came on the first time while in a parking lot and the car stalled. The next time I was on a busy street at 45 MPH and the car immediately downshifted and almost stalled. The problem became more frequent and the car power steering warning light, the check engine light also came on (codes 700 & 2100) and there was a clicking noise from the console shifter, which I suspect was the shifter lock solenoid. The most likely cause is a wheel speed sensor. There is no way to look at TC faults unless you have an expensive code reader which will access the ABS system. One thing to look at is the front axels. If they are covered with rust, this is possible cause. To test the wheel sensors, jack the car up and unplug the front wheel sensors. With a multimeter check the resistance at the sensor plug, it should be 850 - 1350 ohms,if it doesn't you need to replace the front wheel bearing assembly, which has the TC sensor built into it. With the meter still connected change to the AC millivolt scale. Rotate the wheel by hand you should read a value greater than 100 mv. If you don't the most likely cause is rust on the axel at the point where the axel disappears into the wheel bearing assembly. On the axel inside the wheel bearing housing assembly is flat spots with cutouts which make the axel have the appearance of a gear. The TC sensor pulses an output at the high point on the gear and nothing at the low point, giving you and AC voltage output. A rusty axel shaft only gives a high pulse and no zero output thus no AC voltage. I cleaned the axel by carefully inserting a thin narrow piece of sheet metal between the axel and the wheel bearing housing at the bottom of the axel and rotating the wheel clockwise looking at the back of the wheel. This cleaned up the rust between the axel and the sensor. This may take several tries to clean it up. After your done you need to blow the area out with compressed air, and with a clean rag clean the sensor. Now test the sensor by rotating the wheel by hand and checking the AC output voltage. If it passed the 2 multimeter tests above check the voltage going to the sensor it needs to be greater than 4.25 volts DC. If it isn't most likily cause is a broken wire or corroded connection. I finally found my problem after some time it was a poor ground connection on the ABS module. I ran a ground wire to the engine from the ABS module. The communications network between modules was being corrupted by electrical interference at the ABS module on the GMLAN high speed network. A tip to other people that they may have this may same problem, many different things were happening which were not related to the ABS, such as the power steering would wink out, the solenoid in the console shifter would go on and off. These and other problems didn't always occur at the same time.
 

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Thanks for that info.If i get a traction control light again ,i will check for rust in that spot.......I haven't gotten any problems since the temp warmed up and after I cleaned and greased the connectors at each wheel and BCM connectors
 

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I have this same problem in my 2007 chevy cobalt. I brought it to the dealer numerous times and paid out the butt to have them fix it, only to have the problem resurface a few days later....It did seem to happen less and less as the weather warmed up though. Kinda strange.
 

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GM bulletins say they must add an extra ground wire between TCM and engine.
 

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I have this same problem in my 2007 chevy cobalt. I brought it to the dealer numerous times and paid out the butt to have them fix it, only to have the problem resurface a few days later....It did seem to happen less and less as the weather warmed up though. Kinda strange.
gearbolt,
Had you ever worked with Customer Assistance to have us follow up on the multiple trips you made in to have this concern looked into? If you would like for me to look into this further, please get in touch via private message.

Best,
Sarah
GM Customer Service
 

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RE: Cobalt electrical problems

Sarah (GM Customer Service) --I tried to PM you, but being a new member and under 10 posts, they will not let me so I guess I will just post the message.
------------------------------------------------------------------------

Sarah,


I did not really know there was anything more I could do about this issue so I just kinda have been trying to drive with it. It's only slightly annoying until the power steering completely fails, which makes the car very hard to control.

I had brought it to the chevy dealer, in forest lake, where I bought the vehicle. The first time I brought it in, they stated it was just a loose connection on the battery...they went ahead and tightened it and charged me a couple hundred for labor. The problem then resurfaced about 4 days later. Brought back to shop and they said it was an issue with "loss of communication". They ended up changing out the entire ignition, which they said the problem was coming from. Charged $100.00 dollars more because the bumper to bumper covered the repair but needed deductible.

Problem resurfaced about a week later, but by the time I was able to bring it back in for service, my warranty had expired and I didn't want to have to pay another large fee for labor because they stated they could find the problem but it would be very expensive due to the amount of time needed for electrical labor.

I loved the vehicle until this problem started happening. I thought the dealer I bought the vehicle from would help me with this issue but it sounds like they have no idea how to fix it so I am just stuck driving a vehicle that is extremely unsafe to drive but I have no other choice.

Can you help me with this problem? Please contact me via email at your convenience.

/Sincerely,

B. Powers
[email protected]



gearbolt,
Had you ever worked with Customer Assistance to have us follow up on the multiple trips you made in to have this concern looked into? If you would like for me to look into this further, please get in touch via private message.

Best,
Sarah
GM Customer Service
 

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I have problem with my ABS & Traction Control lights coming on intermittently ? Problem seems worse when raining. Connections have been cleaned & put grease on as per one post here. Front & rear brake pads have been changed. Any insight into this would be appreciated.
 

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Year? Engine? Does it come on when driving normally? My traction control only comes one when i have to swerve around some morons. My ABS never comes on though.
 

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You might want to clean and verify ground G101 to make sure fastners are tight and contact is good. This ground is right below to the right of the ABS module on the sub frame. What other symptoms have you noticed? Does your wipers seem to lose power. Is the drivers side headlight dimmer than the passenger side or does it flicker?
 
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