Electrical Problems (tcm, ecm, bcm, wiring and grounds)
01-14-2014, 10:10 AM
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Electrical Problems (tcm, ecm, bcm, wiring and grounds)
Hi everyone I'm new here but been driving a cobalt for a few years now with very little problems until the resent winter months. I was shocked to discover all the cobalt owners experiencing the same problems we were and to be honest thought I got stuck with a car prone to bad electrical problems before I had it paid off which made it unusable in the cold and really unsafe for my family. Thankfully there were several forums out there where people discussed the problems which helped me to boil down the symptoms and do some good troubleshooting in order to effectively narrow down the problem. I would like to thank and give back by sharing my experience as there were a lot of people posting however you didn't get to hear much about success, just dead ends and problems.
01-14-2014, 10:13 AM
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2006 chevy cobalt ls 2.2. London, ontario, Canada. 101000 kms on the vehicle.
Mid December 2013. Weather conditions -10c snowing.
Wife is driving the car to work and stops at an interception and waits to turn left. Roads are a bit messy with loose snow and as she goes to accelerate when the following happens.
Dashboard shows no gas, nothing on speedometer. Car begins to chug like it has no power. The power steering, gas and brake peddles are functioning normally.
Wife takes her foot off the gas and attempts to accelerate again. Dashboard reads normal again but the car jerks when the automatic transmission climbs up from 1st to 2nd and so on. She is only a few blocks from work so she continues on and parks at work. The next morning the car starts fine, everything appears normal on the dash.
As winter continues to introduce itself the problem happens again and again. When it's colder out, snowing and the roads are a bit of a soup of slush and snow the car demonstrates these problems off and on. We do find by shutting the car off for a few minutes seems to make the transmission stop jerking when it climbs gears. This doesn't prevent the dashboard errors from happening but it seems to reset the transmission in some way to stop the jerking until the next time the dashboard gives those problems.
I start to think that it's an electrical problem but worried that problems with the transmission may be the root cause of the electrical system demonstrating these problems.
We take the car to a transmission place and just our luck, the car is not demonstrating these problems. We ask him to go ahead and check the transmission pan and do a partial flush with fluids and filter. He says the tranny is in great shape, with little to no shavings in the drop pan. He did finally catch the car being stupid while taking a drive to run the fluids through it. He was smart and had his system tester plugged in when he drove it which told him the engine control modules and transmission control modules were producing error codes not only from themselves but that the was a communication error as well. This got me thinking, was it the road that was too beat up (wiring) to talk to the modules or the modulates themselves. After all, the modules are tucked away far more than the transit system of wiring and ground connections as they are exposed to the elements far worse and this does seem to happen when the roads are a mess and it's colder out.
The transmission specialist thinks it might be the 3rd control module, the body control module as he feels it's unlikely that 2 others have gone bad and wants to do some swap tests with connections he has at the wreckers. He can't do any of this today but says he will follow up on Monday.
The transmission mechanic didn't follow up however the weather improved and the problem stopped until after Christmas when it got worse.
A late December evening it was getting colder out again, it was snowing and the roads getting soupy. We had no problems until after a few stops. We were about to leave a parking lot when the dashboard did it again except all the gauges and warnings weren't recovering. Sure the car was still going but this was getting scary so we pulled over before driving onto a busy street and shut the car off.
We let it sit for a few minutes and tried to start it up with no luck. Just dim lights, a slight electrical sounding hum and all the same error messages on the dash plus the check engine light. (Power steering, low fuel and gas/RPM gauges all at zero.) No clicks, nothing struggling to turn over.
Our bother in law came out to give us a boost and boost it we did. From the boosting terminal and directly from the battery in the trunk of the car it wouldn't start. The error messages did go away but the car just gave that slight electrical hum and won't start.
I ran a few chores while waiting for the tow truck to come and after about an hour came back to the car to wait. Just for laughs I tried to start it and wouldn't you know it, the error messages were gone and it started. I threw it in reverse and tried to get it in a better place for the tow truck. I drove it about 5 feet and it stalled. I turned it off and tried again, no luck.
When the tow truck came it started again but the dash board quickly gave me new error messages. (Check sys electric) and (Battery saver mode on). The tow truck driver was quick to blame my battery as the car was towed to Canadian tire.
When we got there the car was brought into the warm garage and say there for about 40 minutes. They ran the electrical test and found the alternator checked out ok but battery was finished. The battery was replaced and it ran like a dream. Started right away, no warning errors nothing. I don't know how in depth the $40 electric test is at Canadian tire so either the warmth of the garage and disconnection of the battery must of set right whatever other electrical problems in the car back or the test just does the bare bones basics of electrical cause it was just the battery was the problem according to them.
The next day (Sunday Jan 5th) it was starting to get cold and wet again but the car ran fine all day with several stops made with it. That night we got hit with the big snow storm and blowing winds bringing the temp down to -40c.
Monday morning came and we were in the same boat the night we had the battery changed. The car wouldn't start, just a slight electrical hum with a check engine light on, gauges reading zero with a low fuel and power steering warning. Because this problem was so interment I started looking online once again and found several cobalt owners in the same boat as me. Some even after getting starters, tcm and bcm's changed. Cobalt owners had done research (some who worked in part stores and shops) and found the grounding rods were terribly exposed to the elements under the car and during extreme weather conditions the filthy grounds would finally give and cause these shorts generating these errors.
http://m.topix.com/forum/autos/chevr...L6037FC4NHV/p5
Oddly enough someone at work asked me if I ever got a shock when I get in and out of the car. I explained that quite often yes I would as I would have one foot on the ground and grab the door frame of the car and a lot of the times would get a shock. The person then told me that my car wasn't grounded properly. Not knowing anything for certain but but it did help to cement what people were saying online even more though.
I went out Monday night managed to get the car started after several attempts the car decided to start but still gave me all the error messages on the dash with the weather being -40c. I used a set of booster cables to attach one of the ground ends to the black metal bar holding what looked like a piece of stone in front of the battery boosting post in the front of the car and connected the other end to several other grounding points on the car with no luck. The error messages still remained on the dashboard. So that was a bust. Maybe the gauge of wire was wrong, maybe I didn't have a good enough connection, I don't know.
I would put the car in gear and try to get the thing out of the snow that was surrounding it and it seems every time I gave it some effort and the tranny would need the change gears it would stall just like it did the night the car was towed to Canadian tire. I left it for the night.
Tuesday January 7th I went down to get the car started again due to -40c weather I didn't want the car not to start due to the cold. It started without error but the check engine light was still on. I let the car run for a bit, the error messages came and went twice. I managed to get the car out of the snow and it only stalled on me once and moved to a better spot. Between getting the car out of the snow, revving the car up considerably and the idling it ran for about 30 minutes. I did notice something else strange however for the first time. When i first got the car started I pressed the button to force the air circulation inside the car to get heat through all the vents and warm up faster (sorry I don't know what it's called but it's on the bottom of the console on the right next to both the rear defroster and A/C buttons) and the light just flashed 3 times at me and wouldn't come on. I tried again 15 minutes later and it came on just fine with a solid yellow light and I could hear the air being forced around through the vents. I looked it up online and found that this feature is also tied in with the BCM.
Breakdown:
- problems did not start nor do they happen unless it's cold, and/or wet snow.
- transmission is fine so is the alternator and the battery is brand new.
- all errors appear to related to a control module in the car however how could all three cause problems at the same time.
- could be something in relation to the control modules. Possibly grounding or wiring that links all these things together is the root cause. I'm sure if a scanner is connected it's simply going to say there is a problem with and communication to the various control modules. Everything else seems to be symptoms of a greater root cause.
Mid December 2013. Weather conditions -10c snowing.
Wife is driving the car to work and stops at an interception and waits to turn left. Roads are a bit messy with loose snow and as she goes to accelerate when the following happens.
Dashboard shows no gas, nothing on speedometer. Car begins to chug like it has no power. The power steering, gas and brake peddles are functioning normally.
Wife takes her foot off the gas and attempts to accelerate again. Dashboard reads normal again but the car jerks when the automatic transmission climbs up from 1st to 2nd and so on. She is only a few blocks from work so she continues on and parks at work. The next morning the car starts fine, everything appears normal on the dash.
As winter continues to introduce itself the problem happens again and again. When it's colder out, snowing and the roads are a bit of a soup of slush and snow the car demonstrates these problems off and on. We do find by shutting the car off for a few minutes seems to make the transmission stop jerking when it climbs gears. This doesn't prevent the dashboard errors from happening but it seems to reset the transmission in some way to stop the jerking until the next time the dashboard gives those problems.
I start to think that it's an electrical problem but worried that problems with the transmission may be the root cause of the electrical system demonstrating these problems.
We take the car to a transmission place and just our luck, the car is not demonstrating these problems. We ask him to go ahead and check the transmission pan and do a partial flush with fluids and filter. He says the tranny is in great shape, with little to no shavings in the drop pan. He did finally catch the car being stupid while taking a drive to run the fluids through it. He was smart and had his system tester plugged in when he drove it which told him the engine control modules and transmission control modules were producing error codes not only from themselves but that the was a communication error as well. This got me thinking, was it the road that was too beat up (wiring) to talk to the modules or the modulates themselves. After all, the modules are tucked away far more than the transit system of wiring and ground connections as they are exposed to the elements far worse and this does seem to happen when the roads are a mess and it's colder out.
The transmission specialist thinks it might be the 3rd control module, the body control module as he feels it's unlikely that 2 others have gone bad and wants to do some swap tests with connections he has at the wreckers. He can't do any of this today but says he will follow up on Monday.
The transmission mechanic didn't follow up however the weather improved and the problem stopped until after Christmas when it got worse.
A late December evening it was getting colder out again, it was snowing and the roads getting soupy. We had no problems until after a few stops. We were about to leave a parking lot when the dashboard did it again except all the gauges and warnings weren't recovering. Sure the car was still going but this was getting scary so we pulled over before driving onto a busy street and shut the car off.
We let it sit for a few minutes and tried to start it up with no luck. Just dim lights, a slight electrical sounding hum and all the same error messages on the dash plus the check engine light. (Power steering, low fuel and gas/RPM gauges all at zero.) No clicks, nothing struggling to turn over.
Our bother in law came out to give us a boost and boost it we did. From the boosting terminal and directly from the battery in the trunk of the car it wouldn't start. The error messages did go away but the car just gave that slight electrical hum and won't start.
I ran a few chores while waiting for the tow truck to come and after about an hour came back to the car to wait. Just for laughs I tried to start it and wouldn't you know it, the error messages were gone and it started. I threw it in reverse and tried to get it in a better place for the tow truck. I drove it about 5 feet and it stalled. I turned it off and tried again, no luck.
When the tow truck came it started again but the dash board quickly gave me new error messages. (Check sys electric) and (Battery saver mode on). The tow truck driver was quick to blame my battery as the car was towed to Canadian tire.
When we got there the car was brought into the warm garage and say there for about 40 minutes. They ran the electrical test and found the alternator checked out ok but battery was finished. The battery was replaced and it ran like a dream. Started right away, no warning errors nothing. I don't know how in depth the $40 electric test is at Canadian tire so either the warmth of the garage and disconnection of the battery must of set right whatever other electrical problems in the car back or the test just does the bare bones basics of electrical cause it was just the battery was the problem according to them.
The next day (Sunday Jan 5th) it was starting to get cold and wet again but the car ran fine all day with several stops made with it. That night we got hit with the big snow storm and blowing winds bringing the temp down to -40c.
Monday morning came and we were in the same boat the night we had the battery changed. The car wouldn't start, just a slight electrical hum with a check engine light on, gauges reading zero with a low fuel and power steering warning. Because this problem was so interment I started looking online once again and found several cobalt owners in the same boat as me. Some even after getting starters, tcm and bcm's changed. Cobalt owners had done research (some who worked in part stores and shops) and found the grounding rods were terribly exposed to the elements under the car and during extreme weather conditions the filthy grounds would finally give and cause these shorts generating these errors.
http://m.topix.com/forum/autos/chevr...L6037FC4NHV/p5
Oddly enough someone at work asked me if I ever got a shock when I get in and out of the car. I explained that quite often yes I would as I would have one foot on the ground and grab the door frame of the car and a lot of the times would get a shock. The person then told me that my car wasn't grounded properly. Not knowing anything for certain but but it did help to cement what people were saying online even more though.
I went out Monday night managed to get the car started after several attempts the car decided to start but still gave me all the error messages on the dash with the weather being -40c. I used a set of booster cables to attach one of the ground ends to the black metal bar holding what looked like a piece of stone in front of the battery boosting post in the front of the car and connected the other end to several other grounding points on the car with no luck. The error messages still remained on the dashboard. So that was a bust. Maybe the gauge of wire was wrong, maybe I didn't have a good enough connection, I don't know.
I would put the car in gear and try to get the thing out of the snow that was surrounding it and it seems every time I gave it some effort and the tranny would need the change gears it would stall just like it did the night the car was towed to Canadian tire. I left it for the night.
Tuesday January 7th I went down to get the car started again due to -40c weather I didn't want the car not to start due to the cold. It started without error but the check engine light was still on. I let the car run for a bit, the error messages came and went twice. I managed to get the car out of the snow and it only stalled on me once and moved to a better spot. Between getting the car out of the snow, revving the car up considerably and the idling it ran for about 30 minutes. I did notice something else strange however for the first time. When i first got the car started I pressed the button to force the air circulation inside the car to get heat through all the vents and warm up faster (sorry I don't know what it's called but it's on the bottom of the console on the right next to both the rear defroster and A/C buttons) and the light just flashed 3 times at me and wouldn't come on. I tried again 15 minutes later and it came on just fine with a solid yellow light and I could hear the air being forced around through the vents. I looked it up online and found that this feature is also tied in with the BCM.
Breakdown:
- problems did not start nor do they happen unless it's cold, and/or wet snow.
- transmission is fine so is the alternator and the battery is brand new.
- all errors appear to related to a control module in the car however how could all three cause problems at the same time.
- could be something in relation to the control modules. Possibly grounding or wiring that links all these things together is the root cause. I'm sure if a scanner is connected it's simply going to say there is a problem with and communication to the various control modules. Everything else seems to be symptoms of a greater root cause.
01-14-2014, 10:29 AM
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I found a good mechanic with the help of a friend who took his time with the scanner and try one thing at a time. While the extreme cold hasn't come back yet the car was still demonstrating communication errors when he got his hands on it (just not enough to make the car conk out) and with tracing from the control modules he found that the grounds needed replacing, and several wires networked from the modules that were in rough shape and replaced them. After using the electric grease and checking the condition of the control modules the communication errors stopped. He let it sit all night, ran it and tested again every time in between and nothing has come up so far. Are we in the clear, maybe we won't know until the next cold snap however I know what will need replacing if it does happen again (control module). The point is to find someone who isn't just going to throw parts at problems, they can and will take the time to back track and troubleshoot. Remember that communication errors will happen and scanners are good for showing that but it doesn't always indicate what the root cause is. Make sure whoever looks at your car starts with the simple things first and works their from the ground up (literally). I've read far too many people replacing control modules which are expensive and quick from what I understand by dealerships to blame and still have the same problems shortly afterwards. Finding someone who will slow down and do the right troubleshooting will save you time and money so don't be afraid to ask questions and make sure they are not just going to hook a scanner up To your car and start pointing fingers at every little error.
I will continue to post how the car is doing and wish I could throw the video I took of the symptoms on here. Someone has a great one they did on YouTube. Just google video search (chevy cobalt tcm) and it will come up. Il. Try to post the link. Thanks to everyone.
I will continue to post how the car is doing and wish I could throw the video I took of the symptoms on here. Someone has a great one they did on YouTube. Just google video search (chevy cobalt tcm) and it will come up. Il. Try to post the link. Thanks to everyone.
01-16-2014, 10:03 AM
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http://youtu.be/TVf3M0E0S8g
So I ended up posting my own video to YouTube of what our car was doing. This was shortly before that giant polar vortex hit North America in Jan 2014. I ran out to start the car everyday when that hit to make sure if the car wasn't going to start it wasn't because of a frozen battery. I have a video of the car actually going form normal to its problem state during that cold snap I'll post to YouTube later on.
So the warm weather is starting to wind down so we will know soon enough if the car is completely fixed. So far zero problems to report back. Again, thank you so much to everyone who takes time time to throw these things online to help other people out. Just trying to give back.
So I ended up posting my own video to YouTube of what our car was doing. This was shortly before that giant polar vortex hit North America in Jan 2014. I ran out to start the car everyday when that hit to make sure if the car wasn't going to start it wasn't because of a frozen battery. I have a video of the car actually going form normal to its problem state during that cold snap I'll post to YouTube later on.
So the warm weather is starting to wind down so we will know soon enough if the car is completely fixed. So far zero problems to report back. Again, thank you so much to everyone who takes time time to throw these things online to help other people out. Just trying to give back.
Last edited by kirklandkonnect; 01-16-2014 at 11:12 AM.
05-03-2014, 03:41 AM
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I know this is a partially old thread but I am having the same problem and haven't found a solution or seen anyone with a definite solution.. I came across this while looking and everyone should check it out.
https://www.cobaltss.net/forums/showthread.php?t=190918&styleid=10
I just find it kinda odd that aloot of cobalt owners are having the same problems and everyone just throws new bcms and pcms In their vehicles when this is a common problem
https://www.cobaltss.net/forums/showthread.php?t=190918&styleid=10
I just find it kinda odd that aloot of cobalt owners are having the same problems and everyone just throws new bcms and pcms In their vehicles when this is a common problem
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