# ECM Issue U0100 and P0700 Negative Cable



## jpavlik (Dec 22, 2016)

Hello everyone, thanks for hearing me out. Recently started having issues with my 2011 Chevy Cruze w/70k miles and have read a few posts here about it but looking for some definitive answers.

About a week ago, the Stabilitrack and Traction control messages came on and then shortly after the check engine light came on as well. This was intermittent, would shut off and then come back on. The last time, all three lights/messages stayed on, gauges were jumping (temp and RPM), car was not shifting properly and was not accelerating properly. I took it straight to the dealer. I asked them to look at the bulletin for negative battery cable as I had read about it on this forum. They said this was the issue and replaced the negative battery cable and put in a new battery as well. They said that this cleared most of the codes but they needed to put in a new battery to test/clear the rest of the codes. I found this strange as I had just put in a new battery in February, but let them put in a new one anyway. I took the battery back to AutoZone and they tested the battery; found nothing wrong (12.43v, 74% charge, normal wear). Dealer said they were lying, but I don't see why they would as the battery had a warranty; they just give you a new one. Anyways.......... the very next day after getting the car back with new battery and negative cable all the same issues started again. Car is back to having Stabilitrack messasge, traction control message and check engine light. I threw on a diag reader and got U0100 and P0700 as codes. U0100 being ECM communication issue and P0700 issue being TCM communication. This leads me to believe that there are some issues with the ECM. I have read on forums that some dielectric grease on the connection to the ECM can help but I am not sure this will be a true fix. 

The car is at the dealer again now and I want to avoid them replacing parts until the issue is cleared and spending days going back and forth to the dealer. I know it is cheaper for them to just replace a part than spend the time to diagnose this, but this will only cost me way more money. Negative cable replacement seemed to work for most people but that is not the case here.

Is there anything I can have them try? Has anyone figured out the root cause of the issue? Any help is much appreciated.


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## obermd (Mar 3, 2012)

My guess is they either didn't replace the cable like they said they did (focused on up-selling you an unneeded battery) or they didn't do the job correctly and didn't get the new cable properly torqued into place.


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## jpavlik (Dec 22, 2016)

Is there a way to very this?


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## jpavlik (Dec 22, 2016)

And actually, right after I posted that the dealer called me. They want me to come into the shop tomorrow to meet with a special "tech" they have coming in from some special GM service who is going to have to do a "drag" test on all the electrical lines. Dealer stated that the PCM has about 16-17 codes stored and this is the next step. They think it may be the aftermarket cruise control put in (which they put in the day I bought the car). I requested this as part of negotiation as I was doing lots of highway back then.


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## ChevyGuy (Dec 13, 2014)

Anything that plugs into the car's communication bus is suspect. I wouldn't blame the dealer a bit if he wanted it disconnected - just to see if the problem went away.


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## jpavlik (Dec 22, 2016)

I am not blaming the dealer, sorry if it came off that way.

Had a meeting with the dealer, tech and few managers with 4 possible solutions but they were not sure if any would work for sure. The dealer had called a master mechanic with high rating for these solutions:

1. Manipulate fuses and harnesses for ECM while monitoring (basically put stress on them and shake/press) to see if any issues with connections.
2. Put dielectric grease on the connections to ECM.
3. Take out aftermarket cruise control
4. Remove ECM unit and place in freezer to simulate cold weather and heat up for overheating. Test and monitor at each. 

Solution #1 did not produce any changes/drops in voltage nor did it produce any error codes. Solution #2 is currently being tested and have driven the car for 30 miles with no issue yet. If issue happens again the dealer wants to move on with solution 3 and 4. 

Thoughts and feedback welcome.


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## obermd (Mar 3, 2012)

So your fuse box is good. As an IT professional I've seen servers go wonky when electrical connections aren't good and the dielectric grease is a good way to fix this type of issue. It sounds to me like the GM tech who's assisting them at this point knows what he's doing when it comes to troubleshooting.


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## Chevy Customer Care (Oct 29, 2011)

jpavlik said:


> I am not blaming the dealer, sorry if it came off that way.
> 
> Had a meeting with the dealer, tech and few managers with 4 possible solutions but they were not sure if any would work for sure. The dealer had called a master mechanic with high rating for these solutions:
> 
> ...


Hey jpavlik,

We're sorry to hear about this ongoing concern you've been experiencing with your Cruze, as we certainly understand how this is frustrating. However, we're glad to see that your dealership is working to resolve this for you. If you would like an additional layer of support as you work with your dealership, feel free to shoot us a private message and we will be happy to assist.

Chelsea D.
Chevrolet Customer Care


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## jpavlik (Dec 22, 2016)

Just over a month has gone by and I wanted to provide an update. We went with the dielectric grease on the ECM connections and the car has been running fairly well. There seems to be some hang in early gears up to nearly 6000rpm and the Stabilitrak/Traction Control light has came on twice. Both times it was for a few seconds and then went right back off; sitting in ATM for one and at stoplight another. At the same times, car learched forward while foot was down on brake.

To me, this says connection issue and the dielectric grease was helping. Maybe apply more? I have seen a few others post on this as well.


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## Blasirl (Mar 31, 2015)

jpavlik said:


> Is there a way to very this?


Should look like this now: 

Picture of new negative cable



jpavlik said:


> Just over a month has gone by and I wanted to provide an update. We went with the dielectric grease on the ECM connections and the car has been running fairly well. There seems to be some hang in early gears up to nearly 6000rpm and the Stabilitrak/Traction Control light has came on twice. Both times it was for a few seconds and then went right back off; sitting in ATM for one and at stoplight another. At the same times, car learched forward while foot was down on brake.
> 
> To me, this says connection issue and the dielectric grease was helping. Maybe apply more? I have seen a few others post on this as well.


Just putting on the dielectric grease without cleaning the contacts can be hit or miss. The very act of unplugging and re-plugging the connector will remove some oxidation and / or other contaminants, but if possible you should use a pencil eraser on the contact surfaces, and then ensure you don't leave any eraser residue. If that is not possible, after reading the precautions, use some electro-solve or LPS contact cleaner. I say read the precautions so as to ensure it won't degrade the plastic or other materials in the vicinity. Oh and do this in a well ventilated area as well.


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## jpavlik (Dec 22, 2016)

Back again.... all the same issues started again. I have read a few posts that suggest valve cover replacement to fix stabilitrack error. Thoughts?


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## jpavlik (Dec 22, 2016)

Just read the codes again today and received two additional.
U0100
P0700
P069E
C0301


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## mikestony (Jan 17, 2013)

This is so odd I ran across your thread as I think, or had, the same issue.
See my post here with the video and tell me if this is what you were experiencing, as I have the same first 2 codes thrown at me.
I wonder if we are in the same boat, and mine was just a fluke when I did my trans fluid change.
http://www.cruzetalk.com/forum/129-...sion-fluid-flush-post2822130.html#post2822130


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## jpavlik (Dec 22, 2016)

YA it's pretty similar. It gets worse at times to where the teams won't shift and the Digital MPH and average MPG gauge goes "--"

Here is video of mine in a similar issie but this video does not show all the issues at one time:

https://youtu.be/8PS6svu5UrM


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## jpavlik (Dec 22, 2016)

You will also notice the steering wheel move without me doing anything.


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## mikestony (Jan 17, 2013)

jpavlik said:


> You will also notice the steering wheel move without me doing anything.


Oh my! That steering wheel moving is a little bizzare!
I'm not an expert by any means but just throwing this out there....have you checked the tightness/cleanliness of the battery negative cable and other grounds?
I had a brief message on my dash about the "service power steering" with the idiot light, but that went out after about 5 seconds. 
So weird of an issue.


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## jpavlik (Dec 22, 2016)

I have not checked the grounds, but the negative cable was replaced so assume cleaned. Which grounds and any idea how many/where??


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## mikestony (Jan 17, 2013)

jpavlik said:


> I have not checked the grounds, but the negative cable was replaced so assume cleaned. Which grounds and any idea how many/where??



I just followed my negative cable that led to the chassis, and you'll see some grounds there.


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## Robby (Mar 1, 2013)

Keep in mind that Chevrolet is using the same crimping method (solderless) on the replacement cable and the strong possibility of a recurrence exists.

So, just because it is new doesn't mean it is good......it just means the new one has less resistance because it is new.
There will be secondary failures that occur over time, not to all cables, but it will happen.

(This design is not specific to GM.....every manufacturer is using a similar arrangement on some of their models, however, the results of high resistance will not be the same as the Cruze exhibits).

Rob


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## jpavlik (Dec 22, 2016)

Is it possible that this could be some sort of conflict with aftermarket cruise control or Viper autostart?


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