# Car won't start or crank, U0100 - U0101 - already replaced battery



## trax (Dec 19, 2015)

Hi guys, first post here.

I've had my 2012 Cruze for almost three years and driven it to 58K miles with absolutely no issues. It's been about as problem-free as I could ask for.

I recently started working from home, and I haven't driven my car in over a month. I decided to sell it, but yesterday when I went to start it, it wouldn't crank.

When I try to start it, there is no activity from the starter. The DLC shows the following messages:

Service Stabilitrak 
Service Traction Control 
Power Steering 
Fuel Level Low (I am 100% sure there is just under half a tank of fuel left. The odometer hasn't changed since I last drove the car) 

The interior of the car is fully operational -- all BCM-related stuff seems to work (windows, lights, door locks, stereo, HVAC, trunk, wipers, etc.). But the car simply won't start. I'm also puzzled by the fuel gauge reading zero.

I replaced the battery today with a brand new 600+ CCA unit from AutoZone, but this didn't fix the problem. 

I used a code scanner and got the following codes:

ECM U0100 
TCM U0101 

While I can successfully clear the ECM codes, when I try to clear the TCM codes, I get an error and the codes stay.

I stopped by a local dealership and their service desk was kind enough to print out a small pile of documents regarding the U0100 and U0101 errors. Based on GM document 2133282 ("DTC-U0100-U02FF") it sounds like the issue stems from a faulty ground to either the ECM or TCM, or an issue with the serial data connection between the modules.

I did some initial troubleshooting such as confirming that the ECM is getting a good ground, but it started getting dark and bitterly cold, so I stopped for the evening.

I plan on going through the rest of the procedure tomorrow to check the B+ and ignition circuit terminals for the ECM.

*Questions:*

Where is the TCM located on these cars? I saw a few connectors on the transmission itself but it wasn't clear if they go back to an external module other than the ECM. 
Are there any other troubleshooting steps I should try besides the voltage / continuity tests listed in the GM document? For example, is there some trick like cutting battery power or pulling specific fuses for a certain amount of time to "reset" everything? 
 

Thanks!


----------



## ChevyGuy (Dec 13, 2014)

U0100 means that communication with the Engine Control Module has been lost.
U0101 means that communication with the Transmission Control Module has been lost.

I'd do the following:
- Check the voltage drop from the battery terminal to the chassis ground. Replace battery ground cable if it's more than 0.01 Volt.
- Disconnect the battery, wait awhile and reconnect. Things may have gotten messed up by the low battery and didn't reboot properly.
- Look for signs of mice or squirrels that might have chewed some wiring.

Having these codes in history is not usual. Make sure they are current codes. They can be set during troubleshooting.


----------



## autopcms (Jan 7, 2016)

Get some technicians who can come with the booster cables and try to start it. Also, you can reach out to your dealers to check the engine control modules as well.


----------



## ChevPete (May 13, 2017)

What was the problem? I realize this is an old post but I am having the exact same problem with an 08 Malibu. Car was fine , stopped it for a few minutes then that was it. No crank, all messages on the dash for PS, brakes, etc. no gas gauge. Code U0101 that comes back instantly after being cleared. No security light on, Fuses good, tried swapping relays. I have power to the supply side of the relay but nothing on control side, starter does work when jumped. This car did have a severely coroded neg. battery terminal that basicly was just sitting there. Not sure if this could be the cause? I have checked/unplugged connectors at tcm, ecm, etc. Any help would be appreciated. This seems like a common problem but have not seen definate solutions. Thanks


----------



## Eddy Cruze (Jan 10, 2014)

ChevPete said:


> What was the problem? I realize this is an old post but I am having the exact same problem with an 08 Malibu. Car was fine , stopped it for a few minutes then that was it. No crank, all messages on the dash for PS, brakes, etc. no gas gauge. Code U0101 that comes back instantly after being cleared. No security light on, Fuses good, tried swapping relays. I have power to the supply side of the relay but nothing on control side, starter does work when jumped. This car did have a severely coroded neg. battery terminal that basicly was just sitting there. Not sure if this could be the cause? I have checked/unplugged connectors at tcm, ecm, etc. Any help would be appreciated. This seems like a common problem but have not seen definate solutions. Thanks


Have you tried the Chevy Malibu Forum?

Chevy Malibu Forum: Chevrolet Malibu Forums


----------



## ChevPete (May 13, 2017)

Yes, thanks. Just seeing the exact same issue on a Cruze i figured it would be the same problem with the Malibu.


----------



## jstahliv (Apr 13, 2016)

I just got this code the other day on my 2012 cruze. Any updates on what it was?


----------

