Dtc: U0073 calling all hummer techs
 

Hey guys,

I`m having a few issues with a 2008 Hummer H2. Basically, from time to time the check engine lamp comes on. When it comes on, occationally the car wont start. If I disconnect the battery, and reconnect it the engine will start again.

I checked for codes and these 7 re-occur every time the check engine lamp is on:


U0140- Lost communication with Body Control Module (in air suspension control, transfer case control module, fuel pump control module, electronic brake control module).

U0102- Lost communuication with Transfer Case Control Module (in air suspension control, electric brake control module).

U0101- Lost communication with Transmission Control Module (in air suspension control, electric brake control module

U0100- Lost communication with Engine Control Module (in air suspension control, transfer case control module, fuel pump control module, electronic brake control module).

U0121- Lost communication with ABS Module (in transfer case control module).

U0073- Control Communication Bus off (in fuel pump control module, electric brake control mocule).

B1259 05- Antenna ground circut shprt to battery or open

So far I have replaces the BCM, TCCM, ECM, and Danta Link Connector, and nothing has changed. Looking at the codes it seems like the issue could be with the wiring harness, perhaps relating to the Control Communication Bus, and that is the reason the modules cannot communicate with eachother? Does any one have any advice on this? I have access to Tech 2, and have throroughly read the car for all codes as well as a physical insopection of the wiring harness, and the above modules were replaced, and nothing is coming up.

Any insight is appreciated!

Cheers,
Isaac

Sounds like a bad ground?

Flex fuel sensor?

Thanks for the responses. I dont think this vehicle is equiped with a Flex Fuel sensor? I would have to look into it further. I found a TSB which apparently generated 6 of the 7 DTC`s I have been pulling, so I need to call GM to get some more info on that.

IDE pay the dealer to diagnose it & go from there...Is anything wet?

:D That would be the easy way out for sure.

Actually I work for an independant dealer in Japan. We imported this Hummer and sold it several years ago, and it has always been plauged with these electric gremlins. There aren`t any Hummer/ GM dealers around...

The TSB which I found that I believe relates to this issue is #: 08-08-49-010A, and was issued July 1, 2008. Does anyone here work for GM tech or at a Hummer service place and know what the solution to this TSB was? It gives three possible failing components; automatic transmission, digital instrument panel, and door locks/ latches. Based on what we have diagnosed it seems like either the instrument panel or the transmission are the cause. Anyone know what part of the trans in particular caused this TSB? Thanks for the help guys,

Isaac

And no, nothing is noticeably wet.

Well, I called GM tech support and about 10 different Hummer dealers and didn`t get much info out of anyone. Half of them wouldnt even admit that there was a TSB, and the other half said they couldnt give me any info on solutions for that TSB unless they themselves diagnosed it. I had one place suggest to check the wiring behind the parking brake petal, and I will do that the next time the car is in our shop.

If anyone out there works/ has worked for a Hummer dealer and is willing to give me any tips they may have learned while dealing with this I would appreciate it!

Thanks,
Isaac

I just pulled code P0800 from this Hummer, which means the TCM is telling the car toput the CEL on. Im guessing this means the Transmission is bad? The TCB I found for the car said that it was likely either the cluster or the transmission. I am replacing the cluster today. Anyone have any input?

Thanks,
Isaac

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