have a 2009 Hummer H3 that was diagnosed as having a severe trans slip, only occurs after driving several miles and at temperature, cold ok. We replaced the transmission with a reman GM unit and drove. It started to act up again... Looked at a scan tool and found that the H3 is pulling timing due to knock, no knock sensor codes and appears sensor is working. Any ideas on what it could be. we have filled the truck up with new fuel as well, no change.

 

OK. So as to get the correct terminology for my sake I believe when you refer to pull timing you are perhaps talking about advancing or retarding timing? If the trans is replaced and it is truly a good known working 40L60e then your next step will be to look at cam/crank on a scan gauge II or equivalent type scanner. I'd be most interested in what the different values of each is as well as the ecu/pcm is recording /stating for different modules. The trans is controlled electronically so that needs to also be looked at. What are the values, do they match a known good H3?
This should be a good thread to follow...

 

I will update as I get more information. 2009 H3 is in Texas, I am in Michigan, so this is a pain.. over 115K miles, When vehicle is driven over 20 minutes it acted like the trans was slipping, took to a Dealer and said trans is bad. Picked up vehicle and has a shop replace trans with a GM reman unit ( my fault for not asking for a second opinion) Son went to pick up H3 and started to act up again. Shop checked and scan tool shows vehicle is pulling timing when hot, no codes, yet. Shop did what I asked them to do, which was replace trans, flush cooler, program TCM, change F/R diff fluids and transfer case fluid. Vehicle drove from Michigan to Texas no issues. has new plugs, new crank sensor and new VLOM sensor, new air filter and new belt. Any ideas? Shop wants to start by draining fuel and putting premium in, I said may not be a fuel issue as we have filled it twice since it started to act up.

 

How does the shop's scan tool show the "H3 is pulling timing due to a knock"? You are stating some conclusion given to you instead of telling us what the shop was actually looking at. Makes zero sense to me.

Does your son get any messages in the DIC, like "reduced power" etc....

Where did you get a VLOM sensor for an H3??????

 

it is the Camshaft Position solenoid, not VLOM. I am in Michigan and not getting alot of information from the shop in Texas. Unfortunately I am at a loss and I hope someone knows of someone in Houston that knows H3 vehicles, would gladly move there. they stated that timing is pulling 10 degrees and riding the knock sensor, that is what he stated.... So again Im not there to go see

 

Working on an H3 is like working on any Chevy. There are only a very few items specific to the H3 that might get by any capable mechanic, and your problem is not one of them.

I would like to help, but I just need more info/answers.

Good luck.

 

moved H3 to the Dealer, will advise once I get a proper diag

 

after all the diagnosis, may have come down to a bad trans control module. Once it is replaced will verify all issues are corrected. I am actually happy if this fixes it as I hate wiring issues..