HELP! Truck in the shop for 8 weeks and will not accept a tune

Mr. Demeanor · January 5, 2019

Just before Thanksgiving I took my 2005 Hummer H2 into a very reputable shop for some repairs, mods, and a full dyno tune.

Engine is a 6.0 with headers/full exhaust, Trailerblazer SS intake and 90mm TB.

The maintenance and mods were completed in a day and then the trouble started.

I had previously obtained a tune based on some mods from Blackbear Performance. When this shop attempted to connect to my ECM it "died". They thought it was just a bad ECM and got another. They installed it and the same thing happened. When they connected it killed the ECM.

I have talked to several shops as have they. The consensus is that a module is communicating at the same time which will kill the ECM. They have disabled everything they can and the problem persists. Onstar, Stereo, something about the transfer case module was suggested, etc. etc.

If anyone has experienced something like this and has input I would greatly appreciate it.

tbarn · January 5, 2019

You can't "kill" an ECM by just communication unless that communication is programming. So, they put a new GM ECM into it and tried programming it? With a new ECM can you communicate with a scan tool before programming?

Mr. Demeanor · January 5, 2019

10 hours ago, tbarn said:

You can't "kill" an ECM by just communication unless that communication is programming. So, they put a new GM ECM into it and tried programming it? With a new ECM can you communicate with a scan tool before programming?

No the second PCM was a used/refurb.