who can unbrick 2005 Hummer H2 PCM? what happened?

[ccrp]

very weird happenings today. Had to work on two Hummers H2, both with maggies, both 2005's, on both tuning for Maggies was done as usual and the first one was done within a few hours and drives and runs great.

The second one took an awful long 20 minutes to do a read entire, I copied calibration parameters from first over and wanted to write calibration. No luck, no way to connect to PCM. All tricks tried like 20 minutes wait, PCM fuses pulled, NAV/Radio fuses pulled and so on - no way. Tried to flash stock file into it via Tech2 - same, no way to connect.

took a spare 2005 PCM, installed it, flashed stock calibration over it with Tech2, did a read entire, made changes to it as needed for the Maggie, did a write calibration and car starts and runs. OK we thought.............put it into gear drive 10 meters and it stalls and never ever I am able to connect to it.

same as above !!

WTF happened please?

[Christian GM]

hi,
I had the same problem when I modified the throttle body tables.
that froze up some PCM but not all. there is a note on the low of that tables that inform you about this issue.
just a tip for you, maybe is not your scenario

bye

[ccrp]

it ain't. I am aware of that and no ETC tables have been touched. No Throttle booster stuff either..........

just a plain Maggie tune with injector, ignÃ*tion and fueling changes for starters....

[Bill@HPTuners]

ETC tables were likely altered from stock and killed the pcm.

Additionally long read times are a HUGE red flag for issues to come. But in any event usually when the etc tables are adjusted the vehicle will run and even drive for a short amount of time before stalling, throwing codes, etc. from my experience.

[Pork Chop]

i just read an 05 H2 this morning and it took about 10 or so minutes to finish. im pretty new to this, but i wondered how long it SHOULD take? (my s10 takes about 2 minutes.) theres been some issues lately with it he said. the security was goin nuts a week ago and he said the engine wouldnt shut off, even with the key out... he pulled pcm fuses to shut it down and unhooked the battery for a while. says it has been normal since. i cleared codes and didnt change anything in it to see if he has any more trouble. he's had a hard time getting used to all the fancy electronics and theft system in it, so he may have just screwed it up, but who knows. he asked if i would just disable the anti-theft. ill give it a week and if he doesnt have trouble, ill go tinker with it some. spark tables and shifting is probably all.

[Bill@HPTuners]

2-3 minutes is pretty normal for P01/P59 pcm's, any longer and theres likely a wiring or battery issue putting you into low speed mode when reading.