PCM will not accept a tune and kills PCM.
01-04-2019, 08:14 PM
#1
PCM will not accept a tune and kills PCM. No Camaro but I do have a 6.0 Hummer H2 and thought someone here might be able to help. Seems to be a pretty active tuning forum.
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.
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.
01-04-2019, 09:47 PM
#2
I've experienced this on full size trucks / SUV's with aftermarket alarms and / or stereos and it's a known issue. I would think a Hummer would be in similar territory. Do you have an aftermarket stereo or alarm system installed? If so, do you have the door chime or radio interface for stereo controls on the wheel? Get rid of them and try again. If that is the case the PCM isn't dead, it just won't fully read / flash properly. If you are using HP Tuners it should be able to recover the PCM once the problem is cleared. I bench flashed one guys PCM until I figured out what was causing all the drama.
01-05-2019, 08:39 AM
#3
I've experienced this on full size trucks / SUV's with aftermarket alarms and / or stereos and it's a known issue. I would think a Hummer would be in similar territory. Do you have an aftermarket stereo or alarm system installed? If so, do you have the door chime or radio interface for stereo controls on the wheel? Get rid of them and try again. If that is the case the PCM isn't dead, it just won't fully read / flash properly. If you are using HP Tuners it should be able to recover the PCM once the problem is cleared. I bench flashed one guys PCM until I figured out what was causing all the drama.
01-05-2019, 11:29 AM
#4
I was just thinking the stereo has a separate module for the door chime and steering wheel controls I believe. The said they pulled all the fuses for the stereo but could that device be on a separate circuit?
01-06-2019, 09:07 AM
#5
When I said "get rid of them" I wasn't referring to pulling the fuse, I was serious. Get rid of them. Get them COMPLETELY out of the circuit. I don't care if you re-install them later (I'm not a music guy so that stuff ends up in the trash if I buy a car with it) but as long as you are tuning they need to be gone.
Years ago I wasted way too much time trying to tune a guys truck that had a bunch of aftermarket radio crap and there were only two things that worked: removing and bench flashing the PCM (sucks) and removing the connectors to his aftermarket radio junk. The first time I ran into this I probably burned an hour or more more playing with fuses and troubleshooting other stuff (besides thinking my stuff was broken) before I did what I should have done in the first place. I pulled the radio bezel off and disconnected every bit of aftermarket radio wizardry under the dash. Afterward I reconnected my interface and flashed a new cal in record time. Now I don't even waste time or take a chance I just disable the junk first and save us both a lot of agony.
Years ago I wasted way too much time trying to tune a guys truck that had a bunch of aftermarket radio crap and there were only two things that worked: removing and bench flashing the PCM (sucks) and removing the connectors to his aftermarket radio junk. The first time I ran into this I probably burned an hour or more more playing with fuses and troubleshooting other stuff (besides thinking my stuff was broken) before I did what I should have done in the first place. I pulled the radio bezel off and disconnected every bit of aftermarket radio wizardry under the dash. Afterward I reconnected my interface and flashed a new cal in record time. Now I don't even waste time or take a chance I just disable the junk first and save us both a lot of agony.
01-06-2019, 10:16 PM
#7
When I said "get rid of them" I wasn't referring to pulling the fuse, I was serious. Get rid of them. Get them COMPLETELY out of the circuit. I don't care if you re-install them later (I'm not a music guy so that stuff ends up in the trash if I buy a car with it) but as long as you are tuning they need to be gone.
Years ago I wasted way too much time trying to tune a guys truck that had a bunch of aftermarket radio crap and there were only two things that worked: removing and bench flashing the PCM (sucks) and removing the connectors to his aftermarket radio junk. The first time I ran into this I probably burned an hour or more more playing with fuses and troubleshooting other stuff (besides thinking my stuff was broken) before I did what I should have done in the first place. I pulled the radio bezel off and disconnected every bit of aftermarket radio wizardry under the dash. Afterward I reconnected my interface and flashed a new cal in record time. Now I don't even waste time or take a chance I just disable the junk first and save us both a lot of agony.
Years ago I wasted way too much time trying to tune a guys truck that had a bunch of aftermarket radio crap and there were only two things that worked: removing and bench flashing the PCM (sucks) and removing the connectors to his aftermarket radio junk. The first time I ran into this I probably burned an hour or more more playing with fuses and troubleshooting other stuff (besides thinking my stuff was broken) before I did what I should have done in the first place. I pulled the radio bezel off and disconnected every bit of aftermarket radio wizardry under the dash. Afterward I reconnected my interface and flashed a new cal in record time. Now I don't even waste time or take a chance I just disable the junk first and save us both a lot of agony.
Ill talk to the shop. Thanks. Monday is 9 weeks.....
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01-07-2019, 01:57 PM
#8
Don't over complicate things. If pulling radio and onstar fuses doesn't solve the issue, just unplug the ECU and flash it on a bench harness.
A bad battery is a more likely cause than anything else.
A bad battery is a more likely cause than anything else.
01-07-2019, 08:42 PM
#9
I believe tomorrow or hopefully soon they are pulling the dash off and disconnecting the stereo and door chime/steering wheel adapter.
06-27-2021, 04:24 PM
#16
I have a 2003 Tahoe and I have this same issue.
I have a pioneer with steering wheel controls.
Tried to write a tune and it failed.
Now car won't start, HPTuners won't read it, scanner won't read it.
New Battery.
Pulled fuses....ABS, radio, TBC, etc.....Same result....Nothing....Detect Protocol error.
HPTuners support has been no help.
So I bought a bench harness off amazon.
Any feedback on this one?
I would dread pulling my radio out to disconnect the harness and SW controls module....sheesh....I'm not that good of a tuner, it may take me 5 or 6 times to get it right....LOL
I have a pioneer with steering wheel controls.
Tried to write a tune and it failed.
Now car won't start, HPTuners won't read it, scanner won't read it.
New Battery.
Pulled fuses....ABS, radio, TBC, etc.....Same result....Nothing....Detect Protocol error.
HPTuners support has been no help.
So I bought a bench harness off amazon.
Any feedback on this one?
I would dread pulling my radio out to disconnect the harness and SW controls module....sheesh....I'm not that good of a tuner, it may take me 5 or 6 times to get it right....LOL
06-27-2021, 06:42 PM
#17
The reviews on that product are not good. 
You can make one yourself for less money, though it will might some time to collect the parts and put them together.
Building a Benchtop PCM Tuning Harness - GM Truck Central
I didn't bother with a switch, I just plug and unplug as needed.
The power supply is only tricky part - some wall-warts work and some don't. You need something that can provide at least 1 amp without voltage dropping, and you need clean power. I haven't used this one but it looks promising because you can set the voltage to something in the 13-14 range to give you more headroom than typical 12v power supplies.
You can make one yourself for less money, though it will might some time to collect the parts and put them together.
Building a Benchtop PCM Tuning Harness - GM Truck Central
I didn't bother with a switch, I just plug and unplug as needed.
The power supply is only tricky part - some wall-warts work and some don't. You need something that can provide at least 1 amp without voltage dropping, and you need clean power. I haven't used this one but it looks promising because you can set the voltage to something in the 13-14 range to give you more headroom than typical 12v power supplies.
06-27-2021, 08:00 PM
#18
Thanks for the input.
Do you know of any off-the-shelf bench harnesses that work well?
I don't mind buying a good one.
HPTuners has enough issues without me having to worry about stereo steering wheel control interference.....sheesh.
Do you know of any off-the-shelf bench harnesses that work well?
I don't mind buying a good one.
HPTuners has enough issues without me having to worry about stereo steering wheel control interference.....sheesh.
06-27-2021, 08:36 PM
#19
TECH Fanatic
It is quite possible your PCM is temporarily bricked but can be recovered. There is a pin on the printed circuit board that needs to be grounded at the instant the PCM is powered up. This allows a program such as "LS Droid" or "PCM Hammer" to quickly upload a small boot kernel program to take control of the PCM which then allows the main operating system to be reloaded.
You Tube has a few videos covering this topic. Bench harness required and you must remove the lid on the PCM.
Rick
You Tube has a few videos covering this topic. Bench harness required and you must remove the lid on the PCM.
Rick
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06-28-2021, 12:24 AM
#20