2003 LB7 Won't Accept Program

[custom8726]

Check to see if you have any wires spliced into the purple wire under the dash at the OB2 connector. I had a similar issue once.

[illinoischris]

Thanks for the replies so far. The unit of course has power, and can communicate with the truck, I can do the diagnostics and see fuel pressure, throttle pos, etc. It just the PCM unlocking that doesn't work. One more thing it does is immediately after pressing "Y" to tune, and it shows the "Unlocking PCM", the dash including gauges, info center and dummy lights "reset" similar to shutting the key off and on again. This lets me know the unit is "talking", but alas, the error occurs.

From the replies it sounds like two votes for EFI Live. I hate the thought of buying another programmer, after two purchased with zero results, I need to sleep on that one.

[C-Power]

well if you decide to get efi.... you can throw your PPE this way

[smav]

I have a 2003 duramax and was attempting to get a bullydog to down load and it gives me the same problem. During the unlocking PCM stage it comes up with an error stating it cannot communicate with PCM. The gauges work and I can get the codes if something fails, the VIN comes up correctly but it will not do the down load. I tried it on a ford and it worked like clock work. I also have tried it by leaving in the fuses, pulling the ones it states and also pulling any other fuse that wouldn't be related to the PCM. Same error everytime. I checked the 2 grounds, signal and power wire on the DLC and all are good. It also resets all the guages as you posted once it comes up with the error that it cannot communicate with the vehicle.

[illinoischris]

I hear you. Mine is the same way, everything on the truck is working and i can read diagnostics, reset the trans, but not download. I have tried about every combination of fuse pulling possible, had the dealer flash the pcm, etc, still not working. I have basically given up for now, i have not gotten any good ideas from anyone.

[mijdirtyjeep]

You could call the person you bought it from and see if you can return it. The Vender I bought mine "Quad Stealth2" on from here even sent a pre-paid box VIA UPS. I do not know how long you have had it or if you even bought it new, but if new and it has been just a short period of time it might be worth asking.

[C-Power]

haha yeah just dont sent it to quadzilla.........cheap bastards.......the first one i had to send back to schied......i had to pay shipping b/c they sold me junk.....second time to quadzilla same thing i had to pay for it to be shipped all the way to texas b/c thier junk product.......its BS......

[KingV]

I was having this problem with my 03. I had a Power Pup and tried a ATS EPower and neither would load so I figured it was time for EFILive. When I got EFI I tried reading the ECM and it would get a bootloader error so I posted on their forum and found out my ECM was corrupted by the dealer. I installed another ECM and now it works like a charm. I read that GM's TIS programmer will corrupt the ECM when things go wrong during a TIS reflash.

[lubeman1969]

Is it possible your current files are "locked" by some sort of programmer now and has to bew set back to stock before any other can be used? You may have already addressed this and I missed it.

[smav]

I was thinking along the same lines as Lubeman, that the program may be locked out. It also could be corrupt as well. I have experianced a Ford dealership doing that to some of our work trucks where they went to flash it and they ended up haveing to order and install a new PCM or ECM because they couldn't write to it. I am kind of a miser and a little hesitant to take it to the local chevy dealer as I don't want to spend the money to have them update or flash the PCM just to find out it still doesn't work. It would be different if a guy knew exactly what they were looking for, (I.E. is it locked or corrupt).