high or low voltage

[1chevy02]

my friend has an 03 lb7 he was triying to install a ppe tuner and the ecm locked down on him. I tried to reflash it and it would just say after initalizing the bootloader that the ecm voltage was to high or low. He took it to the dealer and they told him the ecm was fried. we repalced it and the new one does the same damn thing. btw we have tried new batteries, charger, no charger. we have tried it at every voltage possible from 11.5 to 13.8 and NOTHING makes a diffrence we have checked every fuse wire and added on accessory we can think of please HELP

[GMPX]

The only time I have seen this happen is when the ignition key was not in the full on position when programming, I know sounds silly, but it happens.

Cheers,
Ross

[1chevy02]

ive heard that too lol, but weve been working on it for two days and i made shure

[GMPX]

Is there any possible way you can program the ECM outside of the vehicle? Like on a bench harness, even if you had to send it off to somebody to test?
I'm not sure what it could be, maybe the ECM is missing a 12V input.
On the LB7 with the key on there should be 12V at the following pins -

Blue Connector
19
20
57

Clear Connector
44

Best check them out.

Cheers,
Ross

[1chevy02]

thanks ill try that

[1chevy02]

19 blue conector
44 clear conector

do not have any voltage with the ignition on and the ecm disconected
we replaced the ignition switch and tested the old one and i that was not it

[THEFERMANATOR]

Those 2 circuits according to my diagrams for an 01 are for ignition 1 voltage to the ECM. Check the relay and fuse for ignition 1. Also does your instrument cluster come on? My diagram shows it as being powered off of this circuit as well as the BCM. The 03 may be different in body wiring, but I believe the pinout on the ECM is the same. Also did you pull the fuses that PPE says to pull? If not this may be why the problem occurred.

[Philbilly2]

I cannot be much of help here all I can give you is what worked on a truck that I was tuning.

Had a 2002 LB7 trying to flash any tune possible on to it. I would not take anything at all.
I could not even communicate with the ECM if the key was in the on position. If you moved the key back one click I could talk to the ECM, lisence it but got a bootloader error and could never get past that point.

So I took the ECM out of that truck and installed it in another truck to try and start eliminating problems. When I put the ECM in truck #2, it took a tune on the first try.

So I put it back in the truck that it was origianlly from and he drove it home. The only problem was that the tune that I flashed onto is ECM was kinda a turd. So I told him just for the sake of to say that we tried it, I plugged in to the OBDII on his truck, turned the key to the on position and I can tune his ECM in his truck now.

So more or less I would have to say that somewhere in the ECM harness there was a wire that was not doing what it was suppose to be doing and by moving the ECM in and out of the truck it made it start doing what it is suppose to be doing.

[1chevy02]

finally got it running!!!!!!!!!!! he took it to a guy who worked at a local stealership and he worked on it after hours. it ended up being a fried fuse box:wallbash: no idea why it would suddenly do that but hes just happy to have it running now i have an extra licensed ecm to play with:grin: