Car is a 1996 Firebird 3.8 5 speed with a 1997 PCM swapped in. I'm using DHP and an AVT box. It has worked flawlessly many times flashing the PCM, and I even flashed the PCM on another F-body as well. Yesterday I was doing a lot of trial and error with the timing map, must have flashed it 3 times and never an issue.
Today it really let me down though. I tried to flash the PCM this morning and DHP gives me a warning - Voltage at 11.7 volts, close to the 11.5 minimum. So I cancel the write, and start the car to run it for a few minutes to charge up the battery. I drove the car yesterday and if I remember right, the voltage was at 12.1 for all the PCM writes.
A cold front had moved in last night. It was around 90 degrees yesterday, now it's 60 degrees. That's all I can think of as to why the voltage is lower. It's a recently new battery. The car cranks over strong, no sign of the battery being bad at all.
Anyway, after a few minutes of charging I shut the car off and try the write again. Now the voltage is 11.8. It's in the green and DHP doesn't give the warning anymore. Half through the write I get some error. Shut it off and try to start the car, it won't. Fuel pump doesn't prime when turning the key. Try to write again, can't establish connection, try to read dtc's, can't establish connection, try to scan vehicle, can't establish connection. With all that I'm pretty sure I bricked the PCM. Anything I can do to bring it back?
I'm kind of scared now to even do a PCM write in the car ever again. I have an offboard programming harness I made and a good power supply to run it with. I suppose it would be a pain to have to undo the PCM connector every time, but I guess a bricked PCM is more painful.
Either that or I need to connect a battery charger to the car to ensure good voltage during the write, but even then I'm not sure that's as good of a solution as the offboard harness.
I think I screwed up in another way too. This whole time I've been doing "full" writes. Maybe I should have been doing partial "writes" (the calibration parameters only?) Does that prevent a bricked PCM when you're just making fine tuning changes?
