Bricked PCM....damn!

[scubasteve231]

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?

[Fivefingerdeathpunch]

With HP Tuners you can recover the computer if you write calibration and you get an error or battery voltage problems. You'd disconnect the battery for a little bit, hook it back up and with a charger on the battery write calibration again.

If you do a write entire and the flash completely fails the computer is junk and can't be recovered.

[JamesIvey24]

Make an off-boad. I bricked two pcms before I built an off-board. Did I mention you should build an off-board. While you being all geeky, make an off-board. And finally, make an off-board.


EDIT:

USE the off-board you've got.

[scubasteve231]

Darn, that's learning I guess.

So I do have a 1998 PCM that I bought thinking that one day I would re-pin the PCM connectors and run it. Maybe this is the time do it.

Do you know where I could find wiring diagrams of the actual PCM connectors for a 1997 and 1998 ?

[Scottydoggs]

i get that low volts warning every time, click ok and flash it. as long as your batterys not 100% crap and will drain faster then 5 minutes.

turn off all lights too. parking lights are a killer.

should the program crash or fail in some way, DO NOT TURN THE CAR OFF. reboot the pc and dhp and reflash, it will notice things went wrong last flash and ask you questions. ive saved 3 pcm's this way so far. key is to not turn off the power to the pcm, once you do that its over. ala brick.

you can run a battery charger while flashing the car if need be.

[scubasteve231]

I'm leaning towards re-wiring the PCM connectors for the 1998 PCM since I already have the PCM and it's forward progress. The scary part is just making sure I have correct information to begin with as far as the connector pin outs, and that I get them all in the right spot.

I went through the tuning dropbox and I found a file "97 00 Bonneville PCM Connectors.xls" and it's basically what I wanted to make. Author is "Bill Bostick", is that someone active here?

It lists the PCM pins for both years, and shows the new pin number where that wire would need to go. Perfect. Has anyone used this file to help them do a 1997 to 98+ PCM swap and was the information correct?

[Scottydoggs]

thats billboost37 here. not as active as he used be. its his drop box we all share freely. its good info. his how to's are bout the best you'll find on 3800 cars.