Newbie speedo/fried brain ? etc help

[Randy]

Hi I am new to all this I just posted in the introduction forum. I have a 94 Chevy PK retrofitted with a 94 model Caprice LT1 engine with a 16188051 service number brain. I have the TunerCat tuner, $EE def file and ALDLCable.com USB adaptor cable.
My initial brain was in stock mode, it ran halfway decent but rather doggy and was off about 10mph. After first burn while just barely after take-off maybe 15mph my speedo pegged all the way out (85mph) I had set tire size, gear ratio, etc. Then decided to do the math and set the speedo by the rev's per mile of tire, and it still pegged. Any help on this ?
Also now have a communication problem. I had no problem getting it to communicate and read the PCM initially but after doing about 6 burns on the same box I got an error to commuincate stating PCM not responding. And after the last burn truck only hit a couple times and would not start. I disconnected power to PCM and rebooted laptop and double checked port settings with no joy. I have a spare PCM so I connected it and got it to work with it. Can I somehow revive the first brain ? Or is it fryed ? If it's fried wonder what could have happened ? Nothing different happened while burning it than before. I have not tried to short it out and erase it yet. Would that be an option ?
Since i am new and quite dumb at this would it help to have someone send me a calibration file that is working for them so I can at least have a good start point ?

Thanks Randy

[Monodax]

You mentioned that the old PCM stopped communicating. Did this happen after a failed write attempt meaning did it stop somewhere in the middle of the flash and display an error message?

If it didn't you can always try doing what you did before and re-powering everything back up and trying one last time. If the flash chips are corrupt there is not really an easy way to fix the problem as it goes back to the way the 8051 and similar PCM's are designed. The flash software has to communicate with the PCM in order to start the flash process. Since the 8051 PCM's are one segment if the flash process fails it corrupts the flash memory so that you have incomplete code/data. When the PCM powers on it tries to boot up and start the main processing loop. If the data/code is corrupt it cannot boot up therefore it is similar to formatting a PC, installing windows and halfway through the install pulling the CD/DVD out of the drive. It would leave the PC in an unknown state which would very likely not able to boot up.

If you can get access to a Tech-II from a GM dealership it may be possible to get it communicating again but this is not guaranteed.

There is a flash fix page if you have access to a soldering iron/heat gun. You would need to get access to a flash programmer but if you get the chips off usually someone that has one will flash it for you if you send the chips to them for a small fee. They would need the base code for both chips which I have attached to this post to get the PCM communicating again. You would then need to solder the chips back on the boards and put it back together. I generally recommend socketing this style of PCM if something like this happens. It makes it much easier to repair if it happens again later.

The Flash Fix Page is below:
How to fix the PCM Flash Memory

Best Regards,
James

[Randy]

The PCM that won't communicate was accually running after I had programmed it. I tried to re-program it and it failed to communicate. I tried it again last night with no joy by disconnecting the power and letting it set for a while.
I do have an extra brain box though and have ordered another used one to play with. Thanks for the info.
By the way if you have a calibration file for a 94 model I can play with I'd appreciate it.

Randy

Originally Posted by Monodax

You mentioned that the old PCM stopped communicating. Did this happen after a failed write attempt meaning did it stop somewhere in the middle of the flash and display an error message?

If it didn't you can always try doing what you did before and re-powering everything back up and trying one last time. If the flash chips are corrupt there is not really an easy way to fix the problem as it goes back to the way the 8051 and similar PCM's are designed. The flash software has to communicate with the PCM in order to start the flash process. Since the 8051 PCM's are one segment if the flash process fails it corrupts the flash memory so that you have incomplete code/data. When the PCM powers on it tries to boot up and start the main processing loop. If the data/code is corrupt it cannot boot up therefore it is similar to formatting a PC, installing windows and halfway through the install pulling the CD/DVD out of the drive. It would leave the PC in an unknown state which would very likely not able to boot up.

If you can get access to a Tech-II from a GM dealership it may be possible to get it communicating again but this is not guaranteed.

There is a flash fix page if you have access to a soldering iron/heat gun. You would need to get access to a flash programmer but if you get the chips off usually someone that has one will flash it for you if you send the chips to them for a small fee. They would need the base code for both chips which I have attached to this post to get the PCM communicating again. You would then need to solder the chips back on the boards and put it back together. I generally recommend socketing this style of PCM if something like this happens. It makes it much easier to repair if it happens again later.

The Flash Fix Page is below:
How to fix the PCM Flash Memory

Best Regards,
James