Last week I hosed the PCM in my Vette flashing it. Since then I removed the Flash chips, soldered sockets to the PCM board, purchased 2 new chips preprogrammed with my PCM's software (I have a backup). After getting it all back together at first it would not start. Then I rechecked all connections, everything is fine. Checked the program in the chips, perfect here also. Put it back together, still no start.

I then connected my Lapop to it and checked if TunerCAT could download the Flash. Yes, it could, and what it downloaded matched my backup file exactly. Tuner complained about a "Security Violation" before the download that seemed to clear itself. After the download the car would start and run fine, no codes. It ran for 30 seconds, then stopped. At this point I noticed the "Security" light was lit on the dash, and the fans started in low speed. Then the VATS light went out, car would start, run longer this time. Etc. Etc.

The longer I left the battery connected the better it got. The VATS was kicking in randomly. Not it runs fine for at least an hour. Problem seems to have gone away.

Question...Does the VATS system have some sort of "learning" period? I'm 99% sure it's not the PCM, the solder joints and sockets connections are good. I'm wondering if leaving the battery disconnected for a couple of weeks would have cleared the CCM's memory?? Anyone else experience this?

Thanks

 

I have more information. I checked the codes again this morning, the PCM had no stored codes, the CCM had a historical code 52 (FEDS failed), and the TCS/ABS had a code 72 (Serial Comms Failed). I would say the FEDS failure is what was shutting the engine off. The TCS/ABS was most likely me screwing around with the serial bus with my scan tool/Tuner. I have not seen a PCM DTC 51 (PROM error) as of yet.

Following the procedure in the service manual for code 52 it leads me down a path that tells me to check for a bad connection on the serial line. If it was a PCM fault the PCM should have set a code also. If it was a VATS problem I should have a VATS code set also. I have no other code other than 52 which points to a bad connection.

It still seems to be running fine. I'm nervous about going anywhere with it without knowing what caused the code 52. I cleared the codes and will see if they reset.

 

I would slow the laptop port down......assuming it's the com port your using..........that might help....... :confused: