Corvette 1999 after the latest cam swap I have compounded an existing problem. For the last few months after hitting a bump in the road the gauges would go crazy. Half would max out and the other half would go to zero. I figured the PCM was going bad since I also had the dreaded leaking Delco battery a few years back. Anyways after the cam swap we loaded a tune via HPT and started the tuneing process. After the third upload the PCM seemed to vanish and on the DIC the error message No Comm. was displayed. I jumped the gun a found a PCM vendor and purchased a new PCM fpr 98.00USD and installed the unit. To my amazement on a stock tune the car actually started and drove. Now the problem gets ugly, connected the HPT up and started to up load and Bam No Comm on the DIC agian. I am now having the new PCM reflashed and plan on running the car for a day to let new codes surface and hopefully let the car tell me where the problem is. Have the GM service manuals and a Volt\Ohm meter so the testing will begin. Has anyone had an issue similar?

 

Well, from what I've read on corvetteforum.com, the C5 is plagued with lots of ground problems. I'd doublecheck everything, as well as taking a really good look at the pcm connectors to make sure the battery acid didn't corrode the pins any.

 

Pins look good, and good point. I am leaning towards the BCM module supplying a positive to ground on the serial bus. Once I get the new PCM in I will be able to check the two Star connections for voltage, where ther should be none. Just puzzled why the PCM would go into a No Comm error and not reset...

 

Check the ground on the back of the Drivers side head...your problems sound VERY familiar