I've done all the research and diagnosing I can but now I'm stuck and need some expert advice. I recently bought a 2002 C5 Corvette from a friend. It runs really well but has electrical issues.

The problems:
The DIC always reads High Oil Temp, Reduce Engine RPM, and High Voltage
When you turn it on the gauges all sweep and occasionally work for about 10 seconds and then all the dial gauges go dead. No amount of thumping on the dash will turn them on or off.
Buttons on the right side of the IPC don't do anything
No door chime
Radio doesn't turn on but I assume that is a separate/unrelated issue

Here's what I've done so far:
New Battery - Voltage is about 12.5+
Plugged in code reader to OBDII port - no codes pending or stored
Took oil temp wire off of sensor - no difference
Pulled fuse 19 - no noticeable difference
Pulled fuse 25 - The IPS went dead
Fuse 19 and 25 voltages are very near what the battery voltage is
Inspected the BCM connectors - All looked good
Took apart the BCM and had one small spot of corrosion around a solder point – cleaned it really well – no difference
Pulled apart both Star connectors, cleaned and checked for continuity – no difference
When Star connector 2 is pulled it doesn’t do anything different
Pulled the IPS out and took it apart and inspected all the connectors and ribbons - Everything looked nearly brand new and all the male and female pins were straight and tight – no difference
The only odd thing I noticed on the IPS was a small burned spot in the corner of the digital display but the display itself seems to work fine.
Took apart the ignition switch (the contacts were corroded) – cleaned and polished the contact – no difference
Took apart and cleaned all the chassis and ground points under the hood – no difference
I think it’s also odd that I still don’t get any codes even after disconnecting the battery I don’t even get a P1000 code.

I feel like I’ve tried everything that I’ve been able to find on the forum that are common issues. Please let me know if I've missed anything.
It seems to me I may have a bad IPS or BCM. Is there a way to confirm which one is bad? Thanks in advance for the help.

 

I don’t know if your code reader can communicate with all the modules but that would be the first thing I’d check..if you have the wiring schematic I would look at power and grounds for the IPC...you always start there !!

 

Since generic code readers won't be able to read the extended module and the fact that the DIC cannot be used to get any of the codes, you need to get a Tech2 or a Tech2 clone or the VXDIAG VCX Nano to read and test the IPC. The VCX Nano is around $100 on Amazon. It interfaces with a laptop and it can do almost everything that the Tech2 does. Without one these tools you won't be able to troubleshoot your issue.

 

Thanks for the replies. I have a friend that has an expensive two way scanner. I'll see if I can use that to diagnose it. I also found a diagram for the IPS connector and will test for battery power and grounds. Thanks and I appreciate all the ideas.

 

try opening the driver side door when this happens again