Hey y'all, I bought a 2000 c5 corvette a year back, and it's been really good to me up until the end of September. I had problems with the old harmonic balancer, and at 115k miles it had never been changed. So the car went out into the driveway with the hood removed for a few days as I pulled the old one off and overhauled all tensioners, pulleys, belts, the water pump, and the timing cover seal since the old one was leaking a little. Well, I got her together a few days later, and the oil leak was delt with, but when I went to start I was met with a Christmas tree of lights on the dashboard (CEL, check gauges, traction control, and abs) along with reduced power, low fuel, and service car soon. I went against better judgement and tried to start the car I got no fuel pump prime for 2 seconds and the car cranked but no start. The tachometer, gas meter, and coolant temp light are not functioning as well. I immediately figured since the car was without a hood and it rained while I was working, possibly water got into a splice pack or corroded a ground. So i replaced every splice pack outside/inside the vehicle and lubricated with corrosion X, sanded down all grounds aswell and still no dice. Next tried unplugging the serial data 2 bus next to the PCM, didn't help so it's not the door modules. Then tried unplugging both data busses and jumping the pcm/bcm, still to no avail. Opened up the bcm, it looked perfectly fine and the carpet was dry as ever around it, regardless cleaned the contacts where it plugs in and put it back together. (still no fix) Next, I jumped the pins for the fuel pump relay, with the key in "on" it turned right on! Tried to start the car, but still nothing. Weird enough, the keys unlock/lock the car, but I haven't heard my horn @ all (don't know if that's relevant). I've tested all fuses, changed the relays around so it's not a bad relay, as well as taken my aftermarket radio out and power seats out to simplify things.

I bought a new pcm thinking that that has to do the trick, brought it to a shop to get programmed w/ my vin, installed it, and NO DIFFERENCE!!! Finally, bypassed the Vats system just in case it was a problem w/ the ignition cylinder, no help I'm losing my mind trying to find these electrical gremlins, especially when I wasn't wiring anything doing the harmonic balancer job. RECAP--- Sanded grounds/changed splice conns, changed pcm, bypassed vats, checked fuses, removed radio, switched relays, and got batt tested. I love this car, any help getting it back on the road would be greatly appreciated.

CODES:
PCM- no comm
TCS- no comm
BCM- BO502, BO507, B2482, B2527
SDM- U1000, U1016, U1040
IPC-no codes Radio- no comm HVAC- no codes LDCM &RDCM- no codes
A6 SCM- NO COMM
BO RFA- U1000

 

You should measure if all of the no comm modules get theire voltages and have good ground connections , both from battery (hot all times) and ignition key (hot in ON and START) using a scope or a multimeter .
Recommend starting with the PCM and the BCM

 

Thanks a ton, just got off work so I'll be probing soon. Whats with these 'old' corvettes and their electrical issues?? Already replaced all wiring from the battery to underhood fuse box and the starter, aswell as duplicated all engine grounds to rule that out aswell as cleaning them. Like i said water could've gotten into the pcm/tac module when it rained, although how likely is it that those systems finally kick the bucket NOW?? I've gotten my engine wet before and no problem, just doesn't make sense to me.

 

In my opinion the PCM and the EBCTM should handle raing from above due better enclosures better then the underhood electrical center (fuses/relays) .
First I would ensure that all moisture is removed under hood electrical center .
I guess your problem is cause by watreintrusion somewhere in the engine bay area.
To verify is alle important modules get proper voltages PCM (including tacmodule) and BCM.
The "reduced power" is mostly caused by problems within the TAC module system (throttle sensor , footpedal(appsensors) an the tac module itself .
Have you inspected the tac modules (black box infront of the PCM) regarding water intrusion ?


A Tech2 scanner or similar to verify communications with all modules would be useful ,

 

I just got around to probing the connectors due to rain last night, and me not wanting to worsen the problem. The TAC looks to be good. After probing the PCM connectors, I have good ignition voltage, but no battery voltage on both orange pwr wires. Based on the diagram you sent yesterday, the orange PCM wires go to fuse 23, which was good but had no voltage on either side upon probing. I tested the TAC wiring and had no ignition voltage (pink wire), further following the circuit to fuse 17 I had no power there either. The only TAC wire I had power on was the grey wire on the larger 16 pin connector.

Any advice on where to go next?

 

If you have no voltage to fuse 23 which is hot at all times and comes from the battery fuses 52,53,4,3, and 51 will not be powered and your horn will not work…fuse 17 (THROTCONT) will also not be powered because the same circuit that powers fuse 23 also powers the Ignition Relay 42…if ignition relay 42 is not powered you will not have power to the coil packs and injectors…you may have a fusebox issue.

 

Thank you I'll be taking apart the fuse box tonight. Anything particular to be looking for/any way to test once apart for good condt.?