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Hello Corvette Forum. Happy to finally be a Corvette owner. I've worked on all sorts of Vettes as I'm a personal mechanic for a guy that owns 30 Corvettes. Mostly C2 and C3.
Few days ago I acquired a 2000 FRC. All was good until today.
After leaving my house I got a "High Voltage" light on the dash. Then it went away immediately. Watched the voltage meter and didn't see it go past 15. Then drove 2 miles, no issue. Later in the day, the instrument cluster completely shuts off, comes back on, shuts off again, comes back on again. Engine stayed running as normal. Cluster stayed on and I get traction control and ABS lights on dash. Take it home and shut off. Before I could pull the codes I moved the Vette to my backyard and the TC and ABS lights disappeared.
Upon a short diagnosis I find the alternator power wire has been cut. A new wire poorly routed to the fuse box. I find some wiring near the BCM or ECU has been altered/cut. Really bummed and just looking for some insight. I'm ok with electrical, but far from a guru.
See what DTC’s were set…what alternator power wire are you taking about ??….the alternator B+ that goes to the starter ??
DTC is for the air pump. That was present before this all occurred.
Power wire as in the large gauge main power wire that goes from Alternator to the fuse box/battery area.
Edit: the large gauge red wire in the photo below was uncovered and still hot. Meaning it still had power. I wrapped some electrical tape around it so it doesn't short anything out.
The power wire was run from the alternator, over the top of engine, directly to the B+ terminal at the fuse box.
Last edited by Superdave1.0; Jan 17, 2022 at 11:53 PM.
The alternator B+ goes to the starter as well as the battery positive cable..they meet at the starter !!
Good to know, thank you. Now if the B+ wire was still hot, why in the world would someone cut the wire at alternator and run a new wire straight to the B+ terminal??
Good to know, thank you. Now if the B+ wire was still hot, why in the world would someone cut the wire at alternator and run a new wire straight to the B+ terminal??
Found the positive battery terminal wiring is incorrect. It has been replaced with a black negative terminal instead. Looks like I'm in for some trouble with this car.
Another update is I ordered the big 3 wiring from saccity corvette. I figure their alternator wiring has to be safer than the unfused wire I currently have.
Before test, battery fully charged to at least 12.6 volts across the battery terminals?
What kind of load? Most auto parts stores have a standard load test procedure.
If you measured 10 v across the battery terminals while cranking, not great but not terrible. 8v cranking would indicate a bad battery.
Set your battery tester to cranking test mode, then start the vehicle. Your tester will record the lowest voltage that the battery is able to maintain while the starter motor is working.
Make note of your battery's cranking reading.
Healthy batteries should maintain between nine and 10 volts during cranking. If your test shows less than nine volts, your battery is weak.
Before test, battery fully charged to at least 12.6 volts across the battery terminals?
What kind of load? Most auto parts stores have a standard load test procedure.
If you measured 10 v across the battery terminals while cranking, not great but not terrible. 8v cranking would indicate a bad battery.
Set your battery tester to cranking test mode, then start the vehicle. Your tester will record the lowest voltage that the battery is able to maintain while the starter motor is working.
Make note of your battery's cranking reading.
Healthy batteries should maintain between nine and 10 volts during cranking. If your test shows less than nine volts, your battery is weak.
Hello. I purchased/utilized a new Schumacher battery load tester. The analog kind. It applies a load with the press of a button.
I fear I am jumping in over my head. but thought it useful to point out how important the correct alternator output is with these cars. I'm not fool enough to offer much advice to a working mechanic, but it is an idiosyncrasy of the cars that often is overlooked, and might not be known if you hadn't been around these cars much.
Often a replacement alternator is fitted, with no problems, .............. until it throws a voltage outside of the computers ability to understand, and then you have computer issues that are tough to understand since everything seems ok, and the alternator is fine.
Probably this is already known, I only mention it because I so often read about this issue, primarily in conjunction with aftermarket radio installs, and since you are working in that area, just in case.
- Picked up new battery today, NAPA legend premium 78 800cca.
- Ordered new starter to alternator wiring. Silverado/Avalanche uses same gauge alternator wire (6ga with 10ga fusible link). I will be extending this wire to reach the alternator.
- SacCity big 3 wiring upgrade on the way.
- Will be purchasing a new or reman alternator immediately. K63 RPO code should mean I need a 110 amp.
So far it's fixed. The high voltage warning was coming and going more often until today.
Today installed:
- New alternator cable that I made. 6 awg w/ 10awg fusible link.
- Good condition original battery cables. Complete unit, no splicing. They ground to motor and frame, also give power to starter and B+ terminal.
- Found starter solenoid stud was broken/loose. Reman starter installed.
- Found vacuum line broken under battery. Fixed that.
My check engine light turned off by itself. Praying it stays off. It was P0410 which I read could be vacuum leak related. Reman NAPA alternator comes in tomorrow. Making progress and might have completely solved my issues, will see.
2000 FRC electrical issues, need help
