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Hey all. I'm hoping some electrical specialist can help me with my problem.
I replaced the alternator and battery in my '77 vette less than a year ago, however I am currently having more power issues. The Gen light continues to flick on and off while driving, and when the system is under load, power is noticeably drained with the head and cabin lights dimming. The battery doesn't start without a jump, however I'm not sure if it would stay dead if I was positive the alternator was charging it. The lower red cable (I've attached a picture of it in the spoiler, but I can't figure how to resize the image) is tight, however the connection point "jiggles" when moved. I'm not sure if this is routine with these alternators. It also appears like the insulation of this wire melted some. The ground line was previously loose and is now retightened. My voltage gauge reads steady around 12-13 when the car is started after a jump. When the RPMs are 35+, the Gen light goes off and voltage goes around 16-18.
I'd appreciate any help anyone could offer. I'm not the biggest mechanic -- especially towards electrical systems.
calig
I brought in your "spoiler" picture....
Now then.... you need to GO DISCONNECT YOUR BATTERY and fix then lead on this output terminal lead.
Don't go replacing anything other than this lead. That is one mess that you DO NOT want touching the alternator case.
If it was mine I'd repair with a new lug, some soldering, and heat shrink.....but if that option is not within your capabilities then just go get a new lead, same gauge, and replace it. ENSURE that it does not touch the alternator anywhere than where it attaches to the post.
After you repair, or replace, that lead we can then evaluate your charging system performance.
Here's the terminal that needs replacing. To replace it requires removing the alternator from the car and disassembling it. With alternator light flickering I suspect the diode trio has gone bad and maybe the rectifier bridge. Repair the wire and replace the alternator.
The shop test confirmed the voltage regulator was bad. Everything should be wired correctly.. when I previously changed the alternator, I didn't rewire anything so it should be the original wiring setup. The insulation did melt. I'll be changing out the wires and connections that are damaged as well.
Thank you everyone for the suggestions. I'll report back tomorrow once everything is swapped out.
Another thing to check. And something that can cause a voltage regulator to fail. In addition to repairing that positive wire. The alternator actually grounds through the engine block. Not that little ground wire on the case. And there is a heavy ground wire from the block to the frame right in front of the starter and over to the idler arm. On my 77 that ground cable had gone all green and corroded. When I replaced it. My charging system suddenly started working heaps better!
Update: I replaced the alternator, battery, and rewired the power output on the alternator. Gen light is staying off and voltage is sitting 16-17. Driven it around and it's been looking solid.
You may have a bad connection on the 2 wire connection on the alternator if your voltage is that high. Your battery will overheat and might explode if you continue to drive it with such high voltages.
As others have stated, 16 - 17 volts is way too much. I had that happen to me back in the 70's with a '72 Camaro I had at the time. Cooked the battery. Smelled like rotten eggs.
1977 battery/electrical issue
