Alternator/electrical issue

[guyatou]

I recently made some changes to my 68 SRL and now I'm experiencing some weird electrical issues after. Not sure if it's related or not. I have a GM 60 amp alternator that's about a year old -- it was new, not rebuilt, with one wire connected to the white wire that leads to the ammeter. It has worked fine for the last year in this configuration.

I pulled the multi-gauge to replace the lens with glass this week. Pretty sure i got the two wires back in the right order. When I fired up the car after that, the ammeter flutters between zero and halfway up the + scale, and my turn signals don't come on most of the time. It seems to depend on RPM or maybe cornering -- I didn't drive it enough to fully test.

Also, on the way home this evening, I got a really bad screeching sound from under the hood that got louder at higher RPMs. Squeaky belt sound or a bad bearing in the alternator -- it was hard to tell. I pulled over and took a look, and everything seemed to be turning fine. At idle there was no noise, but if I revved the engine the sound came back. After two or three miles the screeching stopped, but the ammeter continued to flutter whether it screeched or not. The headlights and dash lights also slightly dimmed and increased in intensity along with the ammeter fluctuations, at least at idle.

Wondering if there's anything I should check before taking the alternator in for testing and replacement?

[Nissanman]

Could easily be a Voltage Regulator problem.
The screeching could be either alternator bearings or drive belt.

[guyatou]

The main VR is removed in this install, there’s one on board the alternator. Could it be the instrument cluster VR? Haven’t ever had this squeak before. There’s only about 5K miles on the belt and alternator. Belt looked OK by flashlight, I’ll look closer in the morning.

[Nissanman]

The cluster VR is only for the fuel and temp. gauges.
The internal VR of the alternator may be faulty if the charge is causing the amp gauge to fluctuate.

[jrusso07]

Shoulds like you have a short somewhere in the system. The screeching sound can come with the alternator under a heavy electrical load - like a short circuit (low resistance circuit) or a shorted cell in the battery.

Assuming you have a volt meter....Check battery voltage with engine not running. Check it again running at idle. The terminal voltage should be about 2 to 3 voltages higher at idle as compared to engine off.

You can turn on the ignition but not start the car and check turn signals - with signals engaged measure battery terminal voltage. If it is low, you have a a short somewhere.

Does alternator get hot after screeching?

[redroadster]

Test it now ..on the car , digital testers can tell you the problem
Did you unhook the the old reg ?
The charging goes thru dash for the brake/generator lite

[guyatou]

Joe: I should be able to check things out this afternoon. I hope it's not a short I created under the dash when I was removing/replacing the gauges. I'll double check my wiring and report back.

Redroadster: The old regulator isn't in the car at all. The single wire from the alternator is routed directly to the white wire that runs to the ammeter.

Here's a video of what the ammeter is doing:

[guyatou]

Found the culprit: the turn signal flasher. It was going haywire apparently and causing a power fluctuation. There was even a little smoke, but that might have been the DeoxIT that I sprayed on just before the test.

I unplugged both leads to the turn signal relay and the ammeter fluctuation stopped.

Thanks to all who pitched in on the solution!

F1D4A6AB-80D1-4774-B585-2CF8FFFF7CDC.jpeg

[Gregs672000]

Run a single wire to the positive on the battery as well. Install a 30 amp fuse in the wire that goes from the alternator to the amp gauge to protect the gauge and your wiring. Keep a few just in case you blow one. With the second wire that goes to the battery installed, your gauge will not move much anymore.

[guyatou]

Thanks! The first thing I did when I installed the 60-Amp GM alternator was to add an in-line 30 amp fuse. The great big kind. The last thing I want to do is melt my original wiring harness or cause a fire!

Looks like turn signal flashers are cheap, and I found a way to put the new guts into the old can on the shiftco site. Just need to figure out which new flasher I need.

[jrusso07]

Good news!

[guyatou]

UPDATE: Apparently that's not my only problem. I bought a new flasher, installed it in the old can and plugged it into the car. When I turned on the ignition, I got arcing from inside the can, visible through the PCB. There was a small amount of smoke. It did this regardless of turn signal stalk position, or the order I connected the spades. Any thoughts? Maybe something in the turn signal switch?

[guyatou]

I’ve got 12.5 volts from green wire to white wire, and the same from green wire to ground with key in on position, engine off.

Interestingly, the first time I tested it I got 9.5 volts.

I have the steering wheel off to look for anything suspicious in the switch. It looks normal from this angle to me. The switches seem to work properly. Also, the hazard lights work fine, and the high beam switch is working just fine too.

Thoughts? I can run w/o turn signals for a bit, but that’s a great way to get hassled by the authorities ‘round these parts.

[Linda]

I believe those flashers have to ground thru the mounting screw, so maybe try sanding and spraying CNC electronic spray.
Linda

[guyatou]

Linda, I think the original grounds through the white wire -- it appears to be a ground anyway. There was a spade connector under the dash on the green wire that had the insulation worn off, and it looks like it was grounding out to the speedometer housing. Insulating that wire ended the constant-on issue with the green wire at the flasher can. Unfortunately, it's still not flashing properly. The turn signals come on after a slight delay, and they flash at a weird and inconsistent rate. And the flasher doesn't make its usual clicking noise. So, I may have cooked that new can because of the short -- good thing it was only $4. I'll pick up a new one tomorrow.