Interesting Electrical/Charging Issue Options

[GregAmy]

1974 2L 914. "Driver" condition, way far from concourse, but drives well. I've noticed from the beginning a relay clicking under the dash; at first I thought I left my turn signal on, but it's not. It didn't seem to bother anything so I ignored it.

Couple nights ago I drove it for the first time at night. It was then I noticed the "gen" light was glowing very faintly, and at idle I'd hear the click and the light would get brigth(er), then slowly dim. Then it would click again, get bright(er), then dim.

I've also noticed from the beginning that the voltmeter would show 13+ volts normally, except when I stepped on the brake; when I did that it would go below 12. Same thing happened when I flipped on the lights. Strangely, when I did either, the clicking would stop...

Today I did some basic troubleshooting. Had my assistant sit in the car and I measured voltage directly at the battery. At idle, center console gauge shows ~13v, VOM showed 13.75. Good. Asked Vanna to step on the brakes; gauge showed ~11.8V, battery showed 13.4. Asked her to turn on headlights and stay on brake; center voltmeter showed ~11.5, battery had 12.3-12.5. Asked her to rev it, battery voltage got up to ~12.7.

So it really doesn't sound like I have a charging issue, it sounds like there's something going on under the dash.

I'm gonna guess you're gonna tell me it's a ground under the dash. But can you offer where I might find that? Or where I can run one to supplement it? The battery (from a Miata) has been moved to the rear trunk; it's positive cable goes directly to the starter and its ground to the ground stud under the rear trunk. The ground strap from that stud to the transaxle is very good, I've removed, cleaned, and re-attached it.

Car seems to be running fine, starts, drives, charges. I'm just looking to get accurate readings from the gauge and to stop that clicking...

Thanks!

Greg

[GregAmy]

I love me a good electrical mystery...

So read up there ^^^ on my questions about charging. "TL;DR" is that my battery is charging fine, but the gauge in the center console is wrong. Fine, no prob, I'll get around to adding a dedicated wire from the center console to the starter/battery to give me a good reading. But that dim/flickering generator light and the relay clicking caught my attention...

I printed out the full wiring diagram and started looking. It made no sense, that I had some relay clicking under there in time with the gen light. Couldn't figure it out (foreshadowing: still haven't) but I started looking around on what could cause that and noticed the flasher relay is using the same power circuit...a clue.

I got home tonight and pulled down the fuse/relay panel and looked around, all seemed well. Ground from there to the chassis was strong, no corrosion and 0 ohms resistance to other points on the chassis. Fired up the car and noticed the gen light flickering once every second or so, along with a click. Basic tactile search revealed it was the flasher relay.

Pulled the relay...and no more clicking (of course) and no more gen light flickering. Plugged it back in and noticed the relay was buzzing along with the occasional click. Replaced the flasher relay with a spare and the relay and it started clicking at the same tempo as the turn signals -- and the gen light flickered as if it were a turn signal indicator.

Final clue: I tried the turn signals, and the T/S indicator flickers in time with the signals (which seem to work fine all corners) but then stops lighting up after 3-5 times.

Something really strange is going on here. Since the gen light works fine with the T/S relay removed, I'm guessing it's something in the turn signals/emergency circuit that's no right. Bad ground, swapped wires, something that would cause the relay to flicker on and off and cause the gen light to illuminate. The gen light works off of differential voltage, so I'm wondering if the supply amperage to that circuit is insufficient? all of it is fed through the 15 keyed circuit; bad ignition switch? Or maybe the turn signal circuit has some oddball ground that is sucking up the amperage?

Remember: turn signal flasher removed, gen light works fine. Slip it back in, relay buzzes and/or click along with the gen light. Go.

All the makings of a good murder mystery. But given I have a lot of other things to deal with in my life, if you've solved this before please toss the answer at me...

Greg