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

[Dave_Darling]

The master cylinder switch is supposed to flash the brake warning light when it detects a pressure imbalance between front and rear brake circuits. Like what happens when a brake line fails catastrophically (almost unheard of with stock lines), or when you boil your brake fluid (rare), or when you bleed your brakes (relatively common). Most of these switches require you to reset them to turn off the light.

You reset them by pressing the button on the switch, which is covered by a rubber cover. Just press the cover in to press the reset button.

--DD