Weird Electrical Issue

[jasonw3]

I have an ongoing electrical issue on my '98. It's stock apart from an upgraded alternator and LED lights. At night at idle, the gauge lights dim when the blinker is on at stoplight. I can make the battery light come on if I hold down the window "up" buttons on multiple windows. However, if I keep doing it for 20-30 seconds, all of a sudden there's adequate electrical power and no issue.

The same happens when I park the car. When the engine is running at idle and brake is pressed, the LED headlights weaken and sometimes flicker, as if there's not enough voltage. I can make it weaker if I press the window switches. If I turn the ignition off, it continues acting that way for about 15 seconds, and the all of a sudden the lights get bright like normal and there's no sign of weakness.

I originally thought it was the battery, so I replaced it. I've also replaced and upgraded the alternator, returned it, and put a second replacement on. No change.

It's almost as if there's some switch somewhere that "clicks", but since it occurs both when the car is running and when on battery power, I'm less inclined to think it's an alternator or voltage regulator. Any ideas?

 

[AuSeeker]

Maybe a sticking/bad relay?

 

[fourwd1]

I'd start by checking all the battery/alt related cables for loose/corroded connections.
Alt to batt pos, batt pos to elsewhere, batt neg to grounds (fender, frame, block), etc.

I'd also be monitoring battery voltage under all the conditions you describe (bulbs 'dim' or normal, engine off or running, etc.) A written list of the results might be handy.

A good batt w/engine off (no load) is typically 12.6V, w/engine running (no load) at least 13.8V to properly charge that batt.
These are 'typical' voltages, YMMV.

If you can determine all those basics are good or bad, it should help point you in another troubleshooting direction.

 

[phattyduck]

I would start with making sure that every lighting circuit has at least one incandescent on it (interior lights, parking, brake, turn both sides). That will get a baseline for you there.

I had a weird one years ago where the reverse lights would come on with turn signals (or something like that) - it turned out that the gauge cluster flex circuit went bad (missing ground somewhere) that linked some things that otherwise shouldn't have been... so there's something to think about if you can't find another cause.

Definitely get a multimeter on the battery voltage to see if it is an alternator issue.

I would also check grounds (both sides in the rear near the tail lights, engine bay in a few places on the inner fenders, I think there are grounds in the driver and passenger footwells, etc.

-Charlie