Voltage is all over the place!?

[Pull-N-TugTX]

My voltage needle bounces all over the dash until I get up to 21-22hund on the tach. Then it sits on the high side. At idle with the lights on I have alot of flicker and dimming. New batteries, alt, starter, solenoid. Any ideas where I should start? Electrical is not my strong side, friend suggested maybe a glow plug short?

92 7.3 idi 360k 5spd swb F350

[Pull-N-TugTX]

Anybody??

[BadF250Boy99]

my trucks voltage guage bounces around all over the place right after start up
i believe thats caused by the glow plug relay engaging trying to get the truck running

[jesilvas]

Ya know, my lights dim and brighten even at normal RPMs, and at idle you can even hear the motor almost being bogged down in tempo with the lights, like when the AC compressor engages. I think it's the alternator voltage regulator going on and off, causing the alternator to create electricity, and then not, rapidly. Why the VR is doing that, idk. Either the PCM is commanding it to or it's bad. If the PCM is, one condition for the alternator not producing power per the PCM is GPs being engaged. Maybe the GPR is constantly being cycled too?

[BadF250Boy99]

i know with my truck ive popped the hood and heard clicking coming from the glow plug relay 94 idi turbo

this causes my lights to flicker and the guage to bounce


there was a cheap idea a guy on youtube posted using a water heater thermostat to a switch, once the engine bay temp reached 100 degrees it would disable the glowplugs when starting so it would reduce the wear

[ianstew]

I would suspect voltage regulator in the alternator.

[Ol' Smoky]

Id say to put a voltmeter on the batteries and see in numbers exactly what the alternator is putting out, but it sounds very much like a voltage regulator. Is it internal or external regulator?