70sgeek

Fuel gauge has recently stopped working, but not sure if a ground or wiring short issue. Gauge itself won't move.


Generator lamp won't light if the parking brake light isn't plugged in but the generator light stays lit with the engine running - dimly if the parking brake isn't set, bright when the brake is set.


On the harness plug, the dark brown and the black wires are live with key on. None of the others are powered with the key on.


under the dash, a black wire which is plugged into a capacitor wire is fully live (key on or off) - not even sure what that capacitor is for (mounted off to the right of the steering column) but I doubt it's supposed to be live.


The background cluster lamps all light up properly with the headlights on and attaching another ground from cluster to (-) battery didn't change anything as to the gauge or warning lamps.


If I plug a lamp into the seat belt warning socket, the dash buzzes but lamp doesn't light.


To date before all of this, I installed a new engine harness, horn relay and rebuilt tilt column (which has new t/signal harness and column switches). Also installed a new radio, which utilized existing wiring plugs under the dash which weren't being used (original radio power, clock power lead for the amp). Also added under dash analog gauges, using clock lighting lead to power the back lights and existing connectors to power the gauges.


Oil pressure gauge is plugged into the ignition post on fuse box, volt gauge plugged into a space above a switched fuse (radio) for now.


The radio grounds are all bolted to the bare metal dash underside, the gauges to steering column mounting bolt.

Any thoughts on what I should be looking for as a possible cause for these issues?

oldcutlass

Check to see if you have 12v at the gauge. The capacitor you mentioned sounds like a signal stat. Make sure you have the correct connections at the voltage regulator and the alternator.

70sgeek

I replaced the voltage regulator as well with a brand new AC Delco unit and new capacitor for that as well. Alternator is new from a few months back and there were no issues with that up to this point (no changes made to its connections),


I question why the pink lead on the gauge harness connector isn't powered and the black lead next to it is... Not sure that's how it should be but I'll be studying the schematic a bit tonight to see what I can decipher


good suggestion to check actual voltage, I am curious to see that that will read through these live connections Just not sure the ones that are live should be....

70sgeek

weirdness seems to be resolved


seems I had a multitude of issues with the fuel gauge pod - changed the fuse (which still looked ok) and that brought the fuel gauge back. Changed the circuit board and that brought some of the lamps back. Changed some of the bulb sockets and that brought the rest of the warning lamps back...


so in short (no pun intended), appears I needed a new fuse AND essentially most of another fuel gauge cluster...


I'm sure I probably fried that under-dash .5mf capacitor when the black lead going to it was powered, because when I changed the fuse, the black lead wasn't powered any more (which I figured it shouldn't have been in the first place). It probably doesn't do anything important but I'll replace it anyway, just in case.


Hoping all else solved at this point - dash harness looks good physically so hopefully no replacement necessity in my immediate future...

oldcutlass

Glad you figured it out.

Fun71

You can check to see if the capacitor is shorted (leaky) with a multimeter. Use the resistance range and see if the resistance starts low and then increases to an open circuit (very high resistance). If the cap is shorted or really leaky, the resistance will not increase.