Hi I am new to this site but definitely not new to owning Cutlasses I have had this one since 93 right after I got out of High School and had 2 more prior to that one. My son and I just got through putting the 78 back together after sitting for a few years. We put in a rebuilt 350 out of a 69 in it and runs like a top, the problem is none of the gauges work now (this car has gauge cluster and round speedo not real common in these cars) and the alternator wont charge until you rev it up to about 2500-3000 rpm. The fasten belts and brake warning lights come on at start up. Sometimes the oil pressure gauge will work but thats it(also after you rev it but not all the time) also the blower fan it is not working either. Any ideas to what might be wrong. This is the third engine I have had in this car so I am pretty sure I have all the wiring ok under the hood although it has been with out an engine in it for a few years so I might of missed something but I doubt it.
All interior gauges wont work
- Thread starter Wade
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Start with something that has the original sending unit, or doesn't need one. Like the gas tank or speedo - are these working properly? Focus your effort there before moving to something which could be a sending unit problem
If all of them don't work it sounds like you could have a bad ground. Run a quick temporary wire directly from the neg. terminal to your ground post you're using and see if they perform any better
If all of them don't work it sounds like you could have a bad ground. Run a quick temporary wire directly from the neg. terminal to your ground post you're using and see if they perform any better
None of them work was kind of thinking ground as well or maybe power is not getting there. The fuel gauge shows past full like they do when the wires break, it was working when parked but that doesn't mean its not broken now. The oil pressure gauge does the same until you rev it up enough for the alternator to kick in then it works for the most part but still acts up occasionally. I have only put about twenty miles on it since got it running though. All the gauges and the dash lights ground through the circuit panel on the back of the gauge cluster don't they? I suppose there could be a break in that. Any idea which wire grounds it or where to run a secondary ground wire to it? I haven't torn the dash apart as of yet but looks like that might be my next move.
Wade said:
I'm not sure, I didn't work with my stock gauges, just threw em out. try following the black ground wire/s from the gauge panel. Buy a bunch of wire from the auto part store and just wire it directly from the neg. around the outside of the doors and splice into your ground if you can't find the post...just temporarily & quickly. Then use a test light or multimeter to check the hot wires with the ground you just put in. You should be able to find the problem that way without too much dash disassembly
Hey Partner,
Just a thought but it doesn't sound like ALL your gauges are going bad at once. If I was a betting man, your alternator is causing havoc on your system. Is it a 10si or 12si? Is it a 1 wire or 3 wire. It sounds like it's acting like a 1 wire but most 5th gen cars have 3 wires. If you have to rev it for stuff to happen then that Alt. is not working properly. Probably putting some goofy voltage through the system due to a bad regulator. I rebuilt a spare last year with a $35.oo kit just to see if I could do it and that thing worked great.
Just a thought but it doesn't sound like ALL your gauges are going bad at once. If I was a betting man, your alternator is causing havoc on your system. Is it a 10si or 12si? Is it a 1 wire or 3 wire. It sounds like it's acting like a 1 wire but most 5th gen cars have 3 wires. If you have to rev it for stuff to happen then that Alt. is not working properly. Probably putting some goofy voltage through the system due to a bad regulator. I rebuilt a spare last year with a $35.oo kit just to see if I could do it and that thing worked great.
Also check the circuit board on back of the cluster, the plastic tends to separate, exposing moisture to the copper traces, then they corrode and break, leaving you with a nonfunctional cluster.
You may be able to get one from one of the non-gauge-equipped Cutlasses, I'm not sure exactly how the clusters are laid out. I know with the Malibu/Elky/Monte clusters, the later ones that have dummy lights in place of the gauges have interchangeable boards.
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