1985 GS 12A 78K on the clock, Normally carried 60+ pounds oil press. suddenly it dropped to @40 pounds. tried 20/50 oil ,no help. My volt meter quit, and the heat sensor quit. How lucky can I get. At this point I am out of altitude ,airspeed and ideas. What next.?

 

Check you alternator.

 

^ agreed

sounds to me like you arent gettin any or gettin very little power to your gauges...alternator is usually the case

 

My car suddenly did that a couple months ago. The oil pressure went to exactly 40psi for some reason. I had just changed the oil cooler and I think something got caught in the filter that was causing a restriction.. I changed coolers (after flushing the new one) and oil and it fixed the problem..
Sounds like you got an electrical problem, though. You may also want to check the harness connection for those gauges if it`s not the alternator. It is located on the passenger side near the emissions stuff and I think it goes into the firewall also.. 8 wire connector IIRC.

 

When the alternator goes out, ALL the idiot lights come on and stay on.

May be the gauge fuse or the fusebox prongs. Check the fuse blades for green corrosion from the prongs. There is also a voltage regulator for the gauges that could go bad, but it's never happened to me.

Do your turn signals work?

B

 

turn signals work,only the volt meter and theoil press are screwing up .Have a new heat sensor to install. drop in oil pressure worries me most. the volt meter sometimes works and then don't. Darn cars anyway!!!!!!!! Bob

 

Bob,
Install a mechanical oil pressure gauge. if you still curious about the stock gauge, I suggest to take the sender apart and clean it. Now for volt meter, IIRC, there are 2 wires: 1 connects in back of the alternator and the other is in the starter solenoid.

Wish you were closer. I will fix that for free...well not quite, it will cost ya a 12pack of heine

 

Since turn signals work it is NOT the fuse I suggested.

B