ruralandalone

The oil pressure gauge on my 86 is erratic, to say the least. It will record a normal temperature for a while, then it goes wild, like a magnetic compass would if you surrounded it with magnets. Then it settles down. Then goes wild again. Any suggestions as to what is going on?

I have a workaround that I like. I have run a new wire from the lights and am going to use a piggyback fuse to hook it in to the instrument light fuse location. with no fuse in the original socket, I bypass the problem entirely. My clock light can stay on and bright.

Thanks. This means that the splice is in the harness, where I cannot easily get at it.

No, it was useful. W/o your input I would not have figured that there was no relay. I do wish I could figure out where point "F" was in the diagram that shows where the wires from the clock, instruments, radio and cab wiring join up.

only 1 relay, and not for the lighting. That is where is SHOULD be....

My plan is to either identify and cut the supply wire nearish to the fuse box, and try to determine which side of the cut the short is on. and re-wire accordingly.

radio and clock are out. As far as can tell there is no separate clock relay in the 86. If there is, I can't find it. And I have looked hard.

I managed to get the instrument cluster out. With the instrument fuse out, the cab lighting harness disconnected, and the lights off, my power lead to the lighting shows continuity with ground. As I read it, that is definitely a short in the supply wiring somewhere between the fuse block and the instrument lights.

I rather hope not, as that means the lower instrument panel has to come off.... (:

That helps. Thank you.

By cluster, I mean the whole assembly, including the case, since I have to access the wiring.. I assume you do too. My initial attempts suggest that it is a really tight fit. It almost looks like I have to lower the entire steering column to get it out. I hope not. In other cars I have dealt with there has been enough play, or easy access to, the speedo cable. My initial looks underneath the dash don't even suggest a view of it, let alone anywhere I can get my hand in. Can you describe how is it clipped on?

I'm going to have to pull the cluster. Any tips on how to do this? How do I get the speedo cable off?

ok. No dimmer relay. One less thing to check

Since mine is an '86, it SHOULD have the relay. That would appear to be correct, in that the running lights and illumination are both controlled by the headlight switch. Different circuits, though. Whatever the problem is, it would seem to occur downstream of the instrument fuse.. If there IS no relay, then there must be a wiring short someplace. Anyone have experience with a Automotive Short and Open Finder Circuit Tester? I'm wondering if one would be useful in this situation.....

Well, the manual SAYS there is one, but as I said, I can't find it. My cab has been pretty much gutted. I don't have much in the way of working interior lights. Turn signals, running lights, headlights (high and low) headlight indicator, brake lights, running lights, glove box light all work.

I'm making progress on my 86. This week I repaced the fuel level and oil pressure senders, so all of my gauges are working. The last thing I need to fix on my project that is critical is my instrument illumination. Here is the story: When I turn on the illumination via the headlamp switch I do not get any instrument lights. The clock illumination goes out. Not dims, mind. Out. Turn off the headlight switch and it comes back on. I have voltage at the illumination fuse, and the voltage varies when I turn the headlamp switch. So the switch is good. I have power to the clock and cigarette lighter. Since gauges, radio, and lighter work, I have no indication that the grounding is poor. I do not have a working warning buzzer - though it WAS working recently. I have removed the radio, so there cannot be any issue with how I wired the radio. My best guess is that there is a problem with one of the circuits that connects to the dimmer switch. My first thought is to pull the radio/clock illumination relay, and see itfthat helps me narrow down the problem. According to my repair book, the relay is located "under l/h side of I/P, behind kick panel". The wiring diagram shows it wired to the harness at a point very close to the horn relay. I found the horn relay, but I don't see the illumination relay. Or anything that looks like one, nor do I see a socket for one. At this point I'm rather flummoxed. I CAN rewire the illumination directly, but I'd like to identify and fix the existing problem if possible. So I'm looking for suggestions as to what to try. And if anyone knows where the #&$#^$ illumination relay is, please let me know!

I removed the radio, and have a good ground. Now I'm blowing the fuse to the instument lamps.. Definitely a short somewhere. To be continued

I put the new sensor in this morning. Seems to work fine. The needle seems to periodically fluctuate, but it is certainly working - and is a great improvement. Thanks for all of the help! All I have to do now is find the short of the instrument lamps, and I'm good to go!

I LIKE healthy! Great to know. Thanks. I'll let it warm up tomorrow and see what I get, but I don't think I have a problem. Very pleased!

I got my mechanical oil pressure gauge today. I have not checked the warm engine, but I have about 55 lbs for a cold engine. If anyone can advise as to what decent numbers are, I'd appreciate it. My CORRECT sensor showed up late today, so it goes on tomorrow. Today I replaced my fuel sender and pump. I now have a working fuel gauge. I'm making progress!

yes I have, and I have variable voltage at the instrument light fuse

It will take me a couple of days to get 'er done, but I will do that.

Well, I would not say "hacked', exactly, but yes. I do not think I used anything but power and ground leads, though.

Thanks for the link. At this point I REALLY doubt it is a ground issue, but I will certainly double check asap and report back

I think the clock is fine, and the ground, as tested at the cigarette lighter, seems good. Fuses are good too. I have appropriate (variable) power on the downstream side of the instrument lamp fuse, and no lights.