1974 Cadillac Electrical Stuff

[bitchofanubis]

Since you all were so helpful about my insurance question, I'm hoping someone might have some knowledge about my latest dillema.

In the dash of my hearse, only a handful of the lights work. There is a long row of indicator lights across the top of the dash, two of those work. The blinker indicators work, those are right next to the speedometer, but there is no backlighting for the speedometer at all. It's really freaky driving when it's dark out, I can't see anything in the dash, can't see how fast I'm going, etc.

The mechanics who fixed the hearse, and got it to pass inspection, said they would refer me to a Cadillac specialist rather than run up my tab trying to figure it out. Should I go to a specialist? Is this something I can conceivably work on myself? I have a 1974 shop manual with a fold-out wiring diagram, but it looks pretty darn complicated.

Thanks!

[hotroddwayne]

Well first check the fuse panel & make sure the fuse labeled "instr lights" or "instr panel" is good. Even if it's good, clean the contacts up to insure a good connection. If that doesn't fix it then you'll probably have to take loose & pull out the instrument panel some. I think you'll have twist-in bulbs (on an early attempt of a printed circutboard) but can't say for sure. Twist-in bulb housings are typically a 194 bulb so check the bulbs and also the electrical plug-in to the speedometer panel. If that doesn't cure it... break out the voltage meter & start tracing 12VDC power from the fuse block up to the dash panel.

[kaptinkaos]

When I bought my 76, none of the backlights worked on the dash, it turned out that all the bulbs were burned out. I had a mechanic disassemble the dash since at that time I wasn't sure on how to do it.
In my truck which also had no lights, it was the sockets, they were corroded, cleaned them, it works okay, sometimes my dash lights work, sometimes they don't.

[bitchofanubis]

Thanks! I think the mechanic may have done some of that already, but I'd sure hate to pay a Cadillac specialist to replace some bulbs, I know I can do that!

[bitchofanubis]

I'll have a peek at the body manual and see if I can figure it out, thanks!

[Morella]

I'm not sure about anything before 1976, but I do know that pulling the dash on a 76 or newer can be dangerous. You have to pull the A/C vents out to get some of the dash screws, and they break easily if you don't know how to do it, or the plastic is brittle.

If some of the lights work, it is probably not a fuse. Either some of the bulbs are burnt out, or the contacts have corroded. This is common with all cars that have PCB and twist-in bulb sockets. I had to pull the entire dash out of mine when I got it, because the Climatron control wouldn't even move, and I had dust behind the light lenses. That was quite a job, but since I tow bar'd it home, it wasn't a problem getting it there. Funny...I got better gas mileage towing it with a 92 Chevy pickup than it gets by itself. The 76 has a crappy cam, and I wish I had the energy to replace it.

BTW, if your alternator warning light goes out, your alternator won't put out, unless you flash the brown field wire to +12v, or use a resistor between it and a switched circuit. I was not about to pull my dash out again, so my "low washer fluid" light is now my alternator warning light.

-denise

[bitchofanubis]

Great information! Thanks!