Lost dash lights 72

[Charles P.]

All my gauge lights were inoperable last night. I took a look at the small 4 amp fuse that corresponds inst lights and it appears there is still a wire in it (ie not blown). What other reasons could there be besides the fuse that would cause the loss of the dash lights? Would it be possible to kick a wire loose, bad headlight switch/rheostat etc? They were working at the start of the evening. Later on the ride home they were all off. Thanks.

[Patrick H.]

Re: Lost dash lights 72

If the headlight switch is still an original, I've got it on my 71 where there is enough wear in the rheostat/adjuster so that there are "blank spots" and my dash lights go out if I hit a bump or the switch jiggles. Try turning your light switch to make the dash lights brighter or dimmer and see if that helps. By doing this you might "hit" a spot where you can make contact and get the dash lights to work. If not, try wiggling it. If none of that helps, you probably just need a new switch. This is not an uncommon problem.

Patrick

[Joe L.]

Re: Lost dash lights 72

Patrick and Charles-----

Yes, I agree that the light switch is the most likely culprit if you're sure that the fuse is not blown. However, I'd try installing a fresh fuse "just in case". Every-now-and-then a fuse wire will appear to be intact, but the fuse is actually blown.

With the light switch rheostat, what often happens is that the "paddle" which contacts the rheostat coil becomes loose. In some cases, it might even become detached. In any event, when this occurs the switch needs to be replaced. I don't know of any practical way to repair it. Although the 68-76 switch is GM-discontinued, a perfect reproduction is available for about 50 bucks. I think that the reproduction is manufactured from the original tooling.

[Charles P.]

Re: Lost dash lights 72

Okay so that's two for the switch. The switch had been acting quirky anyway so it may be time to replace. To wit lately it is hard to put the parking lights on without the lights coming up also. Sort of hard to find that middle spot in the switch?

Refreshing my memory for dropping the dash to get the switch out. Disconnect battery, remove the seat, unscrew the steering column supports to lower column. Unscrew the dash cluster and remove. I am forgetting anything?

Also who makes the best reproduction switch?

Thanks!

[Joe L.]

Re: Lost dash lights 72

Charles-----

Your procedure sounds about right. However, you may not need to fully lower the steering column. Sometimes, just the removal of the bolts below the column at the dash (which will not, by itself, fully lower the column) will provide enough clearance for dash panel removal if you're real careful about it.

I believe that all the switches on the market have the same manufacturing origin.

[Gary Schisler]

Re: Lost dash lights 72

I replaced a headlight switch on a 73 last year and it was possible to do it without removing anything except one a/c duct. I did scratch my hand up but I got the switch out fairly easily. If you don't have large hands and know how the knob comes out, I would give it a try before you start taking things apart.

Gary

[Charles P.]

Re: Lost dash lights 72

Gary, I have a dash cluster with an intact switch on it. I'm going to pull it out of the attic and see if I can do it blindly then maybe give it a try. I'm guessing you were lying on your back with your head around the clutch pedal? If I can't then I'll go with what Joe L recommends with just loosening the column.

[Jack H.]

Note:

These Shark HL switches are both electrical and vacuum in nature. It's rather easy to drop the original switch, replace it and accidentally 'pop off' one of the vac lines when you go to re-install the switch in the cluster. Take your time and be careful with the vac lines.

Last, the HL switches have a built-in circuit breaker. It's job is to turn OFF your dash lights as a visual warning when you have an electrical fault in the tail light circuit. Some who've gone through the process of replacing their HL switch have discovered the new switch didn't 'fix' the problem with dash lights not working because they actually had a rear end electrical problem they weren't aware of...

[Charles P.]

Re: Note:

Hmm, would the circuit breaker in the switch reset itself? The reason I ask is today before I did anything I went out and purchased a box of BUSS 4A fuses. As I said the original fuse looked suspicious with a loop in the wire. I popped one in and now the dash lights are fine. So I am left with either I had a bad fuse, bad switch working intermittently, or a switch that did it's job as a circuit breaker. The old fuse I should be able to check for continuity. In any case all is well with the dash lights.

[Jack H.]

Re: Note:

Yes, given a bona fide short circuit in the car's rear lamp wiring, the HL switch's built-in circuit breaker will open/close/open and you can expect rather LONG periods of time with the dash lights out and rather short intervals where they come back on. It's a matter of heat/cooling cycles of the circuit breaker.

On recovering your lamps by replacing the fuse, that's GOOD detective work! While fuse mfgrs try to tightly control how fuses work (good/bad), it's now always that easy...

You can have a fuse whose buss wire fractures up inside the end cap area and a visual inspection won't reveal a fault. You can also have a pesky critter incident where the buss wire fractures and intermittently makes/breaks contact in sympathy to road vibration, Etc.

I wouldn't bother to try and check the old fuse. Just drive some more on your replacement fuse and if the problem goes away, you've gotten to the bottom of the situation! Pitch the old fuse, they're cheap parts anyway...