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Discussion Starter · #1 ·
Looked thru the search on my subject and found some terrific info, but need a bit more.

I am putting back together my 69 convertible and have put off doing the dash due to extreme anxiety of failure. Well, things were going pretty well and as I was putting the instrument panel back into the dash I checked my lighting one last time and my instrument lights would not light up - no power to the sockets per my circuit checker. Headlights work, hi beam indicator works, gen light works, under dash courtesy lights work, and cigar lighter works. I have installed an older light switch and when the inst. lights were working they would flicker as I turned the rheostat. Also, I did notice that only my pass. side door jamb switch works properly and my drivers side switch does not turn on the courtesy lights when the door is open. I have checked fuses and all appear unbroken. I intend to clean up contacts and R/R all fuses tonight and check for power to each side of the fuse. I believe I have all grounding straps connected for the instrument panel.

Any other suggestions?

Thanks,
Sam
 

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Discussion Starter · #2 ·
Also, my clock works. I have not installed any rear lights or front lights other than the headlights. Horns are not installed either.

Sam
 

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Might try popping in the rear lights and see if they work before you look further. That bit of information would be useful.
 

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Could be a bad rheostat in the head light switch but the tail light circuit is what powers the dash lamps. Just seeing if that works OK before moving down further.
 

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Discussion Starter · #6 ·
Connected the tail light circuit (incl. the gas tank sending unit). The 2 side marker light bulbs which were installed in their sockets illuminated as well and the fuel gauge works too. I did notice while taking some bags with various fasteners in them off of the flat wire harness (the portion which goes under the carpet) that the bag and a small portion of the flat harnes covering were melted together. Aha, a short I thot, but the wires within the harness are fine and intact. I think there was a short betw the harness and the bag of fasteners that generated heat but not enuff to harm the wires w/i the flat harness. I R/R all fuses with new ones. Another observation, I hear a click every 45 secs or so when the battery is hooked up and the fuses are all installed.

What are your thots now?

Sam
 

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Discussion Starter · #7 ·
I tried two other spare Chevy light switches (old ones) to see if the rheostat may be the culprit. i grounded the switch and connected the the light harness plug to the switches. Although both turned the head lites on/off, neither would turn on the instrument lites. Though, neither of these spare switches would turn on the courtesy lamps(2) like my original light switch will.

I have hooked up the brake idiot lite and the generator idiot lite and they both turn on when the key is turned to the 'on' position. Are the oil and temp idiot lites also suppose to illuminate with the key in this position?

Thanks,
Sam
 

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Oil light, yes. Temp light only when you turn thr key just a little bit further towards the START position.
See if you have 12 volts to ground on both sides of the dash lamp fuse.
 

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Discussion Starter · #9 ·
John,

The only time I get 12 volts (12.6 actual) is on the right side of the Instrument Lamp fuse when I pull the light switch out to the parking lite or headlite position. With the light switch pushed in there is no measurable voltage on either side of the Inst Lamp fuse. With the lite switch pulled out I noticed if I rotated the rheostat that I either got 12.6 volts or 1 volt - nothing inbetween. I noticed too that I had to rotate the rheostat nearly all of the way to the right before it dropped to 1 volt.

I checked for voltage on all of the other fuses and got this:

The three 20 A fuses on the left side of the fuse box (above the Inst Lamp fuse) ALWAYS have 12 volts to ground on both sides of the fuses.

The five fuses on the right side of the fuse box have 12 volts to ground on both sides only when the key is turned to the "ON" position.

Sam
 

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Sounds like the rheostat is either worn or real dirty. The dash lights sound like they are coming on bright and then going off.
 

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Discussion Starter · #13 ·
For John: No, my dash lights (instrument lights) are NOT coming on. That is a measurement at the right side of the instrument lamps fuse.

For Dean: Yes, I am getting a voltage measurement ONLY on the right side of the instrument lamps fuse.

Sam
 

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Originally posted by Dean:
I do ? :confused:
Well I do know if you have voltage on one side of a fuse and not on the other, either the fuse is blown or the fuse holder is not making contact with the fuse - Right?
Sure you do. You've been doing this stuff longer than I have.
 

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Discussion Starter · #17 ·
I have a 4A fuse (new) in this socket (short one). Could I bridge the gap betw the two terminals to see if I can get the inst lights to work?

Sam
 

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If you see voltage on one side of the fuse clips and not on the other, bridging won't help. That's because the clips are dirty. Bridging across dirty clips won't make a good connection and probably won't work. Try cleaning the clips where the fuse fits in.
 

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Discussion Starter · #19 ·
John,

Does it make sense that I only get a voltage on the Inst Lamp fuse WHEN THE LIGHT SWITCH IS TURNED ON? This is different from how the other fuses work i.e.

"The three 20 A fuses on the left side of the fuse box (above the Inst Lamp fuse) ALWAYS have 12 volts to ground on both sides of the fuses.

The five fuses on the right side of the fuse box have 12 volts to ground on both sides only when the key is turned to the "ON" position."

Under normal operations can you turn the inst. lights on w/o the key in the ignition?

Sam
 

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It all makes sense. The left fuses are hot without the key. They provide power to things like hazards, cigarette lighter, dome light, etc. Things that can run without the key.
The right fuses are only powered with the key turned to RUN or ACC.
The INST or dash lamp fuse only has power on it after you pull the head light switch.
Yes, the outside running lights and the dash lights will come on without a key.
 
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