Instrument lights blown fuse

[David H.]

Looking for some suggestions of where to start.
Have installed all my fuses and one fuse, the instrument lamps fuse
blows out as soon as I touch it to the contacts.
Putting a meter across the fuse contacts allows all the lights to function.
I think it may be the light switch but any suggestions will be gladly considered.

Thanks

[Edward J.]

Re: Instrument lights blown fuse

Dave this may require a close inspection of each on the light sockets there maybe a bare wire shorting to one of the sockets( most of the time right at the socket itself), or a frayed protective coating which if grounded will blow the fuse instantly. If you have been under the dash recently and moved some wiring or wires, be sure to check that area. and the same goes for if you have installed anything electrical lately. ( Radio, Clock etc.)

GM generally uses a gray power wire to feed the dash lamp circut , just look for those colored wires. Good luck Ed

[Domenic T.]

Re: Instrument lights blown fuse

David,
I remember that on passenger cars the tail lights and instrument lights were on the same circuit. That way the driver was aware that he was driving without tail lights.

Are your tail lights working?

As I remember all GM cars would mix the 2 circuits.

DOM

[Alan D.]

Re: Instrument lights blown fuse

Dave "Putting a meter across the fuse contacts allows all the lights to function."

Are you attempting to measure the current with the meter?? If not do not understand how the lights work.
What type of current are you measuring with meter? Is the fuse large enough for the current specified in the book?

[David H.]

Re: Instrument lights blown fuse

I am installing a brand new wiring harness after a body off restoration. I am in the process of putting things back together. I have installed all the instrumentation and all gauges work properly. Headlights work, tail lights work. I believe the tail lights are on a seperate fuse if I remember correctly.
I put the probes of an ohm meter across the fuse connector contacts for the instrument lights. The lights all came on correctly.
The ST-12 calls for a 3 amp fuse for these lights, which is what I had in it. I am going to measure amps at the fuse connection tonight to see what the amps are there.
Am I missing any amperage reducers under the dash? I have the one that is at the amp gauge.

[Edward J.]

Re: Instrument lights blown fuse

Dave, I am not a C1 expert but I do not believe that there are any other reducers, The ballast on the headlamp switch is a voltage reducer so to speak.

I think you have the right idea to measure the amp.s to see what the draw may be. I wonder if the replacement bulbs sold today draw more current than
the OEM ones do?( you know the China crap) being that 3 amps is not a lot.maybe a 4 or 5 amp fuse. would be more along the lines.

[David H.]

Re: Instrument lights blown fuse

Tested all amps at the fuse box, lamp sockets etc. and all seemed correct.
Swapped out the light switch and the lights seem to work perfectly.
Thanks for all the suggestions and help.

[Jeff P.]

Re: Instrument lights blown fuse

Start taking out all the bulbs, check wire diagram to to whats on this circuit good luck