67 Instrument light circuit

[1carlover]

Help!! I'm still trying to isolate the cause of the dash light fuse blowing in my 67 r/t but can't find the source of the problem. More than likely its a grounding issue from an undetermined source and the dash lights are the only thing affected. The headlight switch and wiring or circuit board are not the cause. The other circuits and accessories work as they should and even the dash lights have occasionally worked without the fuse blowing. I don't know where else to look and need some fresh ideas.

 

[Don Frelier]

The headlight switch and wiring or circuit board are not the cause.

Besides the bulb inserts in the gauge cluster these are the only three things in the circuit.You could try a slow blow fuse? (2 seconds longer is'nt going to damage anything)

 

[R413]

Where the clock or the block off goes there is a wire and socket for the bulb From the fuse box. There is also a separate wire to the radio lamp. Look at those 2 also.

the feed is from the headlight switch to the fuse box. Remove that feed wire from the headlamp switch and operate the car an see of the fuse still blows.

do you have anything tapped into that circuit for aftermarket gauges/tach, radio, etc.

 

[1carlover]

Nothing is tapped into the instrument circuit. Headlight switch goes on and off no issues. Problem occurs when dash light switch is turIned to the full left position. I dont think there is a radio lamp wire.

 

[R413]

So if you turn the dash light dimmer to the middle area to dim them a bit will the dash lights stay on without blowing the fuse? Then it points to the headlamp switch.

 

[1carlover]

It's not the headlight switch as I've tried several. On several occasions the dash lights will work perfectly then without notice will stop working the next day, blowing the fuse and the dome light goes out as well.

 

[Billccm]

Get a incandescent test lamp and clip across the blowing fuse location. It will light bright indication of a short.
Now unplug various branches until the light dims or goes out. That branch will have your short.

 

[1carlover]

The dome light circuit also gets power off the instrument fuse. When the fuse blows the dome light goes off but that's all. Each time I replace the fuse I make sure to turn off the dashlight dimmer first. Are you saying that I should jump the fuse with a test light then disconnect one circuit at a time at the back of the fuse block or pull one fuse at a time to check. By the way, Thank you for taking the time to help.

 

[Billccm]

The test light goes across the fuse contacts. It is now your visual fuse. Glowing bright is a short. Remove the dome light bulb.
I like to unplug at the harness connector. Start at the instrument panel connector, then work backwards.

 

[1carlover]

I have a 12v circuit tester and a multimeter but not sure what instrument you are using.