Need help to trouble shoot dash light on a 1970 GTX

I need simple ways to trouble shoot the dash lights on my GTX. How difficult is it to remove the dimmer switch for the dash lights? ALso, The dome light does work on the interior when I turn the dimmer switch.

I found when that happened to me, the spring that varies the voltage was gone.
Do the dash lights come on with the dome light?

Hi Andrewh just the done

You can jumper across the wires going to the rheostat (coiled wire) and if the dash lights come on you know it's the rheostat. make sure the light switch is on

Sometimes cleaning the contact will help but not always

Is there any chance you can give me step by step instructions? And do I have to take the switch out? How hard is it to take the switch out? Thanks.

The dimmer switch will have two screws on the back. One on one of the upper corners and one on the opposite lower corner. The switch is fastened to the plastic dash panel that surrounds it. You can get to it with a stubby Phillips head screw driver, but if you have air-conditioning you have to remove the duct first. Even then it's going to be a bit of a pinch And easier to reach with the drivers seat out of the car, but it just depends on how flexible you are. Once you get it outthe dash there should be enough wire attached for you to pull it down below the dash and work on it.

If the switch is bad, which a lot of them do, I recommend Jim at J.S. Restorations. He's a member here and he does fantastic work.

I personally think you'd have to pull the dash to get the dimmer switch out....it's freaking tight up in there. You might be able to get the plug off the back of the dimmer switch, check a wiring diagram & jump the wires to bypass the rheostat (dimmer) like TJP suggested.

You might want to double check the 3 amp fuse too which is on the far right of your fuse block. That runs the dash lights.

Another vote for Jim at J.S. He just did my E-body dimmer switch, and it works great. Two week turnaround for mine.

OK.... Here U go..
Pull the connector off the Dimmer Control, there are (3) female 0.25" tab terminals:
1. Make a short 4" jumper wire (18 guage) lead with (2) male 0.25" tab terminals
2. On the connector U just unplugged, insert the jumper lead to the center terminal (Tan wire) and upper terminal (Black wire). Note the Black wire comes off the Headlite switch with 12V+ and the Tan wire goes to the dash instrument lamps. What this does is to simply bypass the dimming rheostadt so now the lites get the full 12V+.
3. Next make another short 4" jumper(18 guage) wire with (1) female 0.25" tab terminals and (1) male 0.25" tab terminal, connect 1 male end to the open female terminal in the connector. And connect the other female end to the bottom terminal on the dimmer control, note that this is grounded when the rheostadt is fully rotated to turn ON/OFF the Dome lite.

Now the dash lites get a full 12V and U haven't cut any wires so U can return everything back to OE specs if U ever get a new dimming control. I hope that helps.

Just my $0.02...

This sounds like great advise. I would double check to make sure the dash lights get 12V and not 5V, but otherwise Sinitro sounds dead on correct.