The Stovebolt Site Forums The Shop Area The Electrical Bay TF Light Switch Mounting Question

My dome light doesn't work, and I've isolated the problem to either a bad ground going through the main light switch, or that the rheostat fails to engage ground when turned full left (full bright on the dash dimmer.)

How do I remove the light switch from the dash? (The shop manual has no detail on this subject, only wiring diagrams.) It is extremely tight against the dash wall.

Any recommendations on how to verify the rheostat works properly? No problems with the dimmer, only switching to ground.

Bill

Hy TxLaTx, you might want to disconnect the battery before you try this. Pull the knob on the switch all the way out (headlights on position), now reach under the dash, on the bottom side of the switch (opposite of the wires) there should be a sping loaded button, push in on the button and hold it, now continue to pull on the light switch knob, it should come right out in your hand. Once the shaft is out remove the bezel nut with a slotted screwdriver, and the switch should be free of the dashboard, once you remove the wires you can take the switch to test it. Before you do all that look under there and make sure all the wires are connected to the switch, hope that helps.

it's possible the tab on the rheostat 'rotor' isn't making good contact to that terminal [bent or burnt], but if the dash lights work I'd suspect other problems - assuming you've found the wires where they come out of the A pillar to the switch, take the ground wire off the switch and touch it to ground - if it works, then carry on to the switch, if the light doesn't work then one of the wires to the light is bad or you have the hot wire on the wrong terminal

Bill

3B - Thanks for the instructions. I think I understand how it works and will use them when I get to that point.

Bill - Thanks for weighing in. I'm 100% sure that the wires that come out of the A pillar have continuity to the socket, proven with my multi-tester. I pulled the ground wire off of the switch and grounded it to the frame, and the dome light (with the dome wire still connected to the switch) comes on. So at this point, I think I've traced the problem to in or at the switch, namely a failure of the ground lug to reach ground.

Your comment about the rotor not making good contact at the switch terminal strikes a chord. To me, the switch feels sort of "mushy" once it goes beyond the detent at the full bright position. There isn't anything like a click or snap when I reach dome on, just more like gliding through a marshmallow after reaching full bright.

If I check for continuity between the dome lug (power) and the ground lug when the rotor is full left, am I proving anything? It seems to me that this would isolate the problem entirely within the switch and that the cause is the rotor not making contact.

I see reproduction switches aren't too expensive (~$35.00) but I'm sure they're Chinese. Can anyone comment on the quality of the reproductions?

Bill

yes you should get a reading between the power terminal and the ground terminal - the repro switches originate from Danchuk, they're the same as the tri5 cars and he originally reproduced them, although they might have since been farmed out offshore - I have one and it's been fine, check your NAPA and see if they list them

Bill

Great information. I'll post a follow-up!

Bill

Update:

I bought a new switch from American Classic Parts, the Stovebolt sponsor, and I'm happy to report that the switch they offer is Made In USA! If that doesn't lure you to buy from them, their price will.

I replaced the old one using 3B's instructions, and now all lights work as designed.

I probably spent 10x as much time chasing down the problem than it took to simply replace the switch.

If anyone needs to do some night reading, stop by my truck. The dome light works wonderfully. Thanks to Bill and 3B for the help.

Bill

Hy TxLaTx, I'm glad it all worked out.