69 Dash lights won't dim

[Jon S.]

I'm stumped. The instrument panel lamps in my '69 won't dim, they stay bright all the time. I assumed it was the rheostat in the headlamp switch, and purchased a new one. After installing it, I still have the same problem. All other functions (parking lamps, head lamps, interior lights on full counterclockwise rotation of the knob) work fine (on both switches). Is there another component that has something to do with the dimmer function? It seems odd that my original switch and a new (repro or GM replacement, I believe - they're close, but not identical) would have exactly the same problem.

How about a way to test the rheostat function? I've fumbled around with an ohm meter on some of the contacts, but although I have located the panel light wire (green one, I believe), I'm just guessing on how to test it.

Thanks!
Jon #10673

[Klaus Friedrich]

Re: 69 Dash lights won't dim

Hi Jon,

the wire that goes to the gauge lamps is the gray one. There is only one connected to the light switch.

I don't know how long you own the Vette, but is it possible that the light switch was damaged and a pre-owner connected the lights to another wire to get them lighted?

Hope it helps
Klaus Friedrich
Germany

[Jon S.]

Re: 69 Dash lights won't dim

Possible, although I don't have a gray wire in the headlamp switch connector. The wiring diagrams don't show a gray wire either. There is a dark green wire on the connector that seems to control whether the gauge lights work or not. According to the wiring diagram, that dark green wire connects to the the smaller gray wires that feed the actual bulb sockets.

[John H.]

Re: 69 Dash lights won't dim

The 16-ga. dark green wire at the headlight switch is the one you're after - it goes to the fuse block, and changes to a 20-ga. gray wire at the output side of the "inst lps" fuse, which then comes back to the instrument panel and feeds ALL the illumination bulbs.