Intermittent operation of the running lights ('67 Monaco)


Well-Known Member
Aug 21, 2022
Reaction score
Ontario, Canada
My 90 YO dad is visiting tommorrow (he doesn't come my way that often) and I thought it would be a good time to take the Monaco out of storage so he can see the car he bought for the first time in probably 20 years. I'll even try to get him to drive it (he still has his license).

So I'm driving it home, it's just turning dark so I put the lights on, everything is working (but the dash lights are too dim for my taste...). The amp meter is fine, it's charging a little, headlights are on, brake / turn signals all work and are bright. Wife is tailing me, she says all lights are working.

I get home, turn the engine off, talk to a neighbor for a few minutes, and then I flick the switch to running lights because I want to see those big tail lights in the dark. But nothing comes on! I flick it to head lights, they come on, but running lights are not on. So I'm cheesed about that. Talk to my neighbor for another 10 minutes, I try it again, this time the running lights come on (I love those lights!) So I'm not sure where to start with this. Are these toggle light switches known to be finicky?
I would not suspect a toggle-switch switch would be any more finicky than a rotating or pull-on switch . . . as they are all what I'd term "sliding contacts". Just a different method of making the contacts slide onto and across each other.

Might just need to move the lever on the switch several times to wipe any accumulated stuff off of them for more consistent operation?

When the tail lights did not work, did the brake lights?

Just some thoughts,
I had / have some electrical issues that I see now. It's been almost a year since I've had the car out, and before that it was 20 years. One was that the voltage regulator (must be mechanical type, it has wire-wound resistors on the bottom side) was not working properly. I had run a separate ground wire from the battery to one of the mounting screws in the past. I had a replacement one in my parts stash, probably electronic (no wire-wound resistors) and now I get proper voltage at the battery when the engine is running.

I have unplugged / replugged the 3 connectors at the bulkhead, one wire was either close to being broken or did break when I did that, but I fashioned a repair. (now that I think about it, it might have been an alternator wire that was broken and hence the regulator didn't need to be replaced...)

Right now, the running lights work, and the emergency flasher works (it flashes the running lights, front and back). I'm not getting brake lights right now (turn or brake lights not working, front or back). The car interior lights and radio are working, windows are working, so there is power getting inside the cabin of the car, engine starts and runs, amp meter works.

I have the service manual PDF file, but following the wiring diagram is a bit of a challenge. I'll have to print them out.

Edit: ok, if I manually short the brake switch wires together, the brake lights come on. So I'll have to look at the switch.


At least for the years '65 through '68, do all C-body cars share the same 3-connector bulkhead connector arrangement and pin-out?

Also, what is this? In the center of the photo. This is mounted near the brake pedal, looks like a solenoid, it has a 3-wire connector, not plugged into anything. Brass or gold-looking plate has long thin arm extending down. To the upper-right is the brake light switch, wires unplugged.

Last edited:
Not sure about the other 3 years, but the '65 bulkhead connector is different. Only 2 plugs & the red and black ammeter wires are screwed to individual buss bars.

A trick that helped me with the wiring diragram was to scan it and then use MS paint (or similar) to color the lines to match the actual wires. I think you can buy color diagrams, but I found that by doing myself and tracing the lines I understood what was going on a lot better. You can also erase the wiring for options your car doesn't have, that reduces some of the clutter.