TheSamba.com :: View topic - Dash lights go out when engine is running

Tue Jan 16, 2018 11:20 am

I'm early in the process of restoring a '73 thing and have discovered what I think is an interesting situation. I've worked through what I thought was all the electrical issues on the lights (in other words, they all work now), but noticed when I was finally able to take the car for a short drive at night that the dash lights go out when the car is running. Everything works correctly with the key in the ON position but the car not running, and everything except the speedo light works when the car is running. The only other issue is that my turn signal indicator flashes once or twice, then quits, but the turn signals keep going. I'm less concerned about that than I am the dash lights not working.

The dimmer works correctly when the car isn't running, and no amount of turning changed the dash lights not working when it was running.

Suggestions?

Tue Jan 16, 2018 3:47 pm

Just to be clear, when you say everything works when the car is not running, does that include the dash lights not in the speedometer? i.e. the lamp in the heater timer switch, the hazard light switch, and the lamp behind the defrost lever illumination bezel?

Tue Jan 16, 2018 8:25 pm

I was thinking of an intermittent ground to the speedo housing.

Sat Jan 20, 2018 11:26 am

Yes, all the lights work when the car isn't running. Though, I must update my original claim. The speedo lights are fine with the key in any position except ON, car running or not. The other lights - hazard switch, wiper switch, are unchanged with key position.

I have not yet checked grounds on the speedo. Guess I'd expect a ground to have the same effect regardless of key position.

Mon Jan 22, 2018 3:23 pm

I've given this a lot of thought. It's a tough one. First it should be said that not all the dash lights share the same ground. The lights in the speedo share a ground with the heater timer switch. It might be helpful to know if when the engine is running the light in the heater timer switch stays on, or is off like the speedo lights.

With no particular strategy in mind I would suggest tracing the path of the gray/red wire, making sure it's plugged into terminal 58b on the light switch and then following it along and making sure it is not shorting anywhere.

Mon Jan 22, 2018 3:36 pm

Heater timer switch is unaffected by key position. It stays on with no noticeable change in brightness when the dash lights go out.

I'm hoping to dig into this in the next week or so. I'll post what I find.

As always, I certainly appreciate the help!