odd dash light issue

[mr_miles]

I recently got a new issue with my 77 280z. all of my dash lights stopped working except my heater selector bulb. I've checked everything I can think of, fuses, grounds, I checked the bulbs and they're good, even changed the rheostat. all my other exterior lights still function normal, dome light still works. I'm at a loss as of what to check now. anyone else have a similar issue, and what did you do to fix it?

[datzenmike]

Does the heater bulb adjust for brightness?

[mr_miles]

Apparently, it does not. I could have sworn it did after I installed it....

[datzenmike]

Replace a suspect fuse, they are never to be trusted and certainly not visually. Make sure the fuse is securely held by the clips.

 

The lamp dimmer has a ground on it. Maybe make a temp. ground wire and touch to it and see f they come on.

[mr_miles]

All fuses are brand new and all fuse contacts have been cleaned with fine sand paper :)  I'll give the ground a shot.

[datsunaholic]

The exterior parking lights get their (+) voltage from the same source as the dash lights- through the same terminal in the headlight switch (the running lights are actually at the end of the chain, so if there was a break in the wiring they'd be the first to go) including the same fuse.  The only thing common to all the dash lights but NOT the running lights is the dash lights go through the dimmer for their ground.  Including the heater light, so it should dim with the rest of the lights.  

 

The heater illimunation light is one of the furthest lights (electrically) from both the dimmer and the light switch, but a couple things are further away (the ash tray light, the hazard switch illumination light, and the automatic trans shifter illimination light for A/T cars).  The rear running lights split off between the heater and console lights (electrically), but don't use the dimmer for ground (naturally).

 

This means it doesn't make sense that the heater illumination light comes on with the headlights, but isn't dimmable.  Unless it's plugged into the wrong plug, since it's pretty close to the A/C switch wiring that use similar if not the same 2-wire plugs (then the light may come on with ignition, but not with the light switch).

 

I suspect the dimmer isn't grounded, though. 

 

 

 

^^^ The above only applies to cars that haven't had their wiring all hacked up though.  I had a truck that someone had crosswired the running lights to the main headlights because the running lights kept blowing the fuse, so I was chasing ghost wiring and a missing dimmer)

[mr_miles]

oh snap. that makes me wonder if I plugged it in wrong when I was fixing my heater. it doesn't dim with the switch but it does turn off with it. also, my wiring has been tampered with prior to me getting the car. I have 3 kill switches to start it, one for heater, one for engine power, and one for stereo. I recently started re attaching my running lights as they were not hooked up. one currently works and one has a burnt bulb, haven't finished the other two yet.

[mr_miles]

ran a ground to it, nothing. does it matter where i put the ground on the switch itself? i did it on the body of the switch as it looks to me like it creates ground where it touches the dash frame. I suspect sonehow my running lights are the culprit. after I fix my leaky wheel cylinder so its driveable again, I'll tackle this issue once more.

[ggzilla]

Grounding the switch won't do anything. One of the wires going to the switch is a ground wire. Check the wiring diagram.

[mr_miles]

Will do. It's kind of hard to trace wires upside down sometimes so i figured I'd start there :p