gavin68

I have a rather perplexing issue with my dashboard lighting (basically the circuit that controls the back lighting on the dashboard, radio, and climate control). The circuit always come on when the headlights are turned on, but the dimmer switch has no effect in either dimming nor turning the lights off.

I can turn the switch all the way to the OFF position, and the lights are still on. Then turn the brightness all the way to the maximum, and it is still on and the brightness doesn't change. It's not obnoxiously bright, but this is annoying and I would like to have a functional dimmer switch. I have searched online, and some people have had a problem with the lights not illuminating at all, but I am having the opposite problem and I have not seen anyone else with this issue.

I have tried replacing the dimmer switch with one from a junkyard Maxima, but the problem still persists. The old switch did work until about a year ago. Anyone have any ideas?

DennisMik

iTrader: (2)

While there are a couple of lights that are not on the dimmer switch, the a/c controls are. Do any lights in other places, such as the lights in the console for the shift lever dim when you move the switch?

gavin68

I forgot to mention it, but the shifter console light is also unaffected by the dimmer switch.

DennisMik

iTrader: (2)

That answer tells me that the problem is not the a/c control unit itself.

There are only 3 things that can cause your problem.

1 - a bad dimmer switch
2 - a shorted wire in the wire harness
3 - improper installation of the dimmer switch.

I don't know if #3 is actually possible. I rather doubt that it is, but theoretically it could be.

#2 is a maybe, but I would expect something to burn and smoke, the wire harness or the dimmer switch (or both). You unplug the wire harness from the dimmer switch and check the red/yellow wire (the middle one) for continuity to ground. You don't want continuity to ground on this wire.

#1 the dimmer switch - the most logical thing. You did put in a used one and maybe Murphy's law came with it.

gavin68

Ok I'll have another look later, thanks for the info.

gavin68

Sorry for resurrecting an old thread. I still have the same car and the same issue. When I said "I'll have another look later", I didn't mean five years later lol. Life happens.

I unplugged the dimmer switch and turned the headlights on. Looks like the dash lights (and related lighting in the HVAC and shifter) are still coming on. I also used a voltage meter to test continuity on the middle red/yellow wires, as DennisMik suggested. I'm not too familiar with how testing continuity works. I connected the other end to the black Ground wire, and it beeped (meaning there is continuity). I also connected the other end to a piece of metal (the steering column), and it beeped as well. I guess I will need to find some wiring diagrams and figure this out. I did not see any damaged or spliced wires.

Has anyone else had this issue? I can only deduce that there must be a crossed wire somewhere, but I have no idea where to begin searching for it.

gavin68

SOLVED!

I found the problem. It turns out that Dennismik's prediction #2 "2 - a shorted wire in the wire harness" was correct. Long story short, a path to ground existed where it shouldn't be. I had to unplug a few parts to try to isolate the problem. Sure enough, the lights shut off when I unplugged one of the radio connectors:






Here's what the diagram for the dimmer switch circuit (Red/Yellow wire) looks like:



The Red/Yellow (R/Y) wire runs to several devices, including the car stereo. The stock radio has connectors that connect to the dimmer wire, as well as a Red/White wire that signals when the headlights are turned on (to dim the interior lighting at night). However, I noticed that the R/Y wire was connected to an Orange/Black wire on the other side of the connector. I followed this O/B wire to an odd spliced connection:



Frankly, I'm not sure how this happened. I think a younger me might have incorrectly thought this was a ground wire (since there was a Black stripe) and spliced it into the ground connection, probably about 8 years ago. However, in doing so, it bypassed the ground connection on the dimmer switch with a brand new path to ground for the interior lighting. I did some further research and found that some aftermarket stereos might or might not actually have a connector for the dimmer wire. Evidentially, my aftermarket stereo does not have such a connector. In the event that your stereo does not have a dimmer connection, the dimmer wire should not be used. In this case, I mistook it for a ground wire and screwed up.





The solution was simple. Just cut the dimmer wire off, and put tape over it to avoid any inadvertent connections. It still dims along with much of the interior lighting when the headlights are turned on, as intended.

Bradley Dyess

What did you hook the red/yellow wire up to?

gavin68

This is part of the mega connector (not sure if that's the proper term). I thought the orange/black wire was a ground wire due to its black stripe, but it's not. It's part of the dimmer system.