Dash lights out....not the dimmer switch

[black93lx]

My dash lights are out on my 91 LX. i replaced the dimmer switch with an ebay purchase, same result as the original switch. interior lights go on when i turn the dimmer switch, but no dash lights. The high-beam light comes on, the light below the high beam light comes on when i turn the key forward. turn signals and hazards work. check engine light and air bag light work.

thoughts?

saw a thread about the multifunction switch but not sure what that is, where it's located, how to troubleshoot. i'm more mechanical than electrical.

 

[Saleen0679]

Fuse.

 

[black93lx]

checked, all looked good. will double check to be sure but i'm pretty sure that's not it. I checked the 5 amp fuse and the 15 amp fuse (i forget the numbers) but the ones the service manual says could be the problem......also checked the others.

any other thoughts?

 

[Saleen0679]

You're going to have to break out the meter and find out where your losing your power. Did you test the 'new' switch before you installed it? It could be bad too since no dash lights is the most common fault with these switches.

A diagram for Instrument Illumination can be found at Instrument Lights Wiring Diagram Please... - Mustang Forums at StangNet

 

[black93lx]

thanks for the info.

how do i test the new switch? i've got a Calterm 66430 for reading volts, ohms, amps, etc...

and how would i start trying to trace down where i'm losing power? i appreciate the patient, haven't had much experience with electrical systems.

 

[Saleen0679]

If your dimmer is one of the old style aluminum case units then you need to set the meter to a low resistance (ohms) scale and probe across the two silver colored terminals. While holding the probes across the terminals turn the dimmer knob and watch the meter. It should be a fairly smooth increase/decrease in resistance without any 'drop outs' in the reading.
If you have the newer plastic case switch then you probe across terminals R & 1. The identifiers are molded into the case next to each terminal.

To trace for power follow the circuit diagram and check for voltage along the dimmer switch circuit. Take the negative probe and connect it to a metal chassis part/screw and take the red lead and probe the connection points along the circuit. The BR wire behind the main light switch that goes to the back of the dimmer is a good place to start. With the main light switch in the Park position you should have about 12v at both points.

 

[FrankenStang]

Check your headlight switch.

 

[black93lx]

thanks saleen0679. just what i was looking for. will test it out.

 

[jrios6450]

Im having the same problem but mine works sometimes out of nowhere and the next minute it will go out.