Topless Stang

Just like the title says my light switch no longer lights up. I thought the switch was at fault so I dismissed it as I planned on swapping a new oem switch w/fog light control. Well I installed the new switch and still have the same problem. I have my boost gauge tied into the illumination wire on the light switch harness and that still works. I haven't made any other changes to the wiring, it was working then all of the sudden it just stopped. Does anyone know what wire in the harness controls the switch illumination or if its tied in to something else?

IamNobody

Check the ground going to the switch. It sounds like there is possibly an internal wire break somewhere between the switch and where you tapped into for the boost gauge. Maybe the boost gauge is causing a problem?

Topless Stang

It's worth a look, but the boost gauge was installed and working for a few months or so before the switch stopped lighting up.

Nuke

Have you confirmed you have voltage beyond the tap point for the boost gauge? You could have a bad tap/splice.

I'd connect an independent power source to both the old and new switches to confirm that the light does (or doesn't) work on each on. It's not likely that you bought a new switch with a bad bulb but it is possible.

157dB

Yep, a volt meter or test light would make short work out of the diagnosing of the problem.
If the ground to the switch was bad, nothing would work but the headlights (that you
now cannot turn off).
The switch grounds an input turning OFF the headlights. Its a failsafe mode
that makes the headlights come on if the switch or switch ground becomes bad.
When you remove your headlight switch from the connector to replace it with
one with the fog light option, the headlight should come on by default.

Topless Stang

Thanks for the replies. I must admit I let this go. I installed my fog lights and harness and the switch controls everything fine. The light for the fog lights comes on telling me when they are on, but the switch itself is still dark.

157dB

This has been an issue before
with the bulb (incandescent)
prematurely burning out.
A post was made about the
availability of the bulb to
replace it.

https://mustangforums.com/forum/2005...itch-bulb.html

Topless Stang

That's a great find! I bought my fog light oem switch used off of eBay. Since this is a common problem that switch may have had a bad bulb too. I'll definitely be checking that later today! Thanks again!

Matt's 95 Stang

This is a great thread. I just noticed about two weeks ago that my switch was not illuminating. Now I know that its not just me. Thanks for the help guys.

Matthew

Topless Stang

I finally checked mine and yes the bulb was blown and the plastic housing was melted.