Low and high beams aren’t working

[mr2crazed]

Both headlights (low and high beams) went out at the same time on my son’s 1997 Explorer Limited. It’s equipped with the auto light feature. The fog lights still work.

I have 12v at fuses 4, 8, and 33 which confirms the headlight switch and multifunction switch are functioning. I’ve also located the headlight relay under the dash and swapped with the parking relay and still no headlights.

I removed the center console systems check unit hoping to find the LOM (lamp out module) but there isn’t one present.

Any other ideas?

 

[C420sailor]

Check for good ground at headlight bulb sockets. I think these headlights are positively switched, so a bad ground would kill both.

 

[J_C]

and while the headlight socket is out checking for ground, also check for 12V on it.

 

[mr2crazed]

and while the headlight socket is out checking for ground, also check for 12V on it.

and while the headlight socket is out checking for ground, also check for 12V on it.

SOLVED.
I checked the ground at the socket and was good. So for grins I decided to check for 12v and wouldn't you know it, there was 12v on the low beam connector when power was applied. Checked high beam with power applied and also had 12v. I pulled the bulbs on both sides and they both had exploded at the same time.

This led me to the start of the issue on the auto headlight unit on the rearview mirror. The switch on the mirror was causing all the lights to flicker which must have applied a surge to the headlight bulbs. Installed brand new bulbs, disconnected the cable at the rear of the rearview mirror thusly disabling the auto-headlight feature, and it's back on the road.

I sure did learn a lot by researching and reading this forum.

 

[J_C]

I doubt flickering caused a power surge, just wore out the bulbs because turning on, expanding while heating up is the moment of most wear to an incan bulb filament.

You might try spraying some contact cleaner into the slider switch, and moving it back and forth several times before the cleaner dries, BUT I don't know if that would cause any problems with the back of the mirror coating. Ideally the mirror would be opened to more precisely put contact cleaner only on the slider and if it has metal springy-contacts that have lost tension, bent a slight bit more tension into them. If they used a petroleum grease on the slider tracks like they have on other control components like the MFS or interior rotating switch, it may be just a matter of a solvent to rinse away old, hardened grease, then ideally a very thin film of dielectric grease would be applied.