99 Mountaineer headlight problem

[IowaBob]

While driving with headlights on low beam the lights just turn off. I can flip to High beams and continue driving. Any idea why the headlights just switch off for no reason. Its random and doesn't require any input such as turning, using the wipers or using the turn signals. Just flat out shuts of the lights.

 

[MAS Tequila]

MFS going bad.

Be glad it's your headlights, I had one once that would randomly cut out the brakelights.

 

[IowaBob]

Thanks! I'll buy and try. Hopefully that's the culprit.

 

[J_C]

The MFS is really easy to clean, remove hardened grease with a petroleum solvent (gasoline, etc) then your choice of abrasive to make the copper shiny, then some fresh dielectric grease.

Take it apart on a bench lying flat so pieces don't fly out when opening. There's about 5 x T10(?) screws holding it together.

 

[CDW6212R]

I agree it's likely the multi-function switch. I would replace it, at this age it's time to replace a lot of old high wear parts. In a 20 year old car, don't be surprised by any issue from switches, relays, electronics in general, door latches, battery cables, starters, fuel pumps, etc, etc. If the part was relatively new, I'd be trying to save it.

 

[J_C]

I didn't observe any *real* wear in my MFS, it was just that time had hardened the grease and a slight oxidized layer on the copper. Those copper contacts aren't plated or anything so if you get them shiny clean and re-greased, they should be good as new again... unless your plastic got brittle and cracked.

 

[CDW6212R]

I understand, that's normal for a lightly used part. Among the many used Fords I've owned, most have had prior hard use that shows in loose items, like the shift lever, and the MFS. I've had to replace 4-5 of them in Crown Vics, about half of the wear from myself. I'm easy on things in my normal driving, at work it's tough to baby the turn signal lever.

After 20 years there aren't many vehicles that have had light usage, are really well taken care of etc. Some parts it's just time to assume they are due to die soon.