Head light switch problem, please help

[straws]

I have a 1991 Mustang without fog lights. We have a wierd problem. The headlights work, but all the parking and taillights will not work at the same time. If we play with the headlight switch a little bit, and leave it in a position about 3/4 way on, all will work, unless you bump it.

I swapped out a new switch, and the exact same thing is happening. I heard a relay clicking on when the park lights would work, and I swapped it out as well with no new results.

Does anyone have an idea what is going on or where I should check?

Sorry if this is not in the right forumn, I did not see one that matched my question.

 

[BlownFiveLiter]

Moved to 5.0 Tech.

It's very likely that you have an issue with the multi-function switch in the steering column. Ford, in its inifinite wisdom, ran the full-amperage through both switches and over time the wiring degrades and causes resistance, which ends up melting the harness and contacts inside the switch. Latemodel Restoration (50 Resto) sells new pigtails for the headlight and multi-function harnesses, and sells the switches as well.

 

[HISSIN50]

I might have misunderstood what is happening. That said:

Was the headlight switch you swapped in new or used?

The parking lights (including the front and rear marker lights) are powered only via the headlight switch. If there's an issue keeping the parking lights functional with a change in the headlight switch position, that's likely a headlight switch issue or headlight connector issue IMHO.

 

[straws]

Fix to the headlight switch problem

Well color me stupid. The left headlight had literally exploded the glass, so we changed it out. But then the park lights would not work unless you fiddeled with the switch, I could get one set of the other to work. It was very strange.

Nonetheless, I found the issue. The headlight must have blown the 15 amp fuse for the park lights. The red herring was the oddball. Just by playing with the switch I could get them to work by playing with the switch.

End result is it is fixed.

 

[dcurtis]