My mom out in the san bernadino mountains picked up a 98 Dur for a mountain/snow/cargo truck (DD is a 02 firebird).

She said one night, neither headlights came on, she turned the switch off and back on, only the driver side works.

Any idea on this, or what harnesses to check?

 

I would say the switch is fubar.

 

The switch controls both heads independently? I don't have an FSM/diagram for the pre-00 or I'd look myself.

 

Well the fact that she turned on the switch and nothing happened, turned the switch off then back on and one light worked. Sounds switch related to me.

 

+1 the switch is suspect, i would also start by checking grounds, idk if they have a shared ground or not.

 

I'm not sure where exactly the grounds wind up beyond the relays, but I know for sure that the headlights have a common positive and then switched grounds for low and high.

 

are they independently (L/R) switched relays or are they common mode ground?

 

Looks like they share a relay.





Here's a link to the FSMs: https://www.mediafire.com/?xu9h0gt9bdcn6

 

So she thinks that both dont work in low beam but one does in high beam. I told her to go find out and report back.