I am working on a 2007 volvo 670. The right headlight keeps going out and coming back on. Occasionally it will flash when I turn the hazards on.
I have replace all the bulbs, both headlight harnesses, and the main linking harness. Also have replaced the light switch dimmer switch and light control module.

Now I have the whole dash off and am lost on what to look for or do. The fuses are all good. Same with the relays,

If anyone can help that would be great!!!

Thanks
Max

 

not sure about the big trucks, but if it were a regular car/light truck, I'd be looking for a bad ground with symptoms like that.

I was/am an auto mechanic, turned wrenches for 10+ years.

--Dave.

 

Thanks I am also a certified tech. I have checked all those things.

 

my buddy had this same problem on his 03 (new body style) volvo.It was doing the same thing. Volvo dealer replaced bulbs harnesses and such. I really dont have a definitive answer but we checked and tightened the grounds. The lights have been fine every since.

 

you need to get a test light and check all the wiring that feeds the headlight system on that side; use it to determine the function of each wire and then you can single your problem out. you should have a hot for low beam, a hot for high beam and the wire that doesn't fire is your ground.

i picked up a trailer a few months ago that was a real nightmare. main problem was that someone had used the turn signal hot wire to ground half the tail lights. maybe you have a similar problem.