lights on 1991b2600 the dim work but bright dont work is there swich need

 

it could be the switch, or it could be the bulbs. turn your lights on then high beem, then unplug the headlight and use a 12 volt testerto see if you have 12 volts getting to the bulb, if you are, it's the bulbs, if not, it's probley the switch. hope this helps

 

with our trucks its more than likely the combination switch

 

If it's the switch itself I'd probably install a momentary switch on the dashboard or the underside of the steering column, as the replacementignition switch wires are quite expensive (but try cleaning it first). The replacement is really the switch part and three separate harnesses cabled together: one for headlights,one for ignition/starter, and one other that I can't remember (maybeturn signals). I do remember when I replaced mine 10 years ago ($103 at the dealer, but in stock) that I should've just repalced the ignition portion, as that would've saved me efforts.

 

If it's not the switch and the bulbs. Try checking the wires. It might be wiredly wrong. But most probably, in the mazda headlights, bulbs are the first to breakdown than switches.

 

OK, I re-read. If the low beams work but the high beams both don't, and the sealed beam bulbsthemselves are OK for both filaments, it's probably the dimmer relay, a square box under the dash, driver side. You should be able to hear it click when you try to switch from low to high.