Ndeiter18 Posted July 14, 2021 Share Posted July 14, 2021 I have a 1990 Mack r model the headlights do not work but work when flipping the curiosity switch. Anyone have any ideas thanks in advance!! Quote Link to comment Share on other sites More sharing options...
0 Joey Mack Posted July 14, 2021 Share Posted July 14, 2021 assuming you checked fuse,breakers,bulbs, etc.. I have found that where the harness passes thru the P-Clamps toward the front, they will cut into the wires, also look and see if the wire harness runs behind the oil filters and oil cooler along the block and look there for cuts and wear.. 1 Quote Link to comment Share on other sites More sharing options...
0 Rob Posted July 15, 2021 Share Posted July 15, 2021 I've seen that toggle switch on the upper dash bad more than once..... 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
0 JoeH Posted July 24, 2021 Share Posted July 24, 2021 Are you flipping the headlight switch on the dash up or down? Up is headlights, down is clearance lights, middle is off. The switch up on the left of the dash is a high beam momentary switch. It doesn't activate low beams. If you're flipping your switches properly then start with putting new bulbs in and checking the wiring as mentioned above. You can lose a low beam filament without losing the high beam filament in a bulb. Quote Link to comment Share on other sites More sharing options...
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Ndeiter18
I have a 1990 Mack r model the headlights do not work but work when flipping the curiosity switch. Anyone have any ideas thanks in advance!!
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