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1978 Mark High Beams Stay On

Hey Bill,

My question to you is that the high beams are staying on, no matter what I do they will not turn off, I have tested the switch on the floor and it's good. It has the auto feature for the lights, and the switch function is good and tight. Is there something I am missing?




Hello Jon,

Some of these " Autolamp " systems can be difficult to diagnose without the Factory Shop manual and wiring diagram as they use relays and amplifiers that can fail. Have you tried turning off the Autodim and the Autolight tabs at the main headlamp switch on the dash to find out if the headlamps operate properly in the manual position? When you tested the foot switch did you do a continuity test in all positions? We have seen these switches lock up and seize on many vehicles. In any case and because you are a parts customer at Lincolnland I will ask George to send you copies of the necessary " Autolamp " section from the FoMoCo service manual. You will then see where the 4 amp inline fuse is located above the dimmer switch and be able to check if any critical components are unplugged etc. This section should also offer diagnostic procedures.