Hey guys, figured I’d ask here before tearing the wiring apart on my car. Also, my chassis service manual should be here tomorrow, so I’ll have wiring diagrams and trouble shooting charts available to me tomorrow. Onto the problem.

71 Cutlass 442. With the lights turned off the tail lights work. Indicators don’t, but I’ve got some spare flashers I’m going to swap in tomorrow to hopefully solve that (it just got dark here). The main problem is when I turn the head lights on. If I put my parking lights on everything works fine, but if I turn the headlights on I lose all my tail lights. Any clues where to start looking?? Thanks in advance!

 

The headlight switch has an internal jumper that turns the tail lights on through the brown wire in both the park and full headlight on positions. If it works in one position and not the other I'd say its a headlight switch problem if the stock wiring has not been messed with.