dmechnic

Hello all. I’m adding some interior lighting that I only want on when the parking/headlights are turned on. All the tips I’ve read state the rear tail light parking light wire is the easiest place to accomplish this. Pulled the tail light, saw that the marker light has red/blue & black wires. This checks with what I’ve read so far. Spliced into the red/blue and decided to check continuity as the connector kinda fought me. In checking continuity I have found that, with the battery out of the car and the headlight switch in “off” I am showing continuity with both the red/blue & the black wires to the chassis. What gives?? I’d expect the black to be ground and test positive to chassis but shouldn’t the red/blue test negative to the chassis? These cars and their damn electrical systems, I swear. Any insight would be greatly appreciated.

EDIT: I threw a low amp 12v charger on the terminals to see if the marker light worked as intended as the bulb happened to be burnt out. Works exactly as intended. I just don’t get why both wires test positive for continuity to the chassis.

karlt

The rear tail light and side marker light are wired in parallel. If you pull the side marker bulb and test continuity of the red/blue wire to ground, the circuit will be complete through the tail light.