Head light problem

[SMason]

Buddy has '04. Left side headlight brights will work, dims dont work. We hooked up a test light and with dims on the test light blinks. We double checked all wires and connections. But with the dims on the test light blinks at a timed rate it seems like. So wonder if anybody knows why it blinks or has had same problem. If ya could help thanx

 

[Pawpaw]

If he's not getting a "lamp out" indication on the instrument cluster, I would suspect the headlamp relay.



On the 3rd Gens, the headlight switch does not directly turn on the lights. It just closes a circuit to the ECM. The ECM turns on the headlights through a relay.



You can download a service manual, complete with wiring diagrams from www.hemitruckclub.com



Bob

 

[jelag]

I assume that the headlights have circuit breakers or something in the ECM to control current... by law headlamps can't be fused so in a direct short... they blink on and off with the current draw to get the vehicle off the road...



You have a failed relay, failed circuit breaker, or control ECM to the lights... my F550 has one of these. . don't know its exact name... . or you have a grounded wire which is tripping the breaker or control module... .



Hope this helps. .