Hello out there-
Hope someone can help me, I have upgraded my /81 F350 headlights to H4 90/100 watt bulbs, & now the head lights start to flash after a while, seems to me they flash due to heat, hence the delay till they start to flash.
The truck can be running or not, I think its the switch & have ordered one in case, I did notice that the harness has a slight burn mark next to one of the terminals.
Is there something else I should check, in case its not the switch,



thanks

 

The switch has a circuit breaker built into it. The new switch may help, but you still may have problems. The switch barely has enough to drive the original headlights, so the larger headlights are going to always give you trouble.

You may need to re-wire with relays.

 

So what your saying is that I might have to bypass the original switch & wire in regular toggle switches?

 

That's one way to do it, but another way is to snip the headlight wires out at the headlights, and wire them to bosch type relays. So when you turn the headlight switch on, all it does is turn the relay coils on.

Then you run a heavy fused wire from the battery + over to the new relays. You hook this new power feed to the relay contacts, and hook the headlights back up on the other relay contacts. So the power for the headlights runs directly from the battery, through the relay contacts, and then to the headlights, instead of running all the way into the cab, through the headlight switch, and back out to the headlights.

There are a couple of articles on how to do this in the tech section of this website.