99XLT with flashing headlights

[StarGehzer]

I see flashing headlights are not uncommon on these trucks.

My 99 Explorer's headlight have a problem.
When I start the truck, the headlights are dim for about 10-15 seconds and then they start to flash about once per second.
Both lights flash at the same time.
After 5 seconds or so, they start to flash faster & faster.
Once I turn on the headlight switch, they are fine, until I turn it off again.
The truck does have daytime running lights.
There is no security system.
All wiring is original.

Reading other posts leads me to think there might be a circuit breaker or thermal device tripping & resetting. Where would that be located?
If it is a device tripping, I guess I need to check the amperage to figure out if there is a short or if the thermal device is defective?

I guess there could be a problem with the DRL module. How can I test it or confirm that is the problem?

Any other ideas?


Thanks

Vince

 

[BrooklynBay]

Welcome to this forum! Check the ground connections on the headlight's wiring harness.

 

[StarGehzer]

Good idea BroklynBay! Although the flashing is so regular that it isn't just a loose connection that's wiggling. It could be drawing higher amps due to rust though.
Since the problem is cleared when I turn the light on manually, does that suggest a particular ground location?

 

[BrooklynBay]

Maybe it's a problem with the ground on the auto headlight module? Do you have a wiring diagram?

 

[StarGehzer]

Yes thanks, I have a set of diagrams.
Soon as the rain stops I'll check it out.

I see on the diagrams the grounds are labeled as "G104, G105 etc.
I don't have the diagram that shows the locations of those points, but I'll see what I can find.

 

[budwich]

its your daylight module trying to "reduce" light levels.... probably on its way out.