98 S10 headlight issue

[Kevo22]

I have a 98 s10, with a headlight issue. the headlight don't work very often. Just every once in awhile will they decide to come on. When they do come on they are very dim, but the brights are still bright as can be. I've replaced all bulbs, nothing changed. When you start the truck the drl's still try to turn on so the parking lights still work but the brights indicator is also always on. And when the headlights or parking lights are on the back passenger brake light and turn signal become very dim so you can't see it even at night and the turn signal indicator flashes very quickly like it has a bulb out. Any Ideas?

[MagicRat]

I suspect the ground wire to your headlight bulbs is bar, with loose/broken wires, dirty contacts etc.

[Kevo22]

I've looked at ground wires, taken off and cleaned. Nothing different today. I've figured out that only the brights are working, the low beams don't work at all. When I switch from bright to low beams it's just the brights getting dimmer it doesn't actually switch from high to low.

[Blue Bowtie]

Check the diode in the UEC with an ohmmeter set to the Rx100 or Rx200 scale, or on the diode check scale ->|- if it is so equipped. Meter it in both directions an report the results.

Check the continuity of the DRL relay NC contacts. The headlight ground operates through that relay.

Check the headlight ground relay contact continuity as well.

A quick/dirty way might be to swap the Headlight Ground relay with the Fog Lamp relay, or any other relay with the same part number, then do the same with the DRL relay.