YPJ

Looked through the wiring diagrams I could find and still am left with a question. Hopefully someone can confirm what's going on.

I installed aftermarket headlights on my 06 screw fx4. These have separate bulbs for high and low beam. Last week the driver's low beam went out upon powering on in the morning. Thought it was just the bulb. However, new bulb does not work either. Here's what I've checked:
-Whole pass side working without issue
-Driver's high beam works (so ground is good at harness which bulb plugs into)
-Low beam fuse is good at in-cab fuse box
-Low beam fuse slot IS getting power (tested w/ meter)

So basically what I have is power loss somewhere between the fuse box and the headlight plug. Is there any fuse or anything else in between that could have blown? I'm at the point where I'm about to pull the fuse box down, tap a new wire into it, and run that new wire all the way to the headlight. I figure it's a long shot, but if anyone knows of something that could be going on here that I'm not thinking of, please let me know!

GrnMachine210

What parts does the aftermarket lights include? Also check relay for any issues

YPJ

Aftermarket lights have a factory matching 3 pin plug- ground is shared and the high and low beam hot wires go to their respective bulbs. Easy swap, factory match (everything was working well for the last year that I've had these installed). Just not getting power to the wire leading to the headlight. I will check relay today.

YPJ

Know where the relay for low beams is...? Only see a relay that mentions high beam. Hopefully it's just the relay, but I need to know where to find it. Attached is the OM page that describes the relays in the fuse box of the cab.

GrnMachine210

Is that the only page? I know in my manual there are numerous pages with fuses/relays

YPJ

This is the only page that references the relays present. The preceding pages are just for the fuses (which I checked already). The only other relay reference is an engine compartment relay box, but the only lighting-related relay in there is for DRL and DRL high-beam disable (my truck does not have DRL).

YPJ

Checked wiring harness at the fuse box- no voltage to driver's side low beam pin. Somewhere in the fuse box there's a bad (or fried) connection. Pulled fuse box out and started to dig into it. Decided against removing all 100 fuses and relays and disassembling the circuit boards (at the risk of screwing up something else in the process). Reinstalled fuse box, plugged all harnesses back in, and ran a wire from passenger low beam hot to driver's low beam hot. Everything works, although not to factory specs. Oooooh well- Not the worst hack job I've done...