So my son come sin yesterday and tells me that one of his headlights is out. So naturally I change it (drivers side high beam 9005). DRL works fine turn on headlights and high beam doesnt work on drivers side. Fuses ok thinking that it's the connector? Anything else that I should look at. Also changed the connector and swapped the bulbs and still no high beam on the drivers side.

 

turn the lights on and check the voltage at the connector.

 

Check all of the headlight related relays and fuses. The DRL configuration with the high beams in series can cause some weird problems.

 

Check the fog light fuse as well (marked FOG LP I think).

The DRL relay switches the "power" wire at the left High Beam between power (for high beams) and ground (for DRL's, when the lamps are run in series). The power for the coil of that relay comes from the fog light fuse. This is true even on vehicles without fog lights.

Another weird artifact of this bizarre DRL system is that one bad high beam bulb will knock out both DRL's, but only one high beam.

 

I believe this is the correct wiring schematic for your truck (attached). As Racer_X has stated, the headlamp grounding relay gets its power from the fog_lp fuse (#28 - 15A).

 

Thanks for the help so far. Sunday gonna check the fog lamp fuse and the DRL relay.

So if I am reading this correctly power for right side comes from headlamp fuse and power for drivers side (high beams) is from DRL relay.

 

Fog light fuse good. DRL relay hard to tell. It has a 4 prong relay and I swapped with another. But looks like it is spaded in the fuse box for 5 prong. Only 5 prongs are fuel pump and headlight ground. Attached pics. Any help greatly appreciated. Son has to take driving test Wednesday so I have to get lights fixed.

 

Try swapping in one of the 5 prong relays to the DRL position.

Looking at the wiring diagram above, I think it will work with a 4 prong relay in the Headlight Ground relay position. I also think it works with a 4 prong fuel pump relay, but I haven't checked the wiring diagrams for that one.

I know it won't work with a 4 prong for the DRL relay. That's true for any 2nd gen S/T series (even the earlier ones with only a DRL relay involved and no "headlight grounding relay").

 

Racer
Your were correct. Replaced DRL relay with a new 5 prong and headlights working great. Thanks for the help.