Help, Fog lights no workie!

[Diesel Nut]

Got up this morning, pured some coffee and went out to start the beast. I like to let er warm up a bit before the long 4 minute commute to the job site. So, load up the lunch bucket and climb in. I turn the parking lights on when idling until I get out of the RV park so's not to get anyones panties tied up at 6 am. Well, I pull up to the stop sign and twist the switch for head lights. They say good morning. Pull on the switch for fog lamps and they come on for about 10 seconds then go out. WTF? So, I reset the switch. No luck. Messed with it a bit and finally gave up. Bummer. However, the indicator light on the switch says they are on. Odd.

So, I get back to the 5th wheel after work and check the obvious. Fuse 41, just fine. Pulled the fuse, got no indicator light, put the fuse back, indatactor light comes back on. Very odd. Ok, maybe its the relay? Checked that too. Not only can you hear it clicking on and off, but tried 2 ither relays from under the hood that I KNOW work, and still no lights. But as far as the indicator says, all is well. Haven't pulled the bulbs yet to see if I blew both at the same time. What are the odds of that happening? So, anyone have thoughts?

 

[Alan Reagan]

I wouldn't think both would blow at the same time. You might check the wiring down in the bumper area up to the harness. Doesn't sound like chaffing because the fuse is OK. Might be a loose connector down there.

 

[Diesel Nut]

Checked the connector at the bumper and it was tight. When I can run into town and get a test light I will check to see if I am getting power to that point.

 

[Diesel Nut]

Anyone else have ideas? This sucks driving in the fog with no flippin fog lamps! #@$%! #@$%!

 

[Alan Reagan]

If you checked and there is no power at the bumper connector and the relays are working, then you have to track the light blue wire from the lamps back to the PDC. Unless they've changed colors, the LB is the wire that controls the lamp power from the relay. The Red/Orange should go to the fuse that you have already checked. It's the light blue wire portion of the circuit between the fog lamp and the relay (PDC) that's not working. There are no other connectors between the one at the bumper and the PDC. There is one indicated splice between the connector and the PDC that takes the light blue wire to the fog light indicator.



If the relays are working, the I assume the switch is OK and that the headlights are not on high beam (which disables the relay).

 

[Diesel Nut]

Head lamps work in both high and low beams, but have no effect of fog light issue. I haven't yet checked for power at the bumper or for blown bulbs. The indicator light on the headlight switch will show that foglamps are on, even though they aren't. Did you pull this info from the service manual? I NEED to get one of those!

 

[Alan Reagan]

Yes, it came from the service manual. And, yes, the indicator will come on even if the lights aren't working based on how it is wired. If you have power at the bumper connector, then it is your lights.