Foglights Dead, Can't Diagnose - 2001 Surb K2500

[raueda1]

My foglights are dead and I can't figure it out. I replaced the relay and they worked for about 4 on-off cycles, then out again. Here's more info:

• fuse is good. It was good all along, never blew.
  
• There's power from fuse to the relay socket.
  
• Jumping the relay contacts that power the foglights turns them on.
  
• The relay itself tests good when removed - contacts close,
  
• I unpugged the switch/button module and tested it. It's momentary contact switch and makes contact when button is depressed. so the switch seems OK.
  
• Per the Haynes manual circuit diagram (called "Headlight system - typical") I hooked up jumpers to emulate the switch. Doesn't work, more evidence the the switch is OK.
  
• Everything else electrical seems to work fine.
  

My conclusion is that there's something someplace else that keeps the relay from powering up when the button is pushed. The whole darn system seems unnecessarily complex. It's wired through the headlight dimmer switch, park lamp relay (park lamps work OK), it's all controlled by the BCM (body control module?).

 

Anybody had a similar problem? Anybody have a fix? Thanks!!

[markw8]

I believe all the switch does is command the bcm to turn them on.

 

Mark

[Duelin]

I assume that the fog lights go off when you turn the high beams on. So you might want to check the high beam circuit to see if there is a problem.