Fog Light Troubleshooting

[Echo]

Why do I always seem to get the weirdest issues?

Anyway, 2002 Tahoe. I'm attempting to wire Nilight LED pod lights to my factory fog light connectors and running into weird problems. They won't come on at the switch. I've checked the fuse, its intact. I've tested the relay with a multimeter and a click test, and it operates as it should. I've even used a spare relay just in case. My grounds are good, and the circuit completes when i use a jumper wire at the relay, activating the lights. I replaced the factory switch with an aftermarket variant. The wires at the switch all test properly. Its almost like the switch isn't activating the relay. Anyone have any ideas?

 

[JoeBlobs]

Does seem odd. How did you wire the LEDs to the fog light circuit?
With the lights disconnected and switch on, do you have power at the end of the wire?
Does the dash light come on when you activate the switch?
How are the lights grounded?
Have you bench tested the lights?

 

[Echo]

Does seem odd. How did you wire the LEDs to the fog light circuit?
With the lights disconnected and switch on, do you have power at the end of the wire?
Does the dash light come on when you activate the switch?
How are the lights grounded?
Have you bench tested the lights?

I wired them using a GM 2 pin connector, like the factory fog lights have. I do get power at the end of the wire, but only when I bypass the relay with a jumper wire. The dash light does not activate, but the LED on the switch does. The lights are grounded via the black wire provided on the factory wiring. The lights have been bench tested, and turn on when using the mentioned jumper wire.

 

[JoeBlobs]

I replaced the factory switch with an aftermarket variant.

It sounds like everything is operating as it should except the switch. Can you elaborate on the aftermarket switch situation?
Was the factory switch inop?

I'm not 100%, but I think the factory switch triggers a computer, which then triggers the relay. I think we can narrow it down to switch to computer and/or computer to relay.

Maybe someone can verify the circut setup or you can find a wiring diagram.

 

[Echo]

It sounds like everything is operating as it should except the switch. Can you elaborate on the aftermarket switch situation?
Was the factory switch inop?

I'm not 100%, but I think the factory switch triggers a computer, which then triggers the relay. I think we can narrow it down to switch to computer and/or computer to relay.

Maybe someone can verify the circut setup or you can find a wiring diagram.

I think this is exactly the issue. I think the factory switch is set up to communicate with the BCM to activate the circuit. The factory switch was destroyed beyond repair, so i replaced it with a simple 20A toggle switch. I separated the 3 wires from the factory switch circuit board (which also runs the rear wiper) and put them on the new switch. Black was ground, Orange was Switch/Load, and Purple was Supply. I'm sure i was supposed to tie in a 4th wire somewhere to signal the BCM, but i could never find out what it was, or where it was supposed to go.

Ultimately, i got tired of chasing my tail and i just ran all new wiring, which works as it should now.

 

[JoeBlobs]

Ultimately, i got tired of chasing my tail and i just ran all new wiring, which works as it should now.

Thats what I was going to suggest next ha!
I'd bet a working factory switch would solve the issue, but glad you got it either way.

 

[Fless]

Late to the party, but www.charm.li has the circuit description and the wiring diagrams. When you get to the site, use the links at the top to navigate to your particular year and model, and find the info that's specific to yours.

https://charm.li/Chevrolet/2002/K%20Tahoe%204WD%20V8-5.3L%20VIN%20T/Repair%20and%20Diagnosis/