Fog lights don't work on 2003 silverado

Hi all,

Just got my 03 silverado 2500HD Duramax a few weeks ago. I love the truck, and I had the dealer replace a lot of stuff to make it agreeable, but one thing I forgot to check were the foglamps. I removed the bulbs, and both work when voltage is applied. I click the switch on in the cabin and the little orange light on the switch lights, but that's it. I used to get the indicator in the instrument cluster (it still didn't work though) prior to the dealership having to replace my instrument cluster for a gear select problem. Is there a relay that is an achille's in this truck, or what other electrical gremlin could be causing this annoying problem?

Should be a separate fuse for the fog lights, and a relay, too. They are typically located on or under the driver's side of the dash, but find a repair manual or online to be sure. If these are okay, then check for proper grounding. Good luck!

Hi all,

Just got my 03 silverado 2500HD Duramax a few weeks ago. I love the truck, and I had the dealer replace a lot of stuff to make it agreeable, but one thing I forgot to check were the foglamps. I removed the bulbs, and both work when voltage is applied. I click the switch on in the cabin and the little orange light on the switch lights, but that's it. I used to get the indicator in the instrument cluster (it still didn't work though) prior to the dealership having to replace my instrument cluster for a gear select problem. Is there a relay that is an achille's in this truck, or what other electrical gremlin could be causing this annoying problem?

if the electrical is good[relay], it is possible that the bcm needs programing or is defective...

I finally got around to doing some investigation. Turns out the left front element was intermittent. The right side had broken wiring. So, I replaced the left bulb and re-soldered the right side wiring and all works now. The final step was to crack open a beer to celebrate.

I finally got around to doing some investigation. Turns out the left front element was intermittent. The right side had broken wiring. So, I replaced the left bulb and re-soldered the right side wiring and all works now. The final step was to crack open a beer to celebrate.

these fog lights are not securely mounted...this vibration does damage the bulbs and on my vehicle the lights would vibrate going down the road...so I used a rubber sealant to lock in the lamp housing ,,this has stopped this..also here in the rust belt they get blasted with road salts/chemicals so I use dielectric silicone grease on the connector pins..

What kind of rubber sealant? I was thinking about using clear silicone. And the connector broke about an inch back of the plug on mine. Just had to clean it up and solder it up. Then i epoxied the end of the plug where the wires mate up to defray the possibility of vibration killing the solder job.

What kind of rubber sealant? I was thinking about using clear silicone. And the connector broke about an inch back of the plug on mine. Just had to clean it up and solder it up. Then i epoxied the end of the plug where the wires mate up to defray the possibility of vibration killing the solder job.

ya the clear silicone rubber this way if required you can remove...
on the connector the epoxy sounds good..and you soldered the wire connections ...

the connector electrical pins to socket I used a silicone dielectric grease ...this way the connector does not corrode..

Does anyone have a copy of the wiring diagram for the fog lights. I installed mine and they are on constantly. I added the factory switch and relay and after market factory like lights. The BCM is programmed for fog lights and I am wondering were I went wrong in the wiring since the only wires I added are the common and ground from the relay under the hood to the lights. Could any explain what RR FOG LIGHTS are? There is a relay location inside the truck with this label. Also the lights are also affecting my trailer lights.

bump

I have a similar problem with my 2003 Silverado (Duramax) K2500HD. When I turn on my Fog Lights, the orange light on the button illuminates, and the front parking lights come on? The Fog Lights "ON" light does not illuminate on the Dash Console. I think that bot of my bulbs are good; any suggestions?

What is the "BCM?" How do you reprogram it?

Thanks in advance.

I figured mine out. The fog lights throught the factory wiring is a positive ground system. Do not connect the ground leg on the relay. There are only tree wires connected on the relay two to the switch and the third positive to the lights. Ground the lights at the light itself. Not at the relay.
If the lights are on constantly dont worry about the BCM its already ready.

I figured mine out. The fog lights throught the factory wiring is a positive ground system. Do not connect the ground leg on the relay. There are only tree wires connected on the relay two to the switch and the third positive to the lights. Ground the lights at the light itself. Not at the relay.
If the lights are on constantly dont worry about the BCM its already ready.

your explaination is incorrect...the BCM grounds the fog lamp relay coil,,this then energizes the relay closing contacts that then supply 12volts to the lamps....the other side of the lamps goes directly to ground at all times..


there is no positive ground used here,,,

with the headlamps/park lamps on,,, fog lamp relay coil pin#85 has 12volts,,,when the fog lamps are put on fog lamp relay coil pin#86 is grounded...by the BCM pin #30 goes to the fog lamp fuse,,,,pin#87 goes to the fog lamps...these are the switching contacts