Ron Barnett

My 2004 has recently had unusual reactions when I try to drive with my fog lights only - sometimes it works normally but sometimes when I turn only the fog lights on the headlights pop up. This doesn[t happen every time I try to turn the fog lights on, sometime they work normally. My mechanic said he suspected a body control module was at fault and recommended that I take it to a dealer. Nothing against Chevy dealers bt I generally try to avoid dealerships when possible. Has anyone else ever had this problem and, if so, how did you resolve it?

craig-o

Sorry to hear about that. Just a couple things to clarify that they are NOT working as designed:
The headlight switch on the stalk has 2 "on" positions: #1 parking lights and #2 headlights. The fog light switch is mounted on the dash, and is a separate switch. If you turn the headlight switch to the 1st position (parking lights) the fog light switch is energized, allowing you to turn on the fog lights without the headlights popping up. If you turn the headlight switch to position #2 (headlights), this will cause the headlights to pop up, the headlights to illuminate, and the fog light switch is still energized. If you turn the headlight switch from position #2, back to position #1 (without first turning it to "off") when the fog lights are on, the fog lights will stay on, the headlights will stay UP, but the headlights will NOT be illuminated.

If the headlights are intermittently popping up when the stalk switch is only in position #1, that is not functioning as designed. I would guess a new multi-function stalk is the most likely candidate.

GCG

Speedy007

Wrong the switch has 5 settings. Off/parking lights/headlight/headlight open light off parking light on/ off & close lids

Speedy007

Either way when your using fog light your tripping your headlight switch somehow one would only assume it was wired together inside to make one of them operate due to a fault somewhere else in the switch wiring and or mechanism/ or head light unit motors connection to the fog light possible was wired wrong somewhere I would check fog light wires/headlight and under the dash inside ! And go from there

GCG

The Post from @craig-o wrong?... Really?... Let's see...

I would say that both of you are saying exactly the same thing, but since you want to nitpick... I just took the liberty of rearranging the pertinent paragraphs in bullets, so it's easier to see.

You state that the "switch has 5 settings". In your list 1 and 5 are the same, so that would actually reduce it to 4. But the physical switch in that portion of the MFS doesn't even have 4 possible positions, it has only 3:

1. OFF
2. Parking Lights
3. Headlights

Now, how the switch is operated yields 4 possible results: everything OFF and closed, plus the 3 items listed under "Operation" in craig-o's post, or items 2 to 4 in your list.

Craig-o omitted to mention that when the switch is moved from "OFF" to "Parking Lights" and from "Headlights" to "Parking Lights", the Parking Lights are turned ON but I guess that's pretty self-explanatory.

Again, where's the misinformation?


Yes, those symptoms point to the MFS as the most probable cause.