Got a weird issue with the marker lights on my 2001 Corvette. The marker lights (side and tail), dash lights, and button lights won't work. All of the other lights seem to work just fine. If I slowly turn the multifunction switch to turn the headlights on, I can get the marker lights to turn on by turning the headlight **** about 1/2 way between the off setting and the marker lamp setting, and the lights come on and will stay on as long as I hold it there. But the moment I go past that, the marker lights cut off.. Obviously the path the signal takes at some point is fine, and the signal is getting where it needs to go. The relay is working, I've swapped it out with the AC relay, and both still work. The fuse is fine, otherwise the lights wouldn't light up at all, plus I physically checked it.. Originally, I thought it had to be a problem with the multifunction switch itself, but after trying 2 other switches, one supposedly tested good via an e-bay seller, a second that was advertised as new (old stock, came in ACDelco box and it still had the plastic sleeve over the handle), and then, taking my switch apart and "adjusting/cleaning" the contacts. All 3 switches are having the exact same issues, I'm seriously doubting it's the switch (How bad can my luck be? 2 of them I haven't messed with), but everything else seems fine... What am I missing? Any thoughts on why the switch would operate while partially turned and then stop the moment it fully clicks in to position?

 

So both the left and right rear and front side markers, all tail lights, and then the dash and the DIC buttons are not lighting ??...what happens if you use the FOB to unlock the doors...do all those lights and the rest come on ??...license plate, back up etc...which relay are you referring to...the ALC Park Lamp relay #43 ??…first pic is the electrical path using the FOB and 2nd is using the switch.

 

Yes, that is correct, none of those lights are lighting up when I use the headlight switch.

When I use the key fob, all of those lights come on.

I've been through three different switches now though. It's rather hard to imagine that all 3 MF switches are bad.

 

Maybe try to disconnect the connector…I believe it’s C207 and see if you have 12 volts on pin Z (orange wire) and then apply 12 volts to pin R the brown wire and see if the lights work ??..also with an ohm meter see if you have continuity between Z and R when you turn the light switch on either in park or headlights on position.

 

Done the jumper thing between orange and brown. All of the lights come on, and the chime starts dinging. What gets screwy, is when I turn the switch from the "off" position, to the "park" or "headlights" position, all of those lights shut off again, even while leaving the jumper in place. If I turn the switch back to "off", the lights come back on. If I remove the jumper, I get nothing. Ideally, that tells me that the switch is bad, I get that, but after 3 switches, I'm wondering if I'm just cursed....

 

Recently I went through 4 O2 sensors before I found one that worked…LOL !!…did you ohm out the switch and see if you have continuity in the park and headlight positions ??…did you jump the 2 wires with the connector connected or unplugged ??

 

There is a 0% chance you’ve had that many bad multi function switches.

i would first start by tightening both of your battery terminals. Sounds simple, but crucial. I would even unhook your battery completely over night and rebook it up tightly in the morning. These cars have a way of resetting themselves.

do you have twilight? Try bypassing the stalk by using twilight and seeing what happens. This is an easy way to eliminate a bad mfs.

next, check your main grounds. Any corrosion? Also crucial.

 

I checked the resistance on the switch, showed OL in off, and 40 ohms in park and headlights. I jumped the 2 wires with the connector plugged in, and on the switch side.

Perhaps it is yet another bad switch despite one being "tested good" and the other being "new"... Any idea where I can get a good one? I've been searching e-bay because everyone seems to be sold out of them.

(Edited because I made a dumb)

 

Should show OL with the switch in the off position but in the park and headlight position there should be continuity !!..with lights working with the FOB that’s telling me the grounds for those lights are fine…as you can see in the wiring diagram the electrical path goes through the relay and the coil side of the relay is being energized by the ALC relay at the BCM.

 

Should show OL with the switch in the off position but in the park and headlight position there should be continuity !!

 

Wait, no, sorry, typed that out wrong. showed OL in OFF, and then about 40 ohms in park and headlights on.... Been a bit of a frustrating day trying to figure this out. I get what the schematic is saying as far as how it's wired, it's just for whatever reason that doesn't seem to be how it's actually working at the moment for whatever reason... And the same problem on 3 switches is really aggravating as well....