DRLs never have worked since i got the car. Today i took the cluster shroud off n checked out the headlight switch. “Looks” fine. Went to the driver fuse box, noticed that the 15a that i assumed was in illum spot was actually just in a spare spot , and that illum was actually empty?! So, swap from spare to where it’s supposed to be, and suddenly the Drls work on battery. Then turned lights off. Put everything back together. Start the car, get going, and turn DRLs on. Car shuts off. Fuse not blown. Short? Bad ground?

 

Bump

 

Try posting a video

 

DRL = Daytime Running Lights?

the FC doesn't have those, so i'm confused

 

I think he's referring to the front + side marker lights and tail lights.

Unless he's in a market that got FCs with DRLs.

 

Wondrous bread is correct. And i don’t know how a video would help here? It’d just be a running car with no taillights or a non-running car with taillights.

 

I've had weird issues with DRL's before, but never where the car would shut down when you turn the headlight **** one click. . .Cause that's when the DRL's come on right?

In my cases, they always went back to the flasher control module or the headlamp switch.

The headlamp switch gets connected to a short cable which then plugs into the main harness. Early S4's had a tendency to short out at the connector on the back of the headlamp switch. . .burns the receptacle and plug. . . ..I've had to go through this particular problem twice.. . .. . . The connector starts to turn brown from heat damage caused by the short.. . .The failure was I had no taillights or DRL's but I could get high beams to work.

Another time the DRL's did weird flashing things because the flasher control module failed.

The age of the car means all connections/plugs need to get removed and replugged into the device it serves. . . .My warning indicator lights won't work sometimes because the plug going into the back is wonky and age corroded/tarnished. I need to clean the pins. . . . Pay particular attention to electrical connections at the plugs/pins if you see no obvious signs of shorts.

But again, you're saying it shuts the car off. . .. . Not many things do that. . .Anything that interrupts ignition or timing would cause a car shut down while running.

 

Yes, this happens at one click. I failed to see if full headlights also caused this while the illum fuse is in place. But for sure, “DRLs”/marker lights fuse/switch is causing the full shut-off.
I’m not near my car right now, but is there another plug AT the main harness from the headlight switch? Headlight switch plug had no signs of overheating or even corrosion on plug prongs. I Started to try and disassemble the switch but i can’t find a good how-to, don’t wanna snap any of this 40y/o plastic or screwup the pcb.

 

The Canadian cars did. This why even the base model S5’s had fog light- I guess was cheaper than to light them up for DRLs (which kicked in as a requirement in 1989) than it was to fiddle with the circuitry to use the pop-ups.

Canadian cars are little different. For example, S4’s and S5’s all have driver and passenger mounted mechanical slides mounted individually to each of the side vents to allow circulated air, or air drawn for the cowl. So you can still bypass the air recirc if it was engaged. No idea why.
Cdn cars also never had the awful S5 retracting seatbelts, which was nice.
We had a S5 base model, addressed as the GX, which had black interior, head lights, power steering, and sometimes air conditioning. No power anything, and no sunroof. It came with 5 Lug 15” stamped steel wheels with single pot pistons at all 4 corners.
Some of the S5’s came with the headlight washers nozzles.

 

Update: only fuel is getting cut when i have the illum fuse in place and turn on taillights.

Normally without the fuse, i can drive fine w/ headlights,brake,signals,reverse lights.
With the fuse, even if i skip DRLs/taillights and turn it fully to headlights, it won’t start. Just cranks.



2nd update: it’s not the fuse. Without the illum fuse in place, I took the headlight switch plug out and jumpered individual lines. Turn on my dash lights, my taillights, headlights, h/l motors up/down.
i turn over the motor, touch headlights, engine stays on. Touch taillights, engine shuts off. Wtffffff.

so basically, it’s not my fuse, nor my headlight switch. Why would taillights be connected to fuel or maybe ignition? I do have problems with my ignition switch as it is.

 

the fuel pump power goes through the ignition switch

 

Does that mean the ign switch is getting shorted by the illum fuse? Or even w/o the fuse, it gets shorted by the taillight wire?

 

the lighting circuit is separate from the fuel pump circuit.