Fixing interior lights in a convertible.

[Toophless]

Disclaimer: I'm only halfway done but when I'm finished I'll post pics and complete instructions to bypass the body control module with a relay if your interior lights stop working.

I picked up a '98 Convertible T/A a while back and the domes haven't worked since I've owned it so I finally got to work on it this afternoon. The radio turns off when the doors are opened so the switches are good and the BCM is at least doing something right, but something in the BCM isn't tripping the ground to the white wire on its largest plug.

From the passenger door I traced the switch in the latch to the BCM. This is a black wire with a white stripe that runs to the BCM's largest plug. I ran out of daylight before I realized the drivers side is a separate circuit (as they usually are in most cars). The switch circuit traced good through the board until I got to the main chip. I was hoping to find a bad surface mount relay on the BCM but there was no action at any of the coils... so that's when I switched gears and decided to just bypass it with a standard 12v Bosch style relay.

I t-tapped the black with a white stripe to one side of the Bosch relay coil, other side of the coil to 12v (contacts 85 and 86 on the relay, either way works) . I cut loose the dome-light white wire from the BCM to keep from feeding a ground back into the BCM system. I could have diode isolated that, but figured it wasn't doing anything anyway, so why bother. The dome-light white wire goes to common (30) and a body ground goes to normally open (87) (again, either way works).

If the weather is good I'll track down the driver's door trigger tomorrow, diode isolate it from the passenger door, and tap the same relay I'm already using. I'll get pictures and try to draw up a simple schematic if I get extra energetic about it.

Sorry if this is a repeat post. I haven't found anything on it here using the search.

Unrelated:
If anyone is interested, I've also tapped one of my radiator fans with a switch to keep from overheating at the auto-cross. It's a simple toggle to ground and a diode to isolate the ECU from throwing a code. Once I get a tune, way off in the future, I'll have the trigger temps lowered.... in the mean time, this is a $5 fix.

[Toophless]

Oh, I'll also take a shot at integrating the dimmer switch, as in the up position, the lights also don't turn on like they should.

[Toophless]

Ok. So for the trigger wires you are looking for pins 7, 11 and 12. 7 is gray to the dimmer switch, 11 is gray with a black stripe to the driver's door. 12 is Black with a white stripe to the passenger door.

Pin 1 is the white wire that needs to feed ground to the domes.

Pictures probably won't help as it is a convoluted mess... so I'll work on a little schematic and see if a newb to LS1.com can post images.

Hope this might help someone some day.

[Toophless]

Simple schematic.