Bizzarely, the interior lights came on when my son was driving home a few days ago. When the car seems to be warm or has been driven for a while they work. When going out to her cold, they don't. I have done nothing to change anything on the vehicle (too cold to work on plastic parts currently). If anyone can think of any reason why they work (and why not when cold starting) I'd be keen to hear.

 

maybe your door jam light plunger is sticking - check it and lubricate if necessary

 

there’s a door jamb light plunger??

I wish it were that simple. Alas the lights weren’t coming on at the switch on the dome light unit. Although they do now… .

 

D2s get the door open/closed signal from the latch assembly itself, not a separate plunger-style door switch.

 

Hmm, that to me sounds like BCU. Did the lights just come on and then time out after 10 sec or so and go off while he was driving? Guessing interior light switch is in the ‘door’ position?

Or -- what?

 

@nashvegas Thanks. The dome lights are slow to come on when the vehicle is cold (and it's cold now in Ontario); they're a bit more lively when the vehicle is warmed up, and they do shut off after about 10 secs. There are also occasions when they don't come on at all. It's very odd.

 

So that means the BCU is capable of activating them, and then the timeout built into the BCU logic is turning them off properly.

Two possibilities:
Seems like maybe solder joints in that BCU?
Or a wiring issue that seems to regain connection in the cold. Ground or +, idk.

It would be interesting to “tap” on the BCU and wiggle all the wires around it when the lights are on, or off, to see what happens. Ie -- does that make them go on or off?

 

I'll give it a go this weekend when I can get to the vehicle. The wiring in the vehicle is in surprisingly good condition. The vehicle is dry as a bone on the interior; no corrosion anywhere, but it could be that solder drying out on a PCB somewhere, or a connection. I'll check. Thanks for the prompt.