Dome and Door Courtesy lights not coming on with front passenger door (2007 Sedan)

I removed the switch and replaced it with one I knew was functioning, but it turns out that switch must be good. . It works in the door I swapped it to, but the problem door still doesn't work, with either switch.

Nope; I checked it against the other doors - I register a little under 12v at the other jamb switches and bulb sockets - but neither the jamb or the door light has power on the problem door.

Possibly. The wire runs inside the (B?) Pillar - the one directly between the doors, and then downward toward the frame. I'm not sure where it goes from there.

I own a multimeter; will I need another tool to trace this wire?

Would it make sense to check another position or two in the car? .I am told that other than loose connections or breaks, there is a Multiplex ICU in the fuse box which can be the problem.

Thanks for all your help. I am not positive that I am performing the trace correctly, but had a tough time searching for the technique. Could you describe (or send me a link re:) using this multimeter to trace a wire within the car?

I am using a GE 2524 Digital

This single wire coming from the door jamb quickly joins a heavy bundle that goes down into the side sill, and then branches into three complex-looking arteries that head left toward the driver door. It appears highly protected.

I tried to test for Ohms at that switch and at the light socket - I was able to get results from the functioning doors, but from the problem door neither from the socket or the switch did I register Ohms.

According to the wiring diagram, there are only three wires involved in that door's lighting:
> A single green/red from the problem door's jamb switch to the Multiplex ICU, grounded with the switch.
> A hot white/blue wire from the fuse to the light socket, and then a yellow/green wire from the socket to the MICU

Kindof like this:
[fuse]--white/blue--(bulb)---yellow/green---[MICU]---green/red--[switch+ground]

If the lights are all connected directly to the fuse, should that light socket have power even if the door switch doesn't? Would grounding the white/blue wire cause the light to come on, if that were the case?

I am wondering if power to the door switch might actually be dependent on the light socket's connection.

Ok. Yes, the meter is one of those $10 yellow models from Walmart, but it does detect DC current.