No Tail lights on Passenger Side - SOLVED

[emerydc8]

Moderator edit: Root cause was a defective bulb-out monitor / module, see post #5 below.

I measured the voltage at the six-pin rectangular tail light plug for the two bulbs on the passenger side that should normally be illuminated with the headlight switch on and both are indicating 1.4v. I thought it might be a bad ground so I put one probe of the voltmeter directly on the screw going into the body. That screw attaches the tan ground wire going to one of the pins on the six-pin plug, so this should rule out a bad ground. I verified the screw is making a good ground. The two bulbs on the left side illuminate as they should. I swapped the bulb-out monitor behind the fuse box but still no change. I have an additional monitor I will try next and another on the way from eBay.

On the right side, I’m not getting any voltage on the other pins at all although I didn’t check yet with the brake pedal depressed or in reverse. Maybe I have two bad bulb-out monitors but I think it’s unlikely. I can’t tell from the wiring diagrams but does anyone know if current to the right side tail lights is just tapped in parallel from the same bulbs on the left (other than turn signals of course) or is the right side power sent directly by wire from the bulb-out monitor for each individual side? I guess I’ll have to start unwrapping wire bundles below the left tail light as I trace the problem upstream. I took the inner trim panel off at the lower back of the trunk so I can see the wires running across to the right side tail light and they don’t appear to be damaged.

Any thoughts? A bad headlight switch couldn’t cause this, right?

 

[doolar]

I would absolutely suspect the headlight switch. At least the Euro ones control each side separately, and can potentially fail like this, not that I’ve experienced it myself.

 

[emerydc8]

Thanks. I have two on order. IIRC the headlight switch—like the ignition switch—can cause weird things to happen when it goes bad.

 

[emerydc8]

[UPDATE]

Just a follow-up: I replaced the headlight switch but the problem persisted. I decided to try the third bulb-out monitor I bought on eBay and now both lights that were out on the right rear side are working. But now the side/tail light on the left is not. I checked the voltage and all I'm getting is 1.4v. I guess I'll keep trying monitors until I find one that works. At least this keeps me from getting pulled over.

 

[emerydc8]

I would absolutely suspect the headlight switch. At least the Euro ones control each side separately, and can potentially fail like this, not that I’ve experienced it myself.

Those headlight switches are impressive compared to a domestic auto. The pictures speak for themselves.

Installed a 4th bulb-out monitor last night and all lights are now working.

 

[gsxr]

Jon, to confirm, you had THREE defective bulb-out modules? All is well with the 4th try?

 

[emerydc8]

Correct.

 

[Sebastopol]

I was chasing a bulb out right rear tail light for a year. The volts were 10.5 to 11.1. Ground was good, all other light sockets at full voltage. Finaly solved the issue - replacing the relay (bulb-out / bulb-monitoring) module in the fuse box. 126-542-03-32. (GSXR edit: This part number is for non-USA / ROW models.)

Light is bright and solid.

 

[Sebastopol]

I was chasing a bulb out right rear tail light for a year. The volts were 10.5 to 11.1. Ground was good, all other light sockets at full voltage. Finaly solved the issue - replacing the relay module in the fuse box. 126-542-03-32.

Light is bright and solid.