308 registration lamp failure

[randomandy]

The 308 has gone through another MOT (13 years and 200,000 miles old) but has the following minor defect listed:

Nearside Rear Registration plate lamp inoperative in the case of multiple lamps or light sources (4.7.1 (b) (i))

Are the two rear registration plate lamps not just wired in parallel and therefore anything that affects one affects the other - not withstanding issues in individual wiring or bulb holder?

Is this something that could take days to track down? Would I be better off getting a specialist auto-electrician to look at it?

-Andy.

[myglaren]

Take them to bits and see. Could be corrosion in the connectors or the bulb holder, presuming the bulbs are OK.

[randomandy]

Yup, the bulbs are both OK as I swapped them yesterday as they had both blown. They were OK when I tested it when I had the sidelights and headlights on at the same time.

-Andy.

[kingjafad]

Yup, the bulbs are both OK as I swapped them yesterday as they had both blown. They were OK when I tested it when I had the sidelights and headlights on at the same time.

-Andy.

Are you saying the registration plate lights only work when the sidelights or headlights are on? I would assume thats how they are supposed to be? If you have a multimeter, check the voltage across the bulb holders, but i suspect you have already fixed the advisory without even realising it.