Interior light wiring help needed. Missing 12V.

[Anil]

Hello All

I'm hoping someone can help diagnose the interior lights on my '88 3.2 Carrera.

The clock and glove box light, which run off the same 5A fuse, are working fine but both interior light fittings do not seem to have a 12V supply available via the black wire.

There is continuity between both black wires for each interior light, but not to the 12V supply to the clock or glovebox light. I have also confirmed that neither black wire is shorting to ground.

Note that both door switches appear to be working fine, in that the brown/white wire to the interior light is being grounded when the door is opened, but without the 12V supply these lights will never work.

The Bentley manual I have doesn't seem to cover the interior light wiring, so I have copied a page from the factory manual as originally posted on Pelican.

 

In order to confirm why the 12V is missing to the light fittings, does anyone have a picture of how the interior light wiring is routed down the A-pillar and through to the front trunk area on a RHD car? Hopefully, I can then trace the wiring to a specific connector that supplies the clock/glovebox light.

 

 

[Stellify]

When you are talking about the interior lights I assume that you are talking about the dome lights above each door, and that the car is a coupe?

From memory I think these interior lights can be 'tilted' to turn them on, off or have them come on when the door is opened. Some time ago I was caught out thinking that I had a fault with the wiring and it turned out that I had unknowingly tilted the light to the off position, tilting it back "fixed" it, or it could be a fault in the tilt mechanism within the light?

Regards

Mark

 

[Jonny Hart]

Pretty sure you can see the wiring disappearing up the a pillar under the dash on the RHS of the car.

[apesman]

Off side, behind dials there is a multi spade connector feeding interior lights up the pillar as Jonny said, check there for dodgy connection. it also feeds bonnet light.

[Zohar]

On a mildly related note, any idea how I can track the earth wire for this circuit the goes into the a pillar and connects to the (rhs) driver side door light switch? 

[Anil]

Thanks for the suggestions.

Just to round this off, I eventually found the connector to the interior/dome lights.

On my 88 Coupe, the connector was located in a bunch of wiring just behind the front boot hinge on the nearside/passenger side.

The wiring then routes up the passenger side A-pillar to the interior/dome light.

In my case, the 12V wire had an internal break around 4 inches from the connection on the passenger side light and only registered a voltage when wriggled about. So no 12V to either light.

I had to unpick the cabling/insulation away from the sunroof loom in the trunk area which allowed me to pull it through the interior light aperture a little more.

I then cut the wire up to the broken section and fitted a new spade connector.

Everything now working fine.

Also installed new Philips 1W rated LED warm white festoon bulbs which are usefully brighter than the standard 10W bulbs.

 

Zohar - Are your interior/dome lights working when set to the ON position, but don't work when opening the doors? 

[Zohar]

Hi Anil 

the lights both work manually , but did not work with the door switches. I fixed the passenger side ( bad contacts - cleaned and re soldered. ) the driver side wire broke and fell into the door. Tried a hook but no luck. Would like to find its origin , pull out and re route.