Morris Minor Owners Club

Hello, I'm just getting the wiring in for the interior/courtesy light in my 1970 Traveller. See Picture. I'm not convinced by the Earth wire setup. Looking at the wiring diagram it appears there's a black earth wire that runs back from the light, down the windscreen pillar and connects into the loom. On my car, it's a short length of wire that connects to one of the bolts that holds the rear roof to the cab. It doesn't seem very adequate as it goes into two lengths of wood and has rubber in the middle. Have I missed something?

Every Traveller on which I've ever worked has the short wire to a roof bolt. That would be a cost and weight saving compared to running it back to the loom, so I'd stick with that. You need 1 supply wire from fuse box, 1 earth back to a door pillar switch for automatic operation, and 1 short earth wire for manual operation.

thanks very much for the advice

culp wrote: ↑Thu Oct 07, 2021 9:42 am Looking at the wiring diagram it appears there's a black earth wire that runs back from the light, down the windscreen pillar and connects into the loom.

I'm intrigued by the idea of you actually having a wiring diagram that shows such detail.
The only official diagrams I know of are the schematic/hybrid ones in the Manual, I've never seen actual Wiring diagrams that show routing around the car.

Are you referring to a diagram supplied with a new loom you've fitted?



For those who don't know the difference:
A schematic shows the plan and function for an electrical circuit, but is not concerned with the physical layout of the wires.
Wiring diagrams show how the wires are connected and where they should located in the actual device, as well as the physical connections between all the components.

So the ones in the Manual aren't fully 'Wiring Diagrams', they're just enhanced Schematics.

I've got to sort mine out as well. I assumed that after running down the door pillar the wire connected to the door close/open switches so that when either door is opened a connection is made to ground, turning on the light.

The ground connection local to the light may be for the switch on the light itself, i.e. there is always a permanent feed to the light: the source of this feed also supplies a permanent feed to the horn switch. Both the horn and the interior light can operate without the ignition being on.

I seem to recollect that the purple wire is the permanent feed and the brown wire is the door switch ground.

tomb1963 wrote: ↑Sat Oct 09, 2021 10:30 am I've got to sort mine out as well. I assumed that after running down the door pillar the wire connected to the door close/open switches so that when either door is opened a connection is made to ground, turning on the light.

The ground connection local to the light may be for the switch on the light itself, i.e. there is always a permanent feed to the light: the source of this feed also supplies a permanent feed to the horn switch. Both the horn and the interior light can operate without the ignition being on.

I seem to recollect that the purple wire is the permanent feed and the brown wire is the door switch ground.

Almost 100% correct, just depending on car year.

Purple is permanent live to the lamp and it is the Earth that is switched, just as with the horn circuit.

The switched one that goes off to the Door Switched is Brown/Black or Purple/White, depending on the build of the car.
Post 63 the wiring is Purple/White according to the wiring diagrams, so assuming this is a new loom, someone has got that wrong or the wrong loom is being fitted. The Black is shown on the diagrams as having a connector, so that should indicate the Earth is not immediately local to the lamp. If you look at the diagrams, a local earth is shown without a connector, as with the exterior lights. Perhaps they changed to using a local earth but never amended the Manual Diagrams? I'm not convinced the Diagrams are particularly accurate in that regard. standards of the day just weren't that accurate. Drawings and diagrams were often seen as a 'guide' rather than 'instructions'.

But I'm confused as to this diagram Culp speaks of, since the the photo shows the local earth, but he's not been back since Thursday....