Thread: horn and interior light not working on 78 range rover

I guess I would look at the wires in the steering column shroud.
Seeing they have different earths then it should be the power side.
Trace the wires from the slide interior light switch and you may find it goes into a bullet connector shared with the horn and the power side has fallen out.
It may of course be a coincidence and the interior llight fault is caused by one of the door switches not grounding or the wire falling of the door switch, so check them.

A quick check with a meter or test light at the interior light will narrow down if it is a power issue, or earthing issue. You should have a constant 12 volts at the interior light, as the ground at the door switches is what turns it on and off. Follow PhilipA's advise on either side depending on what you find.

Cheers - Gav.

T-Shirt - Lucas Prince Of Darkness - T-shirts, Hats, Clothing & Gear for Land Rover Enthusiasts says it all...

My rear door windows sometimes work, sometimes not (as a pair) and the self-dimming mirror / map lights have a loose earth or power connection somewhere and works only if you wriggle it...

The LH front door lock actuator does'nt always actuate.

- But is'nt that "normal" for Lucas switch-gear and connectors ?

cheers,

James who worked with German and Swiss machinery all his working life...