I recently acquired a 1974 series 3. The switch on the left top in photo does not work. When I toggle it, it feels loose as if it is not connected to anything. However, when I toggle the headlight switch next to it to the middle or on position, the dashboard lights come on, illuminating the gauges. Is it possible that a previous owner wired it so that the interior lights just run through the headlight switch so that the interior lighting switch is redundant? It is a soft top so there is no dome light. It is a military version and I do know it was rewired from 24 V to 12 V.

 

Mine was a 2A so not necessarily the same. IIRC my dash lights had a switch of its own, not through the headlight switch. Do you have the wiring diagram? It's a very simple system and won't be difficult to trace.

 

Your description sounds correct.

The top left switch is supposed to operate the gauge backlighting, and the top right is supposed to operate the running lights in first position and headlights in second position.

Given you say the left switch feels 'loose,' maybe it failed and a previous owner moved that circuit over to the headlight switch.

The two screws on the face of the binnacle are all that is needed to remove the whole assembly. Switches are available at the usual LR parts outlets if you decide to wire it back correctly.