Outer Limits 4x4 Board

Hi all,
Recently purchased another GQ, noticed reverse lights dont work, changed bulbs and didnt fix it. Connected my lights to another GQ to check if problem with actual Light fitting....it works on other GQ.
Went back and tested if power is arriving to back when reverse is engaged, its not. And now im stuck. I checked and fuses just in case something was blown, all fine. Brake lights and blinkers all work fine but just not reverse.
Dont know what it could be. Rego in a couple of days so need to fix asap.
Any help would be great. Its a 4.2 Petrol Carby Manual Patrol.
thanks in advance

If the fuse is good, then check the reverse light switch on the gearbox. If you disconnect the connector and bridge the pins with ignition on, the lights should turn on, indicating a faulty switch.

Check output of reverse switch on gearbox.

If the truck does a lot of river crossings or 'water work' the reverse switch on the top of box shorts out and its a bitch to change the switch.
As this circuit is also on the alternator excitation/gauges fuse your alt also stops working and obviously then the batts go flat. (NZ Patrols/Safari's)

So most guys (including myself) leave it disconnected......so maybe thats the reason.
if you need to change the switch - it can be done in place with lots of extensions bars and sacrificing a spanner and socket!

good luck