Reverse lights/demister relay no-go

[Porkchop]

Slowly working through all the niggling faults on my 84' 240 estate and am yet to nail a couple of them and would appreciate any feedback I can get. We haven't had reverse lights for a very long time, long story short, we are on our third gearbox having destroyed a couple of them slogging trailer loads of fill up our winding gravel driveway. We no longer deal with the mechanic that did the job(s) so I can't ask him but each time we have had a gearbox swap the reverse lights remain non-working (despite having asked him to investigate). As far as I can see the wiring is going where it ought to go and I can't believe that the switch has been a dud on all three gearboxes.
I suddenly had an epiphany yesterday when I realised that perhaps the relay has developed a fault as on the fuse compartment listing No 12 fuse services both reverse lights AND rear demister (neither of which have worked for ages). After several fruitless hours spent trying to track down the relay location under the dash I used a test light on the demister at the tailgate loom and found I definitely have power, there are a couple of small breaks in the element grid that I hadn't spotted before that must be causing the issue. I still haven't had any joy on the reverse light situation and would greatly appreciate any input from forum members who have had similar issues....

[CaptainAhab]

If you gave had a couple of gearbox changes it's possible the switch wiring has not been reconnected to the wiring loom. The wires (two bullet connectors) come off the back of the switch (located on top of the box) and up through the hole in the floor for the gearstick. Take the rubber gaiter off and you should see it going off under the carpet. There's a plug in there somewhere up near the base of the centre console that would be worth a check.

Cheers,

Cap

[Porkchop]

Originally Posted by CaptainAhab

If you gave had a couple of gearbox changes it's possible the switch wiring has not been reconnected to the wiring loom.
Cheers,

Cap

Good point, I had a lot of woes with the OD not working a while back and traced it back to a faulty relay (hidden behind the centre vents on dash), I re-soldered all the cracked solder joins on the CB and got it working again something our erstwhile mechanic had failed to either trace or rectify. In the process of doing that I pulled the gaiter a number of times and checked and replaced where necessary the wiring associated with the gear knob switch including the earth connection etc etc. I could go out and order a new gearbox switch and eliminate that I guess but it doesn't add up to me as the three gearboxes it's had have all had their switches in-situ when replaced AFAIK so it seems unlikely all three have been duff.
I'm still a bit mystified by the location of the relay that apparently resides on this circuit. This was a vehicle intended for the Australian market so some of the US-based electrical schematics don't tally up exactly, is there any way of checking the operation of the reverse light and switch (can I hook up a test light directly to the switch for example and shift it into reverse?) cheers, Ian

[CaptainAhab]

The easiest way to check the switch operation is to use a test lamp or a continuity tester. Just stick the car in reverse and bridge the contacts.

Not sure what setup you guys run but the schematic for an 84 (Articles section, wiring diagram link, 1984 model, page 4, top left) doesn't show a relay for these lights.

Good luck!

[Porkchop]

I take your point Cap'n, I think the US-based models do show a relay in some schematics (certainly for the Rear Demist) but also the fuse panel cover shows for fuse 12: "Back-up Lamps (Relay, Power Windows) (Heated Seat) (Air Cond) (Relay, Rear Demist) and I've probably misread the information!

[Porkchop]

OK, Just finished a heap of work on the Estate, replaced the two lower front ball joints (old ones were absolutely cream-crackered), welded up the broken exhaust bracket that goes to the bell housing and replaced missing lock nuts and bolts etc. And then comes the reverse lights situation, had a good old poke around and managed to rig up a small mirror to confirm my fears-no wiring or plug to the gearbox-mounted switch!! Little wonder I wasn't getting any joy, I found the wiring to the switch had been tucked away under the carpet minus the plug and double-checked the wiring colours which nailed it.
A quick rethink and I crimped on some bullet connectors http://www.hella.co.nz/en/products/a...le-bullet.html and lo and behold reverse lights functioning after years of inactivity! I'll track down a loom and attached plug from an associate here in Oz and replace the connectors if they fail/drop off but at this stage of the game I'm a happy camper....