GreenLove Posted January 12, 2012 Share Posted January 12, 2012 Been trying to figure out why my Defender 110, 1992 reverse light isn't working. I've managed to ascertain the following: - Bulb and holder works - Reverse light earth is fine - Wire from reverse light to engine compartment shows no resistance, so no breaks in the wire. - Reverse switch on top of gearbox replaced and tested. - With reverse gear engaged and ignition on, I'm only getting a reading of 0.3V (taken from engine compartment) I'm thinking that for whatever reason the 0.3V reading is too low, so the wiring going from the engine compartment back to the fuse box needs checking? Does anyone know what the problem might be? Thanks Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted January 12, 2012 Share Posted January 12, 2012 You got the switch wound in far enough? Quote Link to comment Share on other sites More sharing options...
danebrewer Posted January 13, 2012 Share Posted January 13, 2012 may seem stoopid, but have you checked the fuse and holder to see if it's fused/corroded? I've had that a couple of times on my lights... Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted January 13, 2012 Share Posted January 13, 2012 If it is a LT77 then you may never get it working. There is some kind of internal wear and no amount of screwing in the switch or changing bits will ever get it to work. Only cure is a complete top end rebuild of the gearbox shifter. Best just stick a manual switch in the system and be done with. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 13, 2012 Share Posted January 13, 2012 Temporarily bridge out the switch so that it's not involved. If the light then works when the ignition is on, it points to a fault with the switch (so see above), otherwise it's not involved. If that is the case, I'd say have a look also at the connections in the looms; these gave me very similar problems. On a 300tdi these are the multipin plugs and sockets just below the clutch master cylinder on the bulkhead. Check with a meter that you have continuity to earth (through the bulb and bridged switch). On mine I just had to unplug and replug one of the connections to make it work as it had corroded somewhat - I cleaned it and gave it a good spray of Electrolube after that. Nigel Quote Link to comment Share on other sites More sharing options...
GreenLove Posted January 15, 2012 Author Share Posted January 15, 2012 Temporarily bridge out the switch so that it's not involved. If the light then works when the ignition is on, it points to a fault with the switch (so see above), otherwise it's not involved. If that is the case, I'd say have a look also at the connections in the looms; these gave me very similar problems. On a 300tdi these are the multipin plugs and sockets just below the clutch master cylinder on the bulkhead. Check with a meter that you have continuity to earth (through the bulb and bridged switch). On mine I just had to unplug and replug one of the connections to make it work as it had corroded somewhat - I cleaned it and gave it a good spray of Electrolube after that. Nigel Everything checks out fine (bulb holder to engine compartment) except the wiring going from the engine compartment through into the dash, then to wherever (I'm guessing the ignition switch, then to the fuse box, right?) I have part of the dash off at the moment, but I just can't make sense of the tangled mess of wires that are hard to see. Any ideas? Quote Link to comment Share on other sites More sharing options...
GreenLove Posted January 15, 2012 Author Share Posted January 15, 2012 If it is a LT77 then you may never get it working. There is some kind of internal wear and no amount of screwing in the switch or changing bits will ever get it to work. Only cure is a complete top end rebuild of the gearbox shifter. Best just stick a manual switch in the system and be done with. Newly installed switch is fine, tested with meter and working without a hitch. Just the wiring remains. Quote Link to comment Share on other sites More sharing options...
GreenLove Posted January 16, 2012 Author Share Posted January 16, 2012 Her's a pic to further illustrate what I've found so far in the diagnosis: Any info would be most welcome. Quote Link to comment Share on other sites More sharing options...
potato head Posted January 16, 2012 Share Posted January 16, 2012 Do you have 12v at the connection in the engine bay on the cable that comes FROM the switch when reverse is engaged? (From memory the cable goes into a connector and then off into the loom that runs down the chassis) Quote Link to comment Share on other sites More sharing options...
GreenLove Posted January 16, 2012 Author Share Posted January 16, 2012 Do you have 12v at the connection in the engine bay on the cable that comes FROM the switch when reverse is engaged? (From memory the cable goes into a connector and then off into the loom that runs down the chassis) Yes, I have 12V coming FROM the switch when reverse is engaged. But somewhere between that return wire from the switch to the one pictured above there's a break. Also, the ignition and fuse box somehow comes into play, which I'm having trouble understanding. Quote Link to comment Share on other sites More sharing options...
GreenLove Posted January 16, 2012 Author Share Posted January 16, 2012 If I could just find a reverse light circuit diagram for the 110 200Tdi (1992)... Quote Link to comment Share on other sites More sharing options...
western Posted January 16, 2012 Share Posted January 16, 2012 wire through bulkhead goes to/from the fusebox. reverse switch is earthed by it's body screwed into gearbox one wire comes from cab/engine bay, other wire travels to reverse lights & otherside of reverse bulbs are earthed. ther isn't a seperate wiring diagram just for reverse lights, it's part of the vehicle wiring diagram, I can upload a 200tdi diagram if you need it, Quote Link to comment Share on other sites More sharing options...
potato head Posted January 16, 2012 Share Posted January 16, 2012 If you have 12v on the switch return wire (not the one that comes from the bulkhead) then you need to check the next connection. Take off the off side rear light cover inside the landy, (above the wheel arch next to the back door lower hinge) and find the same wire and test again for 12v. This will rule out the loom in the chassis. Ralph, are you sure this reverse switch is earthed through the switch body with it having 2 terminals? Quote Link to comment Share on other sites More sharing options...
western Posted January 16, 2012 Share Posted January 16, 2012 Mine R380 switch has 2 terminals, this one http://www.lrseries....20switch&page=1 IIRC it has a green wire 12v feed to switch/reverse lights & a green/brown trace wire out to rear lights & lights are earthed in rear body corners as are the other rear lights. this is the LT77 reverse light switch, 2 terminals http://www.lrseries....OCK-SWITCH.html Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted January 16, 2012 Share Posted January 16, 2012 Very simple wiring. Ignition on, power to fuse, green wire from fuse via bulkhead to the switch on gearbox (so one side is always live when the ign is on), then green wire from other side of switch (only live when in reverse) back to bulkhead and then through chassis to reversing lamps and from other side of bulb to earth. So pull both wires off the switch and find which one is live when the ignition is on. Reconnect this wire to the switch and put it in reverse and you must now have 12v on the bare terminal. If not then the switch is Fubared. If you have 12 volt on the bare terminal then reconnect it. If you have no reverse lights then run a wire straight from the switch to the reversing lights and check they work OK. If all good then there is a wiring fault somewhere between switch and rear of vehicle. Use continuity tester to find out where the break is. It is either between the switch and the bulkhead connector or else somewhere in the chassis loom. Either way you can easily substitute the broken wire for a new one. Quote Link to comment Share on other sites More sharing options...
bodumatau Posted February 25, 2015 Share Posted February 25, 2015 looking for the part number for the reverse switch for my new R380 I dug this old post up. great to have soon much info at our fingertips!! thanks LR4x4!! Quote Link to comment Share on other sites More sharing options...
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