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Thread: Bloody Reverse lights gone...

  1. 28th December 2014, 09:29 PM #1
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    Bloody Reverse lights gone...

    I've been wondering why all of a sudden I have no reverse lights.

    While wiring up my trailer plugs I started testing the feed to identify the correct colours - because the RAVE etm is horrible, but I digress... Anyway, I got that all sorted until I tested the reverse - and got nothing. Checktd the talilights to be sure.... same. nothing.

    Yeah, so no reverse lights. Just what I needed....

    I started chasing the culprit. Seems that the inhibitor switch chose this very moment to poop itself. I'm not real happy about it, but ah, what can you do...

    It's a bugger of a thing to get to, but I did test the feed for power and the switch for conductivity.... confirming my suspicion the reverse switch is open circuit. ...and I'm left wondering if anyone else has had to replace this before, or if it is possible to repair.

    Seems they are quite an expensive little part - which is absurd for what it does.

    Anyone in sydney area able to steer me in the right direction for parts? need this one asap - can't drive without functioning lights.

    cheers
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  2. 28th December 2014, 09:47 PM #2
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    d2dave
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    In your post you also mention that you have no tail lights as well. This should have nothing to do with the inhibitor switch.

    If it was me I would be concentrating on the tail lights first, then worry about the reverse lights, as it can be driven without these.
    Dave.

    I was asked " Is it ignorance or apathy?" I replied "I don't know and I don't care."


    1983 RR gone (wish I kept it)
    1996 TDI ES.
    2003 TD5 HSE
    1987 Isuzu County
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  3. 29th December 2014, 07:56 AM #3
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    Sorry, that was my poorly worded attempt to describe the testing of the trailer plug.

    All lights are working perfectly on the vehicle except reverse lights.

    All outputs to the trailer plugs (I have wired two in) are working fine, except the reverse.

    Initially I suspected that I may have blown a fuse or done something to disturb 22 year old wiring - but further testing of the circuit and examination of the RAVE ETM pointed me to the inhibitor switch - something I'm familiar with on The merc, having done a few auto-manual swaps and replacing inhibitor switches & circuitry.

    So when I actually found the little bugger on the front of the trans I was almost convinced it was a pressure switch of some kind and not actually a 'normal' rotating multiple pole switch (like the later XYZ type, which is pretty much the same as Mercedes 722.3xx/4xx/5xx transmissions pre e-gear).

    I put the car in reverse turned the ignition to position 2 and (handbrake on of course) got underneath & pulled the 4 pin connector. I tested for conductivity on the connector and got nothing on any pins, then tested the feed harness and got beeps from the fluke - it's in such a bugger of a position to get to that plug.

    So having identified that I have power to the inhibitor switch, and the circuit will close with a test lamp, the only conclusion I can draw is that the switch has chosen this moment to go kaput.

    Can they be repaired, or is it a case of shell out an absurd amount of $$$ for a switch and 'be happy and welcome to owning a Range Rover' ???
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  4. 29th December 2014, 08:15 AM #4
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    Is the trailer plug actually wired for reverse. Majority are not.
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  5. 29th December 2014, 09:13 AM #5
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    Trailer plugs are not normally wired for reverse. There are four pins needed for lighting, one foe earth and the other two are for electric brakes and aux power for 12 volt caravan lights.

    So unless someone has done something bodgy, I would say it is just a coincidence.
    Dave.

    I was asked " Is it ignorance or apathy?" I replied "I don't know and I don't care."


    1983 RR gone (wish I kept it)
    1996 TDI ES.
    2003 TD5 HSE
    1987 Isuzu County
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  6. 29th December 2014, 05:51 PM #6
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    RRC Trailer harness wiring pinout / schematic

    This probably belongs in its' own thread as there is no specific information (hence this post) for RRC trailer plug harness connector pinouts on the forum)

    Posting this as the issue for my reverse lights is definitely the inhibitor switch on the ZF auto, which has gone belly-up just an a coincidental moment (and annoying one!)

    7 pin plugs make use of the 'service brake' feed on the X172 plug - which is basically a feed from the brake light switch, designed to go to the EBC (electronic brake controller) input

    Note: the 'Service Brake' feed (blue wire on 7 pin standard plugs) requires a separate feed from the EBC for the pin to work correctly as intended.

    Note I did not fit a 12 pin plug - there is no need for me to do this in my application, however the RRC does have provision for most of the connections in a 12 pin plug, with the exception of service brake / EBC signal.

    Page 666 of RAVE shows the X172 Trailer auxillary socket, coupled with two flyleads capped with water proof plugs - C424 (reverse feed) and C425 (+12v Battery)

    With that in mind, the following outputs are available from X172 connector & 2 tails
    Code:
    X172 connector:
RO (Red/orange trace)        pin 1      C400 - RH lamp (tailight) & sidemarker
GP (green/purple trace)      pin 2      C400 - Stop Lamps (brake)
GW (green/wite trace)        pin 3      C400 - RH indicator
GR (green/red trace)         pin 4      C400 - LH indicator
B  (Black)                   pin 5      C400 - GND (earth)
RY (Red/yellow trace)        pin 6      C400 - Fog Lamp- rear
RB (Red/Black trace)         pin 7      C400 - LH lamp (tailight) & Sidemarker

GN (Green/Brown trace)         tail     C424 - Reverse lamp
PW (Purple/White trace)        tail     C425 - +12v (battery - permanent)



How the 7 pin plug is wired:

7 pin socket   		|  		X172 connector
Y (Yellow)      pin 1   ->		GR 	(pin 4)
B (Black)	pin 2	->		GN 	(tail C424)
W (white)	pin 3	->		B	(pin 5)
G (Green)	pin 4	->		GW	(pin 3)
B (Blue)	pin 5	->		<Connected to EBC unit output - input to EBC is from GP (pin 2) or tapped from brake switch under dash>
R (Red)		pin 6 	->		GP	(pin 2)
N (Brown)	pin 7	->		RO/RB (pin 1 & pin 7)

    If anyone is wishing to install a straight 7 pin or 12 pin plug, then I would refer them simply to this url ExplorOZ Trailer wiring diagrams

    it also contains information on the types of plugs and their different pinouts (e.g. heavy duty plugs vs standard)
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