No reverse lights with low voltage

[andyg plym]

So haven't had reverse lights for years !
Replaced the switch and still no good, checked the wiring in the gaitor to the tailgate and all appears well, i checked for voltage from the blue and red feed but it only reads 0.05 volts, anyone had this before?

I have peeled back the wire as far as I can but there are no visible breaks or stretches

Cheers

[Tonybolony]

Sounds like you've done the most obvious first things.
To take it a bit further- with Ign on, and in reverse (Soz to state the obvious) meter from Rev Light Live to an Earth from another working light. If still no reading- check the Live from the other working Light (Must be ON) to the Earth of your Rev Light.
Whichever test comes up with no voltage shows where the fault is.

One more step- set your DMM to Continuity, and with No lights on, and lamps (bulbs) removed, check for continuity between earths on both these lampholders.

If not conclusive, check for 12v (ish) from Rev Light Switch on 'box (if you can reach it!) with Ign on, and in reverse- to a known, clean earth. (Both sides of switch if you can).

If all tests at rear lights are good, and 12v available on Input and Output of Rev Light Switch- assume cabling fault from 'box to Rev Lights. (Worthwhile trying a Test Lamp directly to clean earth from Rev Light Switch output, as a Load- it's possible to get a good reading with a DMM across switch, but it could break down when load applied.

Good Luck

[Tonybolony]

Or you could always do what we used to do back in the 70's - bolt a single spotlight to the rear bumper, and Hey Presto- You've just turned into The Stig

[UrS4boy]

B4 Avant Reverse Light Wiring Details

So haven't had reverse lights for years !

These (from S2Central's stash) might help you:

Relay (J226 - not sure where it lives)


Fuse 12 in the fuse box under the bonnet:


Fuse 12 connections (note the thin line "a" running to the right of the diagram):


Here that "a" line runs to "B15a" where it spilts. One branch goes to the F76 MFTS (a clue if you were having problems with it) and the other, to the F4 reversing switch as a black wire (see more switch details of that below the wiring diagram). From the F4 reversing switch, it runs as a Blue/Red wire through a couple of connectors (one (T8e) in the engine compartment and the other (T6b) in the left of the boot). Finally it reaches the two reversing lamps, M16 and M17, the sockets of which are grounded (earthed) via brown wires at two positions in the tailgate wiring loom (something to check).



The brass and black plastic two-pin reversing switch (presumably on hot black wire coming in and then the switched blue/red wire coming out):



Hope that helps

[andyg plym]

Food for thought dave, fuse is fine but mfts wiring ain't great, I bodged in recently a new section of wiring in that area until a complete aux loom comes up for sale.
Odd how it's 0.05 volts though

[UrS4boy]

Food for thought back at you: If your avant is/was equipped for towing, the towing package reverse light relay (position 19 in the auxiliary relay panel under the rear seat) might be fubar'd, i.e. stuck thinking that there is still a trailer plugged in to the avant and therefore, no reverse lights are appropriate.



This is the J269 in this diagram:

[UrS4boy]

OOps. Brain fade. That J269 is for the rear FOG lights, not reversing lights.

Carry on. Nothing to see here.