I have looked through the reversing light threads, including my own ! But can't find an answer.

I have a 1999 Mk2 Mondeo, the reversing lights stopped working about this time last year, typical dark nights !

Following forum advice I took switch out from Gearbox, cleaned and replaced. It worked for a while, went intermittent, then stopped.

Tried that again with no luck this time. If I take switch out and press the ball bearing the lights work, so I know the circuit is OK.

I am guessing it a gearbox issue, so the question I'm getting rounds to, can I rig up a switch from inside the car or do I need to take the wires from the gearbox ?

Thanks, and sorry if that was a ramble.

14 minutes ago, Theshed said:

can I rig up a switch from inside the car or do I need to take the wires from the gearbox ?

Yes you can fit a manual switch inside the car to control the reverse lights, BUT to comply with vehicle lighting regulations, there must be a very prominent warning light with the switch so that it is illuminated when ever the reverse lights are on.

Personally I'd buy a new switch for the gearbox and the old one could just simply be worn internally and not making a good enough contact when the reverse gear is selected.

I believe the switch is not expensive but with the lights working quite easily with a press I'm guessing the internal gearbox arm is not lifting up enough ?

Is there anywhere I can pick up a feed in the cabin or do I have to feed through the bulkhead grommet ?

The signal from the gearbox reverse switch is actually sent to the Body Control Module (BCM) which is part of the passenger compartment fuesbox, behind the glovebox. It is the BCM which then sends the 12V positive to the reverse lights.

So you need to connect to the input side of the BCM (the side that gets the signal from the gearbox) so that the power to the reverse lights is still sent via the body control module.

Feeding a 12V positive supply directly on to the reverse lights would mean a positive supply was back fed to the BCM and I'm unsure what the consequences of that would be.

I have found a snippet from the Mondeo wiring diag0ram, from what I can see the circuit goes from the CJB F80 via gearbox switch to BCM /GEMS module connector C428 pin 20.

If I'm correct then I just need to take the feed from F80 via switch/warning light to the BCM pin 20 ?

Ah, but do we know what colour C428 is ?

 

Green 👍

Ok so hopefully, for me, the end of this topic. You may recall I was convinced it was a Gearbox fault as when the little ball on the switch was pushed in the lights illuminated.

I looked at rigging up a switched circuit from the BCM/GEMS module. Although it had the green connector as pictured the actual layout was different.

So rather than risk that module by making a mistake I ordered a new switch.

£8 and half hour later, switch replaced, and lights working ! 😁

Maybe the little ball had worn down over the years, I don't know but we can now see where I've been.  😂

Thanks All.

 

On 11/12/2023 at 7:11 PM, unofix said:

Personally I'd buy a new switch for the gearbox and the old one could just simply be worn internally and not making a good enough contact when the reverse gear is selected.

2 hours ago, Theshed said:

I ordered a new switch.

£8 and half hour later, switch replaced, and lights working ! 😁

Maybe the little ball had worn down over the years, I don't know

Glad you got there in the end 👍