Reverse lights always on.

[KarlT]

Always something.
Have been messing with electrics (engine conversion) but now the reverse lights are always on if the ignition is on.

Stay on if gearbox switch is connected or not.
Only go out if I remove 10amp fuse or disconnect connector in black box in engine bay.

Has tow-bar wiring but I really haven't touched that bit. Could it be engine loom wired wrong?

[ewenmaclean]

Hello,

it doesn't seem like an earth problem if the right fuse switches it off, but they share their earth with the rear lights - this caused problems for me when they were dirty, but not the same behaviour. What happens when you disconnect the reverse switch from the gearbox?

Ewen

[KarlT]

Cheers for reply.

They still stay on whether loom is connected to gearbox switch or not.

[StuM]

Does the switch, when on, provide the earth for this circuit? If that is shorting somewhere between the swtich and the light, that would cause this I guess..

[ewenmaclean]

Hello,

according to my wiring diagrams, the source goes through the switch and is earthed through the lights... also seems to have some connection to the dual tone horn relay, but I'd think that's not relevant!

How about, for starters, disconnecting the connectors from the reverse switch and seeing if they really do get their power from the right fuse, using a multimeter. Also, with the fuse out, one should have infinite resistance to earth, and the other should have about 4 ohms I think, assuming about 20W per reversing light bulb (if that's reasonable).

Also with the fuse out, what is resistance between these two wires - it should be infinite - if it's not then is it possble they've been squished together somewhere? Otherwise maybe the ignition feed itself in the engine bay is feeding the reverse light or some other loom problem - like you say....

Hope you get it sorted

Ewen

[ewenmaclean]

StuM - according to my diagrams the earth is provided through the earthing points in the engine bay, and the switch provides the live to the lights... is yours different?

[StuM]

StuM - according to my diagrams the earth is provided through the earthing points in the engine bay, and the switch provides the live to the lights... is yours different?

Hey Ewen,

I was just speculating as I don't have access to a wiring diagram/the van at the moment - your post answered my 'out loud thoughts'

Cheers,
Stu

[ewenmaclean]

Hi Stu,

thanks - I'm never how much to trust my Haynes manual on the wiring, and I know things differ according to year and engine etc....

Ewen

(P.S. that's a cool colour your van is )

[StuM]

Yes - I agree, the wiring itself never lies, the Haynes might!

Thanks re. colour

[AngeloEvs]

Did you remove the rear light clusters at any time?

[KarlT]

The rear lights?.....No.

Had another look at them today.
All other lights are working perfectly. Reverse lights worked fine before conversion.

Did remove petrol tank (syncro) during engine conversion so possible for things to have been caught/squashed.
Checked wiring today & wires to switch (gearbox) did look like they had been squashed but I removed coating and the wires themselves looked fine.

I'm going to have to work through this (below) but not had much practise a multi-meter. (much better with a 12v bulb & wire). Any more basic pointers/symbols appreciated..........

Hello,

according to my wiring diagrams, the source goes through the switch and is earthed through the lights... also seems to have some connection to the dual tone horn relay, but I'd think that's not relevant!

How about, for starters, disconnecting the connectors from the reverse switch and seeing if they really do get their power from the right fuse, using a multimeter. Also, with the fuse out, one should have infinite resistance to earth, and the other should have about 4 ohms I think, assuming about 20W per reversing light bulb (if that's reasonable).

Also with the fuse out, what is resistance between these two wires - it should be infinite - if it's not then is it possble they've been squished together somewhere? Otherwise maybe the ignition feed itself in the engine bay is feeding the reverse light or some other loom problem - like you say....

Hope you get it sorted

Ewen

[ewenmaclean]

Hi Karl,

the main test I would suggest for now:

1) Check the resistance between the two wires at the switch with the fuse out - put the red multimeter probe on one wire, and the black one on the other (assuming you have colours).

There should be no way these wires can be connected once disconnected from the switch - one goes to the fusebox and one goes through the reverse lights to earth. If you switch your multimeter to ohms, go for the greatest possible resistance setting which should be something like 10k Ohms, then see the reading:

--- infinite resistance (on digital this will be a 1) - they are not connected. Your reverse lights must be getting power from somewhere else.

--- a reading other than infinite (not showing 1) - probably they have been squished together before the switch... (other alternative is that the feed from the fuse box is earthed but I don't think it's this as you aren't blowing a fuse).

Let us know how you get on, and if that throws no light on it then you can try testing the voltage between various wires and earth to see where the reverse light feed is getting power from.

Good luck

Ewen