Years ago one of my license plate lights went out. It wasn't the bulb so I got a mate who was an electrician to quickly sort it for me before I went away in the van.
They've stopped working again now and I've decided to sort out the mess that's back here too.
The license plate lights themselves do work (if you connect them directly to a power source), all the other lights on the van work fine too. I just can't get them to work when hooked up.
Anyone got any tips on an earth or something that could be missing? The towing bracket is off at the moment, that's not an earth for anything is it?
Cheers.
E D I T:
I read that the number 20 10amp fuse can go and cause the lights to stop working. I checked and replaced it this morning. No change.
I had a good think about this...
Firstly, your signature mentions a 1984 van, so this made me think of the early torpedo style fuse box.
That would have been a grey-red wire from fuse 2 to the rear of the van.
It is only at the rear of the van, that the grey-red splits off into two... grey-red for right tail light, and grey-green for number plate lights.
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But then you mention fuse 20.
Fuse 20 is the correct fuse number on the later CE1 blade-fuse type fuse box.
Grey-green leaves the fusebox from the Black multiplug at the rear of the fuse panel. Connector 'E'.
This wire comes from the first pin - therefore Pin E1.
From the later fuse box, the grey-green wire runs the entire length of the van in the big fat loom that runs along the inner face of the left chassis rail.
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You may have a couple of white barrel shaped connectors in the junction box in the front left corner of the engine bay. Each have seven pins are named T7 and T7a
One for the lights, and one for the engine to dash gauge electrics ( temperature sensor, and oil pressure sensor).
One of these barrel connectors will have a grey-green wire and a brown wire.
(Early van may have grey-red that also feeds the right tail light).
Grey-green is the 12 volt feed for the number plate lights.
On many of the original VW later wiring loom diagrams, the grey-green does not go through the barrel connector - instead to a two-pin spade connector.
The Brown wire is the ground wire.
There are a couple of branches on the brown wire, of which one should connect to a point on the left side of the engine bay with a lot of other brown wires.
You mention that the lights work when connected directly to 12 volts.
Did you connect the wires across a battery, or just supply 12 volts.?
If you just supplied 12 volts, then the brown ground wire must be okay.
Any doubt about the ground, - connect a separate temporary wire from the brown wire on the lights to a clean bit of metal on the body work.
This leaves testing of the 12 volt feed.
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There could be a whole host of reasons for the circuit to stop working.
Old wires get oxised, tarnished and generally past-it.
This can make it hard for the voltage to pass.
Same with dirty, loose or corroded connections.
First things first...
Check the brown wires on the left side of the engine bay.
Give them a good clean and ensure they are fitted securely.
Check all your connections in the junction box.
Make sure that they are clean, dry and securely connected to each other.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished
How to fix if you cannot get the grey-green to provide 12 volts to the number plate lights.
Early van - put a fresh wire between the grey-red wire in connector T7- pin 6 and the grey-green of the number plate light loom.
As the "other" lights all worked, the grey-red for the right tail light should be okay.
That is how it was done anyway from the factory.
If you are o.c.d. about what voltage or current is being dragged through the tail light wire, then you could fit a relay.
Suggested wire size is 1mm csa although original factory spec was less than this. (0.5mm in one VW manual).
The usual pins are:-
Pin 30 (12 volt supply feed).
As you have a diesel, then the battery is close to the engine bay.
Run a red wire from the battery "+" to a 10 amp fuse,
Then from the fuse to relay terminal 30.
Don't forget the fuse !
Pin 85 (relay ground).
Connect a brown wire from a clean piece of metal on the body, and link this to terminal 85.
Pin 86 (control voltage).
Connect a grey-red wire from your right tail light cluster, or the grey-red in the junction box.
Connect the other end to relay terminal 86
Pin 87 (Output to load)
Connect the grey-green wire from your number plate lights to terminal 87.
Job done.
As with any wiring, ensure that the wires are routed and secured to keep them well away from moving, hot or wet components.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished
Thank you for all this information Robsey. It is much appreciated. I had an hour spare today and tidied up some connections and tried a couple of things (no joy).
Wiring is new territory for me, so it could take me a while. I'll keep trying things on your list
