Rear Tail Lights not working

keninnsw · Member

Rear Tail Lights not working

Possum3 · Guru

Aust Standards say Green coloured wire is for earth when using AC (249V.

Earth is usually Black for DC (12V).

As very few manufacturers follow Wiring Standards - The 12V cable is cheapest with disregard to Standards with regards to Gauge and Colouring.

Back to your question you most probably do have a faulty Earth connection - Try a substitute piece of cable attached to bumper bar or such to see if you can get current flow.

erad · Guru

You don't say what vehicle you have - that would help with diagnosis.

Do you have a towbar? Often the towbar connection takes it feed from the R side taillight. Maybe the wiring takeoff is crook.

Does the blinker light work on the R side of the vehicle? If it does, it effectively rules out a bad earth.

Depending on the vehicle, it is possible that each taillight is fused, and you may have a blown fuse.

DOEs the brake light work on the R side of the vehicle? If it does, again the earth is OK.

Bobdown · Guru

Check the 7 pin (or 12) trailer connector, a good clean out and a small screwdriver to open up the pins slightly.

Check for voltage at tug and at the tail light at rear of van.

Cheers Bob

Whenarewethere · Guru

erad wrote:
You don't say what vehicle you have - that would help with diagnosis.

If your car is a CAN bus system, a wrong LED globe somewhere can create problems.

kgarnett · Senior Member

"Earth is usually Black for DC (12V)."

Except where it is usually white;

https://www.narva.com.au/resources/trailer-plug-wiring-diagram.

Pin No.	Circuit	Wire Colour
1	Left-Hand Turn	Yellow
2	Reversing Signal	Black
3	Earth Return	White
4	Right-Hand Turn	Green
5	Service Brakes	Blue
6	Stop Lamps	Red
7	Rear Lamps, Clearance and Side Marker Lamps	Brown

Warren-Pat_01 · Guru

Hi keninnsw,
Welcome to the forum - I trust you will enjoy your time here.
There's some good advice above - as the other wires had rust on them, you can bet that the earth too is rusty somewhere. Can you run a long earth wire from your van-car plug to your light cluster? I had an issue with my Trailblazer fridge once & I was using the car's body for the 12v -ve (earth) - running a separate wire to the fridge from the battery fixed it.

Also beware - a lot of caravans use the standard 12v colour code ie black is 12v +ve , white is is 12v -ve. Possum is partially correct - if the wires are red & black.

Happy hunting (you may need an assistant)!

keninnsw · Member

Thanks to all those who answered.

I have tested the socket on the vehicle and all was ok
I have opened the caravan plug and everyhting is clean tight and waterproof.
I have a green wire connected to the RH flasher and it works.
When it stops raining I will test the brown and red wires to make sure there's current there

oldbloke · Guru

"I had an issue with my Trailblazer fridge once & I was using the car's body for the 12v -ve (earth) - running a separate wire to the fridge from the battery fixed it."

That's a very common issue. You just cant rely on the body to work well as an earth.

Suggest you look under the van for a "common" earth. If you find one clean and tighten. Caused me all sorts of issues with my electric brakes.

Good luck, stuff like this can take forever to find.

-- Edited by oldbloke on Saturday 5th of February 2022 05:51:32 PM

Aus-Kiwi · Guru

Check polarity if one side is not working . If they are LED globes ? Other than that . Its usually high resistant connection . Not that theres much load with LEDS .

Dick0 · Guru

kgarnett wrote:
"Earth is usually Black for DC (12V)."
Except where it is usually white;
https://www.narva.com.au/resources/trailer-plug-wiring-diagram.
Pin No. Circuit Wire Colour
1 Left-Hand Turn Yellow
2 Reversing Signal Black
3 Earth Return White
4 Right-Hand Turn Green
5 Service Brakes Blue
6 Stop Lamps Red
7 Rear Lamps, Clearance and Side Marker Lamps Brown

Caravan internal wiring internationally normally is Black Positive and White Earth.

Aust trailer plugs/sockets use White as Earth.

My previous Jayco Poptop was wired Black(+) White(-). Normal US standard.

See the source image

Dick0 · Guru

If the whole cluster is not working check continuity of the Negative from cluster to plug. Had the same problem. Rusted negative return.