Rear tail light fault

Hi There,

I wonder if anyone can help me with a fault that I have with the nearside rear tail light on a 1992 Defender 90 200 Tdi. I'm using a Haynes Manual wiring diagram to assist me and a meter to check connectivity and voltage outputs.

The light itself doesn't illuminate. I've traced the wires (red/black) from the light holder to a three way connector that has a live supply, a red/black to the tail light and a red/black to the number plate light.
I have traced the live supply from to the offside rear where there is another three way connector that itself has a live supply and two consumer wires, one to the nearside and another that I've not bothered to trace. The live supply to this three way connector is coloured red/black but only shows 8v. Clearly this is the problem.

The nearside tail light and numberplate light work Ok if I connect a 12v dc supply in place of the faulty live supply on the offside rear threeway connector. So this eliminates the wiring from offside to nearside.

I've checked the fuse box and there is a good 12v supply there to the fuse and the fuse is fine. The wires that are connected to the fuse (bottom leftmost in the fuse box) are all red.

The red/black 12v supply to the offside rear three way connector emerges from the loom, that itself emerges from the chassis. I cannot see a red/black coming out of the loom at the front of the vehicle.

So where does the red/black wire connect to the red? The Haynes manual has been fantastic but doesn't show all connectors only fuse box and then lights.

Can anyone help me with this connundrum?

I'd really appreciate it.

Cheers
Andy

No matter what else you do later, FIRST find the EARTHING points for each of the back light units, undo the screws, clean it all nicely, Vaseline it and fasten it all back down again, nice and snug. Check all bullet connectors too, spray with WD40, take out all the bullets and shove them back properly. This will make good clean connections.

Only then is it worth doing ANY work on the rear lights no matter what voltages you may measure in cables.

Trick ... get a nice long length of wire that can reach from the battery to the rear lights units. Put a crocodile clip on one end. Make the other end safe and then clip the crock onto battery + positive.

Now you can test each rear light bulb filament one by one by undoing its bullet from the connector, and applying your live wire to it. It either works or it doesn't.

You'll soon work out the rest.

CharlesY

Thanks for the reply CharlesY.

I checked the bulb by swapping the 12v supply, Red/Orange, from the offside light to the nearside wiring and it all worked correctly.

I've also checked for earth leaks too and all seems well.

I'll clean and check the earths and bullet connectors in the morning. I'll get a crock clip from tomorrow too. Trip to Superdrug and Maplin then

Once that is sorted I will try to trace the wiring from the fuse box back.

It seems that there must be a connector that I've not yet found. I suspect that the culprit will be covered in cak.

The loom is open to the elements right behind the rear wheels and the protective insulation tape has lost adhesion allowing dirt etc in, so I'll get a catering pack of insulating tape and replace that too. No surprise on a 16 year old vehicle really.

Might aswell prevent future problems while I'm at it.

Had the similar problem, l/h indicator caused the stop tail to flash when the brake was pressed. Pulled out all the wires cleaned them. All was well, decided it was an earth problem so I took it out cleaned the connector and bolted it down with a new stainless bolt
Now the stop tail left and right or out as well as the number plate several hours latter I have given up cannot get them all working again
An ideas what I may have done when I cleaned up the earth lead to the body