Rear Door + Electrical Gremlins

Here's an interesting one.

I've been plagued by a a flickering of the rear heated windscreen dash light, and fog light dash light - in particular when brakes applied. My initial thinking was that the loom by the rear crossmember was chaffed, but can't see any evidence of this. Have also isolated out the towing electrics too. No change.

What definitely gets rid of it, is when you disconnect the fog light. So, I'm thinking that something is going down the live path for the fog (and this is broken when you disconnect), but not quite enough voltage to trigger the light itself. Perhaps a brake light backfeed? Have tried with a different fog light too. Same problem.

Next think I notice is that the problem is worse when the rear safari door is closed. So, i disconnect the high mounted brake light and the heated window - basically everything on the door. Now, when I turn the ignition to 1 - all the lights are on, on the dashboard. That doesn't feel right to me!

I'll think on it overnight, but if anybody has any thoughts, I'd love to hear from you!

Doug
2001 Defender 90 S/W

Earths behind the dash or at the lights.

It’s always earth first .

J

Last year I was driving my Ninety when the rear wiper started going on its own and brought my attention that the rear was filling with smoke. Cut out switch was activated.
The melt down shorting was in the flexi tube that carry rear door wires to the body. Wiper has permanent live for the park function.

tottot said:

Last year I was driving my Ninety when the rear wiper started going on its own and brought my attention that the rear was filling with smoke. Cut out switch was activated.
The melt down shorting was in the flexi tube that carry rear door wires to the body. Wiper has permanent live for the park function.

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Thats slightly terrifying!

I first thought of checking the earth/chassis/body points - one under the bonnet is solid, and has been sanded and covered in copper grease - as has the one on the rear door. Is there supposed to be one under the rear drivers side wheel arch? Can't for the life of me find it. Does it come off the loom there?

I'm wondering if this wasn't bolted back on when the rear crossmember was done? What am I looking for, just a black cable with an eyelet?

All the earths from the rear end on my tdci go to an earth point on the right (drivers) side of the transfer box. Possibly the same on your td5?

Wimblowdriver said:

All the earths from the rear end on my tdci go to an earth point on the right (drivers) side of the transfer box. Possibly the same on your td5?

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Good to know - thanks! let me have a crawl around under the landy tomorrow and see if I can find it.

So I had a crawl around under the Landy this morning. Main earthing strap on the left (passenger) side from the battery seemed to be secure to both chassis and LH transfer box mounting.

I identified where the rear loom earths on the RHS of transfer box -- two eyelets from the loom. Looked secure, but took off, sanded contacts and mount point, and applied a bit of copper paste to the faces of the eyelets and reassambled. Guess what - no more problems! Flickering dash lights now gone, and the strange behaviour when unplugging the rear door electrics have vanished.

What have I learned? Always check your earths first!

Thanks for your help everybody!
Doug