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seriesonenut

Member Since: 19 Nov 2014
Location: Essex
Posts: 1230

Please check my thinking - Earth Fault?

So after a wet and potholed drive in and out of a farm I developed some faults including , only one side light, brake lights on (not the nearside as that is now just dead) with the ignition on. Hazards working but no indicators after I found this mess stuffed on the rear cross member behind the off side rear wheel

wires by Richard Holmes, on Flickr

That was after I cut off multiple cable ties and washed off mud and road dirt with electrical cleaner

Am I right in thinking all of the feeds to the rear come through through a single loom multi cable? Everything else looks like connections to the nearside /offside individual lights. Rain and wind stopped me today.

This all feels like an earth problem, is there an earth connection at the rear or is it all fed via the loom from the front?

Thanks 1984 One-Ten CSW
2010 XS USW (sold)
1957 Series One 88 diesel
1958 Series One 88 4x2

26th Jan 2025 12:53pm

donmacn

Member Since: 06 Nov 2017
Location: Nth Scotland
Posts: 1852

I’m fairly sure all the feeds in Tdi loom (it’s the 300 I’m familiar with) come along the OS chassis rail then they’re supposed to go up through the seatbox/wheel arch and into the wiring cover behind the lights.

From your pic it looks like the loom doesn’t go back inside the car, and the connections have been made behind the crossmember?? That wouldn’t help.

If it were me I’d try and figure out which functions on the main loom are working when they should and then fault find from there.

Afraid I don’t know, or have forgotten where the earth point is. Mainly because when I rewired this part of my car, with additional circuits, I put in a dedicated earth point back to the battery.

Edit - thinking further, if some of the lights are working (hazards) that suggests the loom earth is ok, and you could test further based on that known good earth? Sorry. Probably not being much help,as I can’t answer your specific question about where the factory earth is supposed to be. Donald

1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong
(The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html )
2000 Range Rover P38 4.0L V8

in the past..
RR classic - fitted with 200Tdi
1984 RR classic - V8 with ZF auto box
1993 Discovery 300Tdi

not to mention the minis and the Type 2 VW camper...

26th Jan 2025 2:09pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20599

Likely loose ground point on chassis or transmission, in particular the rear loom.
The pothole probably loosened it, and as it appears you are having issues on multiple circuits then that’s likely a common ground.

Have a look on the sides of the transmission to the rear, there is likely a ground eye or two there for the rear loom.
There is on the Puma, the earlier models are likely similar.

Worth checking battery clamps and main ground as well.

If you do find a loose ground, I’d clean it well, reinstall with a tiny bit of low strength loctite, and then myself I spray Dinitrol black over the top externally as that keeps most water and ingress out.
You can put a little dielectric grease on the mating surfaces, but being clean is of more use and keeping water and dirt out, and stopping the fixing from loosening. GBR
⛽️🛢️⚙️🧰💪

Last edited by custom90 on 26th Jan 2025 6:23pm. Edited 1 time in total

26th Jan 2025 2:50pm

seriesonenut

Member Since: 19 Nov 2014
Location: Essex
Posts: 1230

Thanks both

Given it is multiple circuits it must be a common ground. I will have a look up front as well as the back. Given I am working on the driveway if I can resolve I can tidy the rear loom when the weather improves a bit 1984 One-Ten CSW
2010 XS USW (sold)
1957 Series One 88 diesel
1958 Series One 88 4x2

26th Jan 2025 4:05pm

MarkBrown

Member Since: 03 Oct 2022
Location: Mid Wales
Posts: 512

1983 Defender 110 Other HT Auto Keswick Green

I had similar problems on my old 110. On that the loom went through the chassis and apparently after 30 odd years the wires can run through and short/contact each other. I found I brake light wire at the bulkhead and cut it, then ran a new wire through.

On my rebuilt 110 I ran the loom through ducting inside the body capping, cut off and soldered all unnecessary connections and make all joins inside the car.

The only problem I had was with bad contacts within the brake and side light fittings ( they were new ) which sorted by fitting led lamp/brake units.

The other problem was that on mine the heater/flashers/ brake lights are all on the same fuse, so when they short you've got no brake lights, no heater blower and no flashers, which is no good. 1983 110 automatic OM606

26th Jan 2025 4:15pm

Roverdrive

Member Since: 11 Aug 2024
Location: Wirral
Posts: 18

On my 110 the loom connections are behind the panel on the offside ( UK )rear of the vehicle by the door.
There is an earth post in there for the rear lights plus other accessories i have.

HTH
Mike

26th Jan 2025 4:24pm

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