Thread: What are these?

Originally Posted by p38arover

What colours are the wires? Often, the colours will tell you what the circuits are for.

I can see white/purple (WP) and what may be brown/yellow (NY). Brown is usually power in the Lucas codes used by LR.

WP is power to the fuel pump on a Defender but that probably doesn't apply on a 4BD1.

NY is feed from the alternator to the charge light on a Defender. It goes via a diode. I wonder if there's any chance the device is a diode? I wouldn't think so as it would need to be impossible to install it the wrong way around.

I'm just about ready to call the wreckers to take this thing and crush it.
The wiring chart I have is virtually unreadable, and does not (as far as I can tell) follow what exists in the car.

The really frustrating thing is that I can disconnect the thing that is overheating, and as far as I can tell, everything still works. Knowing my luck it will be something that won't make itself know until it's way too late.

I think that they might actually be resistors.
if you look [ame="http://www.remlr.com/documents/Wiring/VEH%20G103%20ISS%202_2_of_3.pdf"]here [/ame]
slap in the middle of the chart is a thing that says Resistor (not fitted). I think mine has them fitted ????
That is the white/purple wire.

What is throwing me is that in mine there are two of these resistor/fuse holder things (the chart shows 1) and the wiring has been split up and loops together again in a way that makes no sense to me.

I'll draw a I diagram and if my scanner still works I'll post it up.

my scanner is dead. unsurprising, it's about 15 years old.
Check out my MS paint skillz!


To add. the molded plug on the right is one of these, except is has 8 pins on each side.
disconnect that plug, and the battery, oil and park brake lights do not work.
what's odd is actually two white/black wires come out. One goes off to the ignition switch
the other loops around and goes into the plug directly underneath where the white/purple
line goes in.
on the other side of the plug it goes off to another molded plug that is not connected to anything.

<edit> Note that according to the wiring chart, the yellow/brown wire from the DIODE heads up to the
engine connector and then to the ignition relay. whereas in mine, it goes to the battery ignition light.
[ame="http://www.remlr.com/documents/Wiring/VEH%20G103%20ISS%202_3_of_3.pdf"]http://www.remlr.com/documents/Wiring/VEH%20G103%20ISS%202_3_of_3.pdf[/ame]
if you zoom right in, it says Ignition W/LT relay. Does anyone know what the W/LT stands for?

Some progress (maybe).
1. Whatever voltage is going down that 'hot' line, it's more than 10 amp - put a 10 amp fuse in there and it blew.

Interestingly, put a 10 amp fuse in the 'cold' one and it was fine.

2. As per my wiring diagram above. The 'hot' line runs up to the ignition switch. There are 2 lines in a single socket where it plugs into the back of the ignition switch.
If I unplug them, the 'hot' one cools down. There is also a 'clunk' sound from the fuse box as a relay dis engages.

I still don't quite understand, as this indicates that the ignition switch is both pulling power (to heat up the fuse) and sending power (to trip the relay) via the same post - which of course is impossible.

Off to Office works to print off an A2 size of the wiring chart to see if that makes it easier to follow.

i may save this truck from the crushers yet.


<edit> A1 size is the way to go. 59*84cm makes it much easier to follow. $2.30 per sheet is a bargain.
I've ruled out the brake check relay and ignition relay and the ignition indicator light. (disconnected and it still gets hot)

I think it's something that is attached to the ignition light relay (one of the 2 located on the top left of the firewall behind the brake booster)
unplug that and it stays cool. now have to pull the air filter out and see what's going on behind that.

I'll give you a tenner for the heap of junk!

Ill give u 20😆😆😆😆

Cheers Rod

Sent from my GT-I9507 using AULRO mobile app

Keep bidding! increase that bid by 1000 times and I'll almost break even on this thing.

I've made some discoveries.
1. Half the wiring under the dash & in the harness does not actually do anything.

2. That 'fuse' only heats up when the ignition is in the 'on' position.
Start it, and it cools off again.

3. It is definitely something in (or attached to) the ignition w/lt relay.
If I unplug that, the fuse doesn't heat up.

4. re-confirming that as far as I can tell. Unplugging it does not actually stop anything working. I'm stumped.

Currently drawing up an updated wiring diagram with my discoveries about which wires are actually used and where they go.
Hopefully someone will have a bright idea.

Might be for the glow plugs.

Cheers Rod

Sent from my GT-I9507 using AULRO mobile app

wiring 2.jpg