Rorie · Feb 28, 2019

i’ve re-wired my G reg 90 following the bulkhead change out. Previously the engine was changed out for a 300tdi.

I have a thick red cable coming off a bolt on the starter- no idea where it goes. I don’t know if it was connected to anything before I took the bulkhead out.

I found a previous thread on another forum and it looks to be an identical cable for a similar situation. The answer seemed to be that the 300tdi had a fuse box in the engine bay, so this would have fed that. As it’s an old 90 and I don’t have the engine bay fuse box, I don’t need that cable.

But! I tested the cable and it has continuity to earth. Also, when car running, there is zero volts if I check between it and earth. So how could it feed the fuse box?

Initially I thought it was an earth cable but the wrong colour, so connected it to earth and the car wouldn’t start.

Any thoughts?

Rougharse Racing · Feb 28, 2019

It looks like someone has used an old battery positive lead as an earth strap. The other end needs to be bolted to the chassis, assuming that it is the same cable in the bottom picture and bolted via the starter motor's mounting bolt.

Scooby22 · Feb 28, 2019

They may have removed the red lead from the live terminal and used it as mentioned above.

Rorie · Feb 28, 2019

I assumed it was an earth as it was onto the mounting bracket of the started, but when I hooked it onto a good earth, the car wouldn’t turn over. I turned the key and I just heard a relay clicking.

Disconnected it from the earth and it worked fine.

So I assume the cable to the engine bay fuse box would have come off the front of the starter, rather than the mounting bracket?

Does the starter need to have a chunky earth cable?

Rougharse Racing · Feb 28, 2019

The only cable that should be fitted to the mounting bolts should be an earth to the chassis.
The main battery cable should attach to one of the two large terminals on the starter solenoid, the thick brown wire from the alternator and the thick brown wires that connect to the main loom connect to the same terminal. If there was an engine bay fuse box like 300tdi's it would connect here via a thick brown wire.
If you connect that thick red cable to this terminal whilst the other end is attached to the mounting bolt you will get a sh1t load of smoke a lot of sparks and possibly set fire to your vehicle.
The engine needs a chunky earth cable, usually attached via an engine mount to block bolt or the starter motor mounting bolt.

Rorie · Mar 1, 2019

I agree with what your saying, that was my thinking when I was re-wiring. However, with it connected to earth, the car doesn’t start. Disconnected the car runs fine.

I assume while disconnected the Starter is just earthing through another route.

If I earth the loose end of the cable, the car doesn’t start- I hear a relay clicking from a relay when I put the key all the way over.

So why would this be? Doesn’t make much sense to me!

tottot · Mar 1, 2019

If you are connecting that cable to the second connection on the starter solonoid then current will not flow through the starter motor and it will not go. [starter earths it's self through the engine block] .Hold the starter on any length of time and as RR says there will be smoke and fire. What ever it did before the cable is not needed now so just use as an extra earth cable,bolt to the chassis. Extra earth's between chassis/ body/engine gearbox on an older landy can only be a good thing

Rorie · Mar 1, 2019

No, sorry, maybe I am not being clear.
One end of the cable is connected to the bolt on the starter as shown in my photos.
The other end is loose.
If I keep it loose (I.e isolated from everything), everything in the car works.

When I bolted the loose end to the chassis, the car wouldn’t start and I heard a relay clicking.

jamesmartin · Mar 1, 2019

Rorie said:
No, sorry, maybe I am not being clear.
One end of the cable is connected to the bolt on the starter as shown in my photos.
The other end is loose.
If I keep it loose (I.e isolated from everything), everything in the car works.

When I bolted the loose end to the chassis, the car wouldn’t start and I heard a relay clicking.

connecting that cable to earth as it is at the starter bolt anyhow cant effect the starter, the earth for the starter is usually bolted to the transmission,people add others as in your case

mick 1986 · Mar 1, 2019

Rorie said:
No, sorry, maybe I am not being clear.
One end of the cable is connected to the bolt on the starter as shown in my photos.
The other end is loose.
If I keep it loose (I.e isolated from everything), everything in the car works.

When I bolted the loose end to the chassis, the car wouldn’t start and I heard a relay clicking.

How is your engine, gearbox, and transfer box currently connected to your battery? Do you have the main battery earth out of the battery box, to the chassis, and then transfer/gear box bolt? If you do a resistance test from a clean bolt on the block, back to the battery, what value do you get without the starter motor “extra wire” connected to the chassis?

Rorie · Mar 1, 2019

jamesmartin said:
connecting that cable to earth as it is at the starter bolt anyhow cant effect the starter, the earth for the starter is usually bolted to the transmission,people add others as in your case

Makes sense. So I wonder what’s going on to cause the issue! I’ll look again today.

I have battery to chassis and battery to transfer (or gearbox, can’t remember!). I’ll check the resistance of that wire again and report back! I’m so confused!

jamesmartin · Mar 1, 2019

Rorie said:
Makes sense. So I wonder what’s going on to cause the issue! I’ll look again today.

I have battery to chassis and battery to transfer (or gearbox, can’t remember!). I’ll check the resistance of that wire again and report back! I’m so confused!

usually at the rear of the transmission you have a thickish earth cable connecting battery to chassis and to transmission connecting another to the body is a good idea, ie chassis to body or transmission to body, poor earths are a common failing on old landies

zeaphod · Mar 1, 2019

Disconnect the cable from the starter. If you want to add another engine earth (you should have a braided strap already) you could use the strap between the chassis and engine block.

mick 1986 · Mar 1, 2019

zeaphod said:
Disconnect the cable from the starter. If you want to add another engine earth (you should have a braided strap already) you could use the strap between the chassis and engine block.

That was going to be my advice, if the main earth cable is good and connected.

I don’t have an earth braid from engine to chassis, and nothing from chassis to body either.

Rorie · Mar 2, 2019

Right, so I had minimal resistance between the cable and earth, but also the engine and earth, so defo an earth cable.

Reconnected it to an earth and the issues I had starting never happened, so must have been something else causing that problem!

So I just disconnected the cable and chucked it.

Thanks for the help folks!

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