Engine mounted earth cable melted

[Garethbaker]

Hi guys, I cleaned the muck off the earth point under the alternator, has the starter earth and a few others. Discovered one of the small ones was cooked.

Can anyone tell me what systems are earthed at this point?

[phillpot]

Anyones guess what all those earths are for! But nothing looks heavy enough to be the starter earth?

[Penelope Stopit]

The loom has to be stripped back and checked, there are no options, you will possibly see what that burnt cable terminates to once the loom is stripped of sleeving and tape, going by how hot that cable has got there is every chance it's burnt throughout its length

Cause of it??????

The starter has very likely been cranked when there was a main bad or missing engine earth (battery cable)

High Amps starter current will have been drawn through any thinner earth cables that are connected to the engine and also earthed at their other ends

or

Someone has connected an unfused battery positive to the other end of that now burnt cable which would burn it out

Nasty but repairable

You might get lucky and find only a short length has burnt

Viewed the following image in a coolant leak topic that you posted to, shows the main engine earth cable, don't forget to earth the main battery/chassis to engine cable at the same earth point

Edited by Penelope Stopit on Thursday 30th April 15:54

[Belle427]

I can’t remember what the negatives are for but they are important.
You should have a large gauge cable on that bolt that goes to the chassis in the front drivers wheel arch area, this is the main engine earth.
I can’t see that cable in your picture but it’s visible in the one above.

[Garethbaker]

Thanks guys, sorry I wrongly assumed it was a starter earth because of the size but I get it now, that's the return for engine stuff via the chassis. So anything earthed through the engine is basically routed through this bolt including those whose wires also terminatee here?

I've stripped back the loom as far as the bottom of the fuel rail and replaced what I can see with as long a black cable as I could find. Hoping to finish the water leak I'm doing and then go back to this and continue from where I got to.

Interesting, I found the loom was full of hyd oil presumably from a previous leak/spill from the reservoir above. Not sure if this is a concern or just yucky.

I found a burn wire under the dash demand the radio a year ago and never found out what it was for, hard to believe it terminated to earth via the engine block.

But I'd be keen to know what systems do use this point through to the chassis. The bible has nothing on it unless I an reading the circuit diagram wrong?

[Belle427]

SteveD will be your man to confirm what they are and may be along soon, I seem to recall them being for the ecu and air con system if fitted.

[Steve_D]

Functions (not individual wires) earthing at the timing cover.

• 4 earths from ECU
• tune resistor
• OBD
• fault diag. connector
• A/C

Steve

[Penelope Stopit]

Garethbaker said:

I've stripped back the loom as far as the bottom of the fuel rail and replaced what I can see with as long a black cable as I could find. Hoping to finish the water leak I'm doing and then go back to this and continue from where I got to

You will get there, it's a case of having to, leaving burnt wires in the loom is not an option

[Garethbaker]

Thanks guys, I will investigate further after I've fgot the car back together and can move it out of the corner. I've got a Haltec ECU that working fine, I'm wondering if the burnt wire is maybe part of the original, and could be redundant? I assume Haltec is an upgrade and not original?

[Belle427]

Garethbaker said:

Thanks guys, I will investigate further after I've fgot the car back together and can move it out of the corner. I've got a Haltec ECU that working fine, I'm wondering if the burnt wire is maybe part of the original, and could be redundant? I assume Haltec is an upgrade and not original?

An unusual choice but Haltech are supposed to be very good.