Mystery Lead

[TPS]

Starting my M42 Touring the other day, noticed that this lead had come off (middle one):-



The car still runs ok, without it, but I haven't started it since, fearing it to be an earth lead. Anyone know what it is?

Thanks

Phil

[Brianmoooore]

How many wires are coming off the terminal, other than the battery negative lead?

[TPS]

Just the One Brian

[TPS]

On the left is the Battery Negative terminal, to the right of that is the wiring going to the Coil(s), next to that is the suspension Turrent with the broken terminal, & to its right is where the Battery Negative Terminal, comes in from the Battery.

Will, the broken wire joins the main wiring on the bulkhead, & it appears to go towards the C101

[DanThe]

If you pull back the insulation, is it a brown wire? As per my other discussion with you, I think it is the main ground cable from the engine loom. If the insulation on it is brown, this will confirm it.

It will be, I wouldn't run the car for too long without it connected as the rest of the loom will be getting rather hot

[Brianmoooore]

I wouldn't run the car for too long without it connected as the rest of the loom will be getting rather hot

This is true, but I can't think where the auxiliary earth is, which must be present if the car runs. On a M20, it would be via the oil level sensor, but this is a M42.

[TPS]

Right, I've cut the insulation, 2 wires are underneath, 1 thick brown cable, & 1 thinner brown & orange cable

[Brianmoooore]

That's as it should be, and are the main (and should be only) earths for the complete engine loom.
Could the shields of the cam and/or crank sensors be providing the axillary earths?
Whatever is, it wasn't designed to carry the current, so get the main earths reconnected before running the engine.

[TPS]

Thanks Everyone