[30ONA]

Is this just an earth wire? Why is it melting the connector. This is on a j20.

[Gwagensteve]

My guess is you don't have a heavy earth from the block to the battery (or a good earth from battery to body) so everything is going through that cable.

[30ONA]

Gwagensteve wrote:

My guess is you don't have a heavy earth from the block to the battery (or a good earth from battery to body) so everything is going through that cable.

Stick battery earth. Runs inside that thick loom in the photo and disappears down the back of the engine.

[Gwagensteve]

Well, either now or at some time in the past, that wire was serving as the earth either for the motor (possibly including the starter) or the body.

I've seen this too many times.

It's not factory earth either, so I suspect it was fitted in an attempt to overcome some other problem.

Steve.

[30ONA]

So normally there is no wire there at all?

[Gwagensteve]

Well I don't know if there is normally an earth from the CAS to the firewall - it's pretty common though, but that wire isn't factory. You won't find a blue crimp ring connector anywhere on a factory loom, and it certainly wouldn't be connected to the wiper access cover.

Steve.

[30ONA]

It was melted through when I bought the car. I thought just a bad connector and replaced the whole cable. So you are right about it not being the original cable. I have found another photo on the net with the same cable.

So I guess just need to work out why there is so much current going through it.

[Gwagensteve]

Is or was?

[30ONA]

Is. Melted when I bought it. I replaced it and it has melted again.

[Gwagensteve]

So my initial diagnosis was correct.

You're missing an earth either from battery to block or from battery to body.
There is no other cause.

[30ONA]

So I should just run a large wire from the neg on the battery to the block, perhaps the lifting lug bolts.

[fordem]

Why not find the factory earth and fix that - it should run from the battery negative to one of the bell housing bolts.

[30ONA]

fordem wrote:

Why not find the factory earth and fix that - it should run from the battery negative to one of the bell housing bolts.

Bell housing. Ok that makes sense with where it is going. That's assuming it's just the connection and not the cable. Thanks I'll check out the housing connection then replace the small cable again.

[Gwagensteve]

I'm not sure I understand that post.

There should, currently, be a factory cable from the negative terminal of the battery to the bellhousing. Is that cable present?

The small cable from the block to the body is there to ensure stability for sensors and gauges and is not intended to carry any significant current.

[30ONA]

Gwagensteve wrote:

I'm not sure I understand that post.

There should, currently, be a factory cable from the negative terminal of the battery to the bellhousing. Is that cable present?

The small cable from the block to the body is there to ensure stability for sensors and gauges and is not intended to carry any significant current.

Check the main cable. Once confirmed ok, I'll replace the small earth too on the sensor housing as it is damaged.

[30ONA]

The main earth was oily from a rocker cover gasket leak. I fixed the leak a few weeks back. So I decreased the main earth at the bell housing. Removed the nut and checked the main earth wire for connectivity back to the battery. Perfect. I reconnected it with some dielectric grease and tightened up. I also replace the small earth from the CAS. This time without a connector.

So nothing obvious was found.

Only thing that I thought was weird is the earth sparked when removing it and reinstalling it. I thought that only happens if you removed the positive terminal with the earth attached.

What else could cause that old connector to melt?

I did spot this too. Old earth cut of just behind the battery.

[30ONA]

Just looked at the wiring diagram, apparently that should go straight to the battery terminal. Wonder why it was disconnected. I'll reconnect it you can't have too many earths can you?

[Gwagensteve]

If you reconnect it you can remove the fat one from the block to the firewall. You're currently earthing the body through that cable.

[30ONA]

Well they are both present in the wiring diagram. Why would I want less earths?

[Gwagensteve]

The stock earth in that location is a light cable- I meant it doesn't need to be fat (or melted). At the moment it's doing lots of work. Replace it with a smaller earth and re-instate the factory earth.