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Negative bonding
hearnia - 7/8/05 at 06:08 PM

Ok, so I'm nearly ready to power up my loom and was just carrying out some checks before I go any further.

I came to checking that the negative side of the battery was bonded to the chassis and engine etc. but found it was open circuit on my meter?!?! Am I being completely retarded or should all of these items be bonded?

The engine and chassis are bonded with low resistance so the problem is not there.

I've used the standard R1 loom and extended parts and added parts where necessary. Havent quite finished wiring in the lighting switches and ignition but I dont expect this will have any effect?

Any ideas would be greatly appreciated.

Cheers
Joe

britishtrident - 7/8/05 at 06:24 PM

What have you go the main battery earth cable bolted to ? it should run to either the chassis or the engine/gearbox.

rusty nuts - 7/8/05 at 06:31 PM

Check that the battery connections are clean and tight. Dirty terminals can cause an open curcuit., clean the battery and the lead .HTH

hearnia - 7/8/05 at 06:33 PM

The main battery earth cable goes from the negative side to a place where the positive and negative bolt and there are fuses in between them.

Then there is a second wire which bolts to the engine and then onto the chassis (linked into the loom with another connector).

I'm going to go and have another look in a minute to try and spot anything obvious, once I've cleared my head of solder fumes.

rusty nuts - 7/8/05 at 06:40 PM

Do you mean that you have a fuse in the battery neg to chassis/ body side of things?

johnjulie - 7/8/05 at 06:47 PM

The -ve earth side of the battery should connect to the chassis, and the chassis should be connected to the engine.
Cheers J&J

hearnia - 7/8/05 at 07:13 PM

Sourced the problem now, there was a slightly fatigued spade connection that needed cleaning.

Thanks for your help.

britishtrident - 10/8/05 at 12:16 PM

The main earth shouldn't connect through a spade connector it should run straight to the chassis or engine.

chrisf - 10/8/05 at 01:14 PM

quote:

...it should run straight to the chassis or engine.


Not both?

--Chris

David Jenkins - 10/8/05 at 01:28 PM

I have a welded-in stud on my chassis, just below the battery. The negative battery lead is fixed to this with a nut, as is the hefty braided engine earth strap and a few other loom local earths.

The negative lead should be the same thickness as the starter lead (or even thicker), and the engine earth strap should also be bigger than the starter lead if possible.

David

britishtrident - 10/8/05 at 03:44 PM

quote:
Originally posted by chrisf
quote:

...it should run straight to the chassis or engine.


Not both?

--Chris




Some production cars do it with a single cable with 3 connections, but normally it dosen't matter as long as you have heavy duty earth braid between the engine and the chassis.

NS Dev - 11/8/05 at 02:06 PM

.......................and we all know about what happens if you forget that item.......................oops.......................burning speedo cable and speedometer