Main earth connections

[1972nail]

Being a pessimist most of the time I like to do a bit of preventative maintenance which may prevent that elusive gremlin that stops the car in it's tracks when you most need it to work perfectly.

To this end I wish to check and clean all the earth terminals I can find. There are of course minor ones to lights etc but where are the main connections? So far I've identified the one on the boot floor under the carpet and the main engine earth strap. Are there any more at ECU's, fuse boxes etc which should be examined?

 

[Magicarcher]

A document that will help you can be found here http://www.unofficialbmw.com/images/08 E85 Power Supply.pdf (NB the URL will probably not work, it never seams to for me, so you may need to cut and paste it into a browser).

Good luck in your quest though. BMW have been using KSK harnesses for over 20 years, KSK harnesses are made by bundling together a whole load of sub harnesses each designed for a small number of features. To make this easy to assemble in the harness manufacturing process they use ground connectors that bunch together a whole load of grounds into a single place. If you don't know what I mean, take a look at this post on another site, half way down you will see a ground connector http://www.bimmerbrothers.com/e36-oe-keyless-entry-retrofit/. They are not all easy to get to, being located behind trim panel and if you are planning on undoing them, cleaning and reconnecting them, there is a risk you may do harm than good.

 

[1972nail]

Thanks for your reply and I see what you mean about the wiring being complicated. The connectors that are in the links are a bit more specific than the ones I was thing of. I'm really looking at the main ones that that are likely to give problems or are known to give problems.

 

[Ducklakeview]

TBH, the under bonnet ones are pretty easy to locate. As for the rest, you'd need to remove pretty much all of the interior and boot trim!

Mike

 

[Magicarcher]

I'm really looking at the main ones that that are likely to give problems or are known to give problems.

All grounds are likely to be shared with multiple circuits generally there will be two types of earths "clean" and "dirty" clean earths will be used to bundle together the earths for nearby electronic modules, dirty earths will be used to bundle together higher current earths that are either dirty (solenoids, motors) or don't need to be clean (lights, HRW spring to mind). To find out what each does you will need to access TIS, each earth will have a wiring diagram and it will show the circuits it contains. If you intend to add your own circuits don't put dirty loads on clean earths else you could end up with spurious electronic behavior.