Where should the negative wire from the battery be earthed to?
While looking around the engine bay this morning I noticed my negative lead from the battery is earthed to the motor, but I always thought it had to be attached to some part of the frame. Is this correct?






We get a whining noise throigh our audio system that increases with rpms. Could this be part of the culprit?

 

If you look at the cable from the battery you can see it's connected to a stud on the body.

but it does look like you have some corrosion on the cable.

 

Being a DJ/audiophile, I'm going to complete the Big 3/4 cable mod on my Disco when I get some free time.

Check to see if you're getting noise on all sources... CD, auxiliary/USB, AM, and FM. That hum from you are getting could be a from various issues...

• bad/loose ground
• loose wire connections
• ground near a power source
• alternator going bad
• Insufficient gauge of stereo wires if it's a new system
• radio antennae lead

 

Yes, I get the hum noise on all sources. Mostly through the front A post tweeters. The hum gets worse as the engine warms and at higher rpms. So bad that I often prefer not to listen to anything because it's so loud. I have an aftermarket Kenwood head unit, but I think everything else is stock. I am thinking it is either a loose ground or the power lead is crossing something and picking up interference.

Honestly it could be my alternator too though. I've never had a problem with the alt, but it looks a little rough.

 

When I redid my engine harness, I pulled the big cables out of the main harness (alternator, starter, fuse box) for ease of maintenance. Unless you have corrosion, they are already quite beefy cables and don't need upgrading IMO. They also all use unique connectors/eyelets that would be a pain to replace.

For the earth, the body ground spot is too weak. It's 6mm I think. I junked that cable, and made 2 separate earth cables out of welding cable with regular eyelets (battery to frame, frame to engine). Then I installed a few new ground spots using a SS 5/16" serrated flange hex bolt, a thumb washer, and a nut.

The earth location on the alternator bracket is a pain in the butt to get to. I simply moved it to the upper hole next to the oil filler.

 

Didn't know where else to post this but found a great picture of the ground/earth points for as Disco 2...