Earthing

[dpetersen]

Question for you guys,
I have fitted a little pillar gauge as a temperature gauge as mine was buggered but, when I turn the headlights on it goes up about two degrees, high been another two degrees, a/c another two degrees.
I read somewhere that the GU had a poor earth strap. Do you think this is what is causing it?
It's a 2003 gu 3 zd wagon.

[Woof]

Bugger did not have my glasses on and though it was a welcome from an extraterrestrial..............EARTHLING..LOL

[Bigcol]

yes it is an Earthling problem (for Tuppa)

you cannot run the wire for the lights from the dimmer switch
(or Vise a versa)
cannot remember now

ET is the one to speak to - he will know, I remember he said something about it ages ago.......

[Rocket55]

The GUs do have bad body to chassis earthing, add an additional earth in, I put one here. This is essentially under the drivers seat.

http://i1083.photobucket.com/albums/j396/Rocket5555/Build%20Pics%20Patrol/722876A9-F931-44B6-A471-A16DB3405074_zpssxa67h6c.jpg (http://s1083.photobucket.com/user/Rocket5555/media/Build%20Pics%20Patrol/722876A9-F931-44B6-A471-A16DB3405074_zpssxa67h6c.jpg.html)

This is what I did for my pillar pod lights and it works perfectly. I patched into the light thats on the cig lighter for the 12v power, and for the earth I pulled the corner of the dash apart to get to the back of the dimer switch and connected the negative wire to the PINK wire, now the gauge lights only come on with the headlights AND they dim properly with the dimer switch.

[threedogs]

I know on Tojo's they had an earth strap for different parts/sections of the 4x4.
like engine bay/fire wall, dash, cabin, passenger and say cargo area. Dont see how
Patrols would be different. I even have an earth under my UHF antenna direct to
the neg of the Battery

[dpetersen]

Fixed it.
The installer fitted the earth to the battery. Removed it and fitted it to the body. All good now.

[4bye4]

May be a stupid question but wouldnt running earth back to battery be best earth possible? Im not great at electrics but have multiple earths back to negative terminals. This not best practice?

In theory you are correct. The problem is that in motor vehicles we only have a small voltage (12Volts) so in order to get sufficient power to operate various things, we need big wires to keep the losses to a minimum. Although we may use small individual wires from power +ve to say a light, everything on the vehicle has to return to earth or -ve battery. We can run a hole heap of various sized wires from the -ve terminal or we can use the largest "wire" in the vehicle, the chassis and body of the vehicle. The trick with this is to make sure that all the chassis and body bits and other bits of tin are all joined together electrically and the battery(ies) are all joined to the body. This is where Nissan sometimes comes adrift as the body to chassis to engine block are not always joined together electrically very well. Earths straps of large diameter wire with good tight connections fix this problem. Dpeterson's problem with gauge interference was probably due to the earth return wires on each gauge being too small, so the return path was using other return wires ie. the guage wireing earth itself and in doing so was making the gauge read incorrectly. The most common or obvious earth problem is on trailers when they are not earthed to the towing vehicle properly and you see brake lights flashing when indicators are on and so forth. Hope that helps.;)