240Z Earth/Ground - rear end.

[Rob Gaskin]

Hi folks, I would be intrigued to know how the loom at the rear of a 240Z is earthed. If anyone has their car dismantled and could have a look for me that would be interesting.

As with the rest of the car I've opened my loom to check circuits and remove unnecessary wires e.g. aerial power, speaker leads and marker light circuits. Again I have repaired a couple of issues - this is proving so useful and satisfying.

On my car the only earth was from the fuel gauge sender circuit! All the lighting earths are joined (factory joins) and connect (with the fuel sender) to a heavier cable that runs up to the dome light (and that wasn't connected). No earth comes from the front of the car apart from the HRW.

When I unplugged my sender connector nothing was earthed at the rear!

I will be providing good earths to the body as I did with my lighting at the front of the car.

 

[johnymd]

The main rear earth is inside the car just behind the number plate. Not sure if I can remember any others at the back. Maybe near the fuel sender/electric pump location.

 

[Rob Gaskin]

The main rear earth is inside the car just behind the number plate. Not sure if I can remember any others at the back. Maybe near the fuel sender/electric pump location.

Thanks John, mine isn't like that but it will be now. My electric fuel pump is earthed near the pump - I renewed that. So only one wire to the pump.

The fuel sender must be earthed and incredibly was earthing the whole rear end.

As I keep saying, this is proving to be such a good exercise.

I'm modifying my wiring a lot but first of all I'm fully understanding what I have.

 

[MaximG]

The main rear earth is inside the car just behind the number plate. Not sure if I can remember any others at the back. Maybe near the fuel sender/electric pump location.

That's interesting mine is earthed by the fuel tank with a Machine screw into the chassis rail. I wasn't aware it was there until I took the car apart for its full resto. Fairly confident this is stock as well. Not sure if I have a picture will have a look.

Just to add I have no other earth at the back.

Mike

 

[Rob Gaskin]

That's interesting mine is earthed by the fuel tank with a Machine screw into the chassis rail. I wasn't aware it was there until I took the car apart for its full resto. Fairly confident this is stock as well. Not sure if I have a picture will have a look.

Just to add I have no other earth at the back.

Mike

So your's is like mine Mike. These cars are quite poor as far as wiring circuits go - it's been an eye opener. However there were bodges on my car too.

 

[MaximG]

So your's is like mine Mike. These cars are quite poor as far as wiring circuits go - it's been an eye opener. However there were bodges on my car too.

Just had a look through my pictures and it doesn't quite show the location I'm after. I do however know its as the loom goes through the floor the earth point is on the chassis rail opposite. I was presently surprised that the screw came out considering.

That's one thing I did do when I had everything out Rob and that was tidy the wiring. Mainly the engine bay loom as that was in a bit of state which also included a bit of rationalisation. I also rerouted some of the Dash loom to my liking. Reinstalling the rear loom was a little tricky but was aided as the car was on its side at the time. The most difficult part at least for me was getting the dome light wiring back in.

Mike

 

[Paul_S]

This probably doesn't help much, but I took this pic whilst I was chasing wires some time ago. You can see my earthing wire goes through the floor close to the rear light cluster (RHS as you look at the rear of the car)

 

[240L31]

My 8/71 240z has two ground points at the rear:
Below trunk/above fuel tank (sheet metal screw to chassis rail)

Behind licence plate light

I can't think of any other ground connection there. I had the wiring harness removed, so I am pretty certain.

 

[Rob Gaskin]

Thanks guys. Yes Paul same as mine - yellow to sender, black earth. Nothing else for 'rear end' earth. I now have a second 'strap' to the body.

Mike, had all my 'dome' and HRW wiring out and sorted - nightmare with a roll-cage in situ.

If I didn't understand wiring I couldn't afford this to be done by a 'professional' and it's like that for a lot of people so wiring is bodged. It's not 'sexy' but sooo important.

 

[Rob Gaskin]

My 8/71 240z has two ground points at the rear:
Below trunk/above fuel tank (sheet metal screw to chassis rail)

Behind licence plate light

I can't think of any other ground connection there. I had the wiring harness removed, so I am pretty certain.

So you have two - luxury!

 

[Rushingphil]

As the posts above - I have an earth on the rear chassis rail from the sender unit. I also have an earth on the inside of the rear bumper from the rear number plate light. Unfortunately I don't have a clearer picture. My loom is disconnected but still in situ if you need any other pics.

 

[Rob Gaskin]

As the posts above - I have an earth on the rear chassis rail from the sender unit. I also have an earth on the inside of the rear bumper from the rear number plate light. Unfortunately I don't have a clearer picture. My loom is disconnected but still in situ if you need any other pics.

Thanks Phil. Is the earth to the number plate light actually connected to the metal of the bumper or is it 'grounding' the light bulb holder.

 

[Rushingphil]

Thanks Phil. Is the earth to the number plate light actually connected to the metal of the bumper or is it 'grounding' the light bulb holder.

Hi Rob,

The earth is connected to one of the bolts that holds the actual bulb holder to the bumper:

 

[Rob Gaskin]

Hi Rob,

The earth is connected to one of the bolts that holds the actual bulb holder to the bumper:

View attachment 37732

Oh ok thanks I wonder if that's original. A lot of cars (like mine) have the overhead number plate lights and plain bumpers

 

[Turn & Burn]

Rob, mines a 260 but has the upper number plate lights (as well as the lower) the earth is internal as shown in the pic. There’s also another one that’s easy to miss unless the seats are out this is on the rear seat support, I guess this would count as a rear earth too.

 

[Rushingphil]

Oh ok thanks I wonder if that's original. A lot of cars (like mine) have the overhead number plate lights and plain bumpers

To be honest, I have no idea. Seems a strange way to me. Far better to earth to the main shell than rely on numerous connections between the bumper and shell. I'll probably do it different when I put it back together again.

 

[Rob Gaskin]

Rob, mines a 260 but has the upper number plate lights (as well as the lower) the earth is internal as shown in the pic. There’s also another one that’s easy to miss unless the seats are out this is on the rear seat support, I guess this would count as a rear earth too.

Interesting, perhaps they learnt a bit between cars. Mine doesn't have those - don't worry I haven't missed anything. I have a 260 too and I do think (like many people have said) that the 260 is an improved car in many respects.