Grounds behind spare wheel

[NSX_NA1]

How many grounds cables are there behind the spare wheel and where to they bolt to?

There is the main ground from the battery, not sure if these are on other cars but i then have additional 2 other grounds, one looks like a factory terminated cable, the other is crimped but looks like it comes from behind the ABS unit, towards the front bulkhead. I believe they both might be factory cables.

Any idea where i should ground them? share with main ground?

Where do they go / what are they for?

Thanks

 

[docjohn]

[MENTION=18194]Honcho[/MENTION]


can help..

 

[Honcho]

I have been summoned.

The front bay has five main ground points. One is for the battery and four are termination points for several sections of the front wire harnesses. If your NSX has been converted from the original ABS to the 2000+ version, you will have a ground wire coming off the big orange plug behind the ABS modulator that must be attached for the system to function. I bolt it to the aluminum ABS bracket for this purpose.

The only factory crimped ground wire loop I am aware of in the front bay is for the battery / main ground. The other four points use a joint loop that combines several smaller wires into a single loop. It is possible this wire you found is/was for an aftermarket stereo system.

 

[Old Guy]

The factory service manual is your friend. In the 1991 manual there are two sections covering grounds.

Starting on page 23-15 there is a section called Connector & Wire Harness Routing. It lists every connector on the car and has diagrams showing the location of every connector including what the attached harness looks like. The section covers all connectors including ground terminals so you need to go through the list and location pictures to find the ground terminals which are marked G. There are two or three views of the front hood because there is so much stuff in there - you will need to go through each of those views to pick out the ground connectors.

Starting on page 23-57 there is a section called Ground Distribution. That tells you what each ground terminal is connected to. Probably of less use if all you are doing is re assembling rather than troubleshooting.

Later service manuals may have changed the page numbering; but, only slightly. The sections will be easy to find. Free .pdf versions of the service manual are available for download if you use the Prime search function. If you don't have a service manual, you should follow Honcho's lead and take pictures of stuff before disassembly (although I expect Honcho also has a service manual).

Aluminum alloys form oxide coatings very quickly which are bad for electrical connections. I suggest you apply small dabs of Gardner Bender Ox-gard (about $4 at Home Depot) to the bolts, ground lugs, washers and the body contact surfaces to help ensure good ground connections. Ox-gard is a zinc bearing grease which enhances electrical conductivity when clamped under pressure.

 

[Honcho]

The factory service manual is your friend. In the 1991 manual there are two sections covering grounds.

Starting on page 23-15 there is a section called Connector & Wire Harness Routing. It lists every connector on the car and has diagrams showing the location of every connector including what the attached harness looks like. The section covers all connectors including ground terminals so you need to go through the list and location pictures to find the ground terminals which are marked G. There are two or three views of the front hood because there is so much stuff in there - you will need to go through each of those views to pick out the ground connectors.

Starting on page 23-57 there is a section called Ground Distribution. That tells you what each ground terminal is connected to. Probably of less use if all you are doing is re assembling rather than troubleshooting.

Later service manuals may have changed the page numbering; but, only slightly. The sections will be easy to find. Free .pdf versions of the service manual are available for download if you use the Prime search function. If you don't have a service manual, you should follow Honcho's lead and take pictures of stuff before disassembly (although I expect Honcho also has a service manual).

Aluminum alloys form oxide coatings very quickly which are bad for electrical connections. I suggest you apply small dabs of Gardner Bender Ox-gard (about $4 at Home Depot) to the bolts, ground lugs, washers and the body contact surfaces to help ensure good ground connections. Ox-gard is a zinc bearing grease which enhances electrical conductivity when clamped under pressure.

Great point on the Ox-Gard. I hadn't considered that and will use it on my car too. I always coat the grounds in a light coat of DC4 di-electric grease to prevent moisture contamination, but I suppose it doesn't protect against aluminum oxidation.

****EDIT****

For the OP, the factory-looking wire could possibly be the EPS ground wire, which is a large, black crimped loop that connects to the main battery ground point. Of course, your NSX would have to have power steering to have this wire. That's really the only other wire I can think of. If you don't have EPS, my best guess without seeing it is that it's a leftover stereo ground wire. Some of the higher-end installs have nicely crimped ground wires that bolt to the battery negative clamp.

 

[NSX_NA1]

Amazing thanks...

I did consult the manual and one of them i believe to be EPS the other must be aftermarket as suggested, not sure what though as it's difficult to trace.