Mk3 Battery Connections (2013)

Hi, my Mk3 came to me part dismantled, I've never seen a battery in it yet and consequently I want to get the connections right first time...and some things are only obvious once you know it.

The wiring harness is mostly very nice and unmolested, but I have a Brown wire with Green tracer from the harness that goes to the fuse holder as per the wiring diagram, but the other end of the fuse holder has a RED lead with a 1/4" ring terminal which on first appearances alone looks like would go to the positive (+) battery terminal.

I think that wire has been changed and should be a Brown/Green with a ring terminal connection to the NEG (-) battery terminal? If so I can change that.

There are two RED leads from the wiring harness to a common ring terminal 1/4" I think but with a larger diameter outer......can anyone confirm where this should go please? I'm thinking POS (+) battery terminal.....or grounded elsewhere?

I also have a second single RED lead from a branch of the wiring harness that feeds the starter solenoid. (alongside the White/Red tracer and White/Purple Tracer) This RED lead also has a 1/4" ring terminal with a larger outer diameter, but this lead looks too short to ever reach the positive battery terminal so I'm guessing it may be earthed direct to the chassis near the starter solenoid?

The only wire I think has been altered is the one from the fuse holder, the two other red cables with ring terminals appear to be original.

Can anyone point me in the right direction please?.....or perhaps a photo of a correctly connected Mk3 battery would be great.

Thanks..........Mick

kettle738 said:

The wiring harness is mostly very nice and unmolested, but I have a Brown wire with Green tracer from the harness that goes to the fuse holder as per the wiring diagram,

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It should be Brown/Blue wire [NU] (as shown on the wiring diagram) not Brown/Green? Brown/Green [NG] is a lighting circuit colour.

kettle738 said:

but the other end of the fuse holder has a RED lead with a 1/4" ring terminal which on first appearances alone looks like would go to the positive (+) battery terminal.

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Sounds as as if somebody has changed or modified the fuse holder if it has a Red wire, as it would normally connect to the battery negative terminal along with the heavy gauge neg. starter wire.

kettle738 said:

There are two RED leads from the wiring harness to a common ring terminal 1/4" I think but with a larger diameter outer......can anyone confirm where this should go please? I'm thinking POS (+) battery terminal.....or grounded elsewhere?

Click to expand...

Do not connect any Red harness wire directly to the battery positive terminal if you intend to use the electric starter, only connect the heavy gauge starter positive (return) to battery positive, but ensure there is a good earth return connection between the harness and the engine so the harness return to the battery is made through the heavy starter positive cable.

kettle738 said:

I also have a second single RED lead from a branch of the wiring harness that feeds the starter solenoid. (alongside the White/Red tracer and White/Purple Tracer) This RED lead also has a 1/4" ring terminal with a larger outer diameter, but this lead looks too short to ever reach the positive battery terminal so I'm guessing it may be earthed direct to the chassis near the starter solenoid?

Click to expand...

Yes, connect the Red ring terminal either to a solenoid bracket mounting bolt, or close-by it on the frame plate. It is fixed to the lower fastener bracket of the rear side panel retaining pin of my Mk.3.
Only connect the White/Purple wire to the solenoid if your Mk.3 still has points ignition. If any type of electronic ignition is fitted then the White/Purple wire should not be connected to the solenoid.

Thank you for that, it will be a Brown/Blue wire to the fuse....Brown/Green was just me not looking at it closely enough in slightly reduced light.

I'm convinced the red wire from the fuse holder is not original and should be Brown/Blue, so that will be changed.

I appreciate the advice regarding the red leads with ring terminals, it did cross my mind that they were made large diameter for a reason and I guess that reason now you mention it is probably to make it difficult to attach them to a battery terminal........so you can't do it by accident.

I will look for suitable earthing points on the chassis for the pair of them.

Yes my Mk3 still has points.......Once it is up and running and I know it a bit better I guess electronic ignition will be on the to do list.

Many thanks...............Mick.

kettle738 said:

I appreciate the advice regarding the red leads with ring terminals, it did cross my mind that they were made large diameter for a reason and I guess that reason now you mention it is probably to make it difficult to attach them to a battery terminal........so you can't do it by accident.

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There's a photo in the Clymer manual which shows a double earth wire with what appears to be a ring terminal on the rear stud between the head steady and R/H steady side plate, however my Mk.3's wiring harness doesn't have that wire (or it has been cut off?) but it does have a harness Red with a ring terminal connected to a coil mounting plate bolt above fuel tank mounting bracket and another wire running from that point to the top of the cylinder head (steady to head bolt).

Unfortunately I don't have a Clymer, but I will take your description and work it out.

You have given me enough information to get it right and avoid an unfortunate error, so thank you again for that.

Mick.....

I seem to be in the habit of reviving old posts these days.

I swapped out my battery in my Mk3 with a newer one this weekend. But I don't trust my short-term memory for connecting the cables.

My configuration is as follows:
- no starter connected
- no big blue capacitor connected
- a modern rectifier replaced the zener diodes

Does this look right? I have the heavy gauge red cable, the red wire from the rectifier and a red wire from the harness all connected to the positive terminal.
I have the fused brown/blue wire lone connection to the negative terminal.



Thanks in advance for any advice!

contours said:

Does this look right? I have the heavy gauge red cable, the red wire from the rectifier and a red wire from the harness all connected to the positive terminal.
I have the fused brown/blue wire lone connection to the negative terminal.

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Assuming it's still positive earth/ground then - yes.

If you'd got it wrong then the fuse should have blown immediately.

L.A.B. said:

Assuming it's still positive earth/ground then - yes.

If you'd got it wrong then the fuse should have blown immediately.

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It is still positive earth. I figured it was right since the neutral light came on, but my memory ain't quite what it used to be.

Thanks!