Wiring into / out of Tach.

[AshM]

Hoping for some electrical expertise please.

The topic is the wiring in/out of my Tach.

The female plug on my new (Autosparks) loom has three wires;

- Green
- White
- White with red trace (a small strap of red around the wire).

The male plug on the end of the wiring coming out of the Tach. has the same three wires. All good except when I mate the two halves of the plug the white/red trace wires are crossed.

Do I need to swap the white wires in one half of the plug to ensure white aligns with white and red trace with red trace?

Appreciate any opinions.

Thanks
Ash

[cactusman]

Probably not....the white and white with red trace are the current pulse feed to the tacho...they essentially connect together. The white will be switched live and the white with red trace will go to the coil. The tachometer won't care which way I suspect but it is slightly odd that autosparks have got them the wrong way around. The green btw is the fused switched supply for the tacho electronics. This must be correct. Also important that the tacho case is grounded....think there will be a black wire with a metal tag that fits over one of the threaded fixing posts? Incidentally the wiring diagram I have shows two white wires...either way round will work....

[AshM]

Thanks Julian. Comprehensive and very helpful as always.

Yes, all my wiring diagram references only showed white but I thought I had better check.

Green to green definitely aligned so no problem there.

Thanks again.

Cheers
Ash

[abowie]

I'll preface this by saying that none of my S1 cars have induction tachos so I know little about them.

I'm not sure at all about what you have in your new loom, but WR (white wire with red stripe) is the wire for the starter solenoid. It feeds power from the ignition switch to the solenoid when you want to start the car.

I'm not sure why that goes to the induction tacho at all. I would give Autosparks a ring and ask them. And then post their reply here so I can learn something.

[288gto]

Hi Ash,
I vaguely remember having the same conundrum with my new Autosparks loom and swapped the two terminals round.
As regards a red and white wire mentioned above, it’s not, it’s a white wire with a small 2 mm band of heat shrink sleeve to, I assume , denote live in.
The car and tachometer work fine with it swapped round to how in my head makes sense. Ultimately as mentioned a call to Autosparks should resolve it. I’d be interested to know what they say.

Simon

[AshM]

Thanks for all of the replies.

The conversations with Autosparks have been a little strange as they are insisting my male plug is not standard. It is 100% original. Prior to this winter’s work the wiring of the car has never been touched.

They are obsessed with the plug issue whereas actually the query is simply a wiring question. Do red dash wires have to be joined?

So I am going to leave as-is and see what happens when the car is re-started. If the Tach does not work then I will swap the wires over. Although it will be a few months before I am in a position to check. Engine still with re-builder.

Just to finish - besides the strange conversation re the plug I have been absolutely delighted with all of the Autosparks looms and customer service.

Cheers
Ash

[288gto]

Interesting Ash,

It was a while ago but definitely remember some head scratching and altering something. I'm pretty sure it was the terminals though I may have pulled those off and swapped the red heat shrink to denote live in and then re soldered them on. Sorry to be so vague. As you say other than that little anomaly I was really pleased with the quality of the Autosparks looms and would happily recommend them.

Simon