Hi all,
Does anyone have a diagram how to connect the rev counter ?
I do not have a stabiliser and the car is negative earth.
I've seen some discussions mentioning a "loop" can someone clarify this point for me ?

Thanks for your help.
Gino
Milano
Italy

This is the later type with the ignition wire loop inside.
I don't have a photo of the early type with the external loop.

Alan.

The wiring will depend on whether it is an RVI or RVC-type. It is written in very small white writing on the face.

Paddy

Hi Paddy and Alan,
Thanks for your comments. I can say for sure it isn't the later type because it is different on the rear.
Does anyone have a photo of the earlier type ?

Thanks
Gino

Does it look like this? This is the original tach from an S2. The loop has to go through in the correct direction. My usual procedure for determining the correct direction is:
1. Take my best guess, install the tach.
2. Observe that the tach doesn't work.
3. Remove tach, put the wire through in the other direction, replace tach.
4. Observe that the tach works.

MMMMM..not sure. I'll take a pic tomorrow and post it.
This is for my S3 coupé.

Gino

If it doesn't look like either of these, I think you have an RVC rev counter. Can you confirm?

Paddy

I think a S3 would have the early type, rpm shown as 10 to 80 x 100 on the face. S4 had the later type, rpm 1 to 8 x 1000.

This shows the direction of current flow through the loop. For negative earth the arrows point towards the coil.

Alan.

Hi Paddy and Alan,
Finally got the photo taken and yes I can confirm it is an RVI type 2402/04.
I have connected the lights up to the unit and work ok.
The is a female connector with two wires coming from it Red/Grey....i need help from here.
Car is negative earth now.
Thanks Gino

I think the Red/Grey wires are for the brake fail warning, if you have one. You should have a green wire connected there (fused 12 volts - ignition on).

Alan.

Gino,

The brass-coloured fitting on the left side of your photo looks like where the wire needs to loop around. See Alan's blue picture just above.

The wire that loops around here is the one at goes from the ignition switch to the +ve (or "SW") terminal of the coil.

Is the car running ATM? If so, this wire must already exist, but at some point it was removed from the rev counter. You need to see if you can find this wire and see if someone just removed it, or they maybe replaced it with a direct wire from the ignition switch to the coil.

Paddy

Hi Paddy / Alan,

Thanks for your replies.
Paddy I'm lost on this ATM, what's ATM ?
Yesterday I tried everything, blew lots of fuses, even tried calling some uk friends but no luck!!

Here's the situation I need to clear up.
I have this loop connection thingy to connect and the diagram I received is self explanatory, but where does this wire start and where does it finish ?
Also I have a male terminal coming off the rev counter what do i need to attach to this ?
I bought this tacho used and sincerely understood it was complete.
Does it matter if I have changed from positive earth to negartive ?
Thanks
For your help.
Gino

Gino

What does it say on the front of your rev counter ,it should say positive or negative earth?

John

ATM - at the moment

cheers
Rohan

Sorry Gino, I should have been a lot clearer.

ATM = "at the moment". I was asking whether or not the car is running without the tach connected.

If it is, then there is already a wire (somewhere) from the ignition switch to the +ve terminal of the coil. (On some coils this terminal is labelled "sw").

This is the wire that must be coiled around the terminal on the back of the tach. Just to be clear, the wire goes from the ignition switch to the coil and *it already exists* - you should not be running a new wire.

The tach also needs a +ve supply, which is what that other terminal is for.

There is some more info, and guidance on conversion from +ve earth to -ve earth here:

http://www.lotus-cortina.com/electric/convert.htm

I hope this helps and sorry for the confusion.

Paddy