Rev counter input

[Mikey UC]

Does anyone know where the connection is to the rev counter on a crossflow wiring loom ?

I have a new Omex ecu with an output lead to the tacho but having problems trying to trace the wiring back to the tacho input.

 

Many thanks

[Jonathan Kay]

I've got the 1988 Assembly Guide. This includes a colour-coded but mostly-unlabelled wiring diagram. Send me a BlatMail if you'd like a copy.

 

Jonathan

[Mankee]

Mikey, I don't know how your old Crossflow ignition worked (coil perhaps?) or how your K-series/Weber conversion currently provides spark, but my EU2 K-series with distributor bolted to the end of the inlet cam has its tacho feed straight off the coil to the rev counter.

 

You could run a temporary wire from the Omex to your tacho to check that it works properly, as my Emerald wouldn't drive my old rev counter for whatever reason, so reverted back to the feed from the coil.

[Nigel Riches]

Mikey, my car is 1982 vintage and wired for a x flow, the tacho signal was from the coil, a brown + white trace wire to the tacho, white is the supply from the ignition switch, and green + purple to the distributor.

If you have a Smiiths tacho you may find a a "bullet" connector on the rear, this is the input signal wire, there will also be a green wire right next to the input wire, and a black wire to ground from the instrument case, the ecu tacho out signal (using Emerald K3) connects to the brown + white wire, either in the engine bay, easy route, or on the rear of the instrument, difficult route, down which I went this weekend.

Please check the your wiring, it may be different to mine, but hopefully this has been helpful. Regards, Nigel.

[Molecular--Bob]

I have just redone mine on an ex-crossflow, I made notes as i was removing the old loom, but can't remember the colour at the moment. Originally i used one of the coil wires as Nigel notes, and when I redid it I traced this wire in the old loom to the connector block for the ignition module under the scuttle and connected at this point. If your ecu is under the bonnet then the coil lead is the easiest. I used the positive coil lead as the always live on cranking trigger for my main ecu power relay.

 

I will check my wire colours tonight if you still need confirmation.

[Mikey UC]

Cheers Jonathan – I have a wiring diagram,( but I’m struggling to read it.)

 

On the crosflow I had a Webcon distributerless coil pack which I am also using for the K Series. I am using a white 12v cable ( which I’m pretty sure was the old coil supply) to power the coil pack, and I have earthed the coil pack directly back to the chassis.

 

Next to the white cable termination there is also a white cable with a black line running along it, I guess this was the negative terminal for the coil, which I was going to use for my negative / earth but decided not to as it was showing about 5v back to earth.

 

I'll try to find the brown / white trace white in the engine bay tonight and go from there,

 

Cheers gents.

 

[Molecular--Bob]

My notes say black and white coil connection was used for the tacho out from my ecu. I will check on the car to confirm