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Hi all.
I wonder if any of you can shed any light on how to make my S40 ecu work with a rev counter from the 1980's ?
Originally the rev counter took its signal from one of the coil negative wires but apparently the S40 only has a digital tacho output.
Thats all I know.. so far.
Any ideas or suggestions ?
Cheers.
Skel.

You could take it from the coil negative.....

If that cannot work, more details of your install are required.

Try this - works on 70 / 80's era cars.....

Here's what I did many years ago on my Mk2 Golf:

http://clubgti.com/showthread.php?16615 ... ost1516418

Cheers guys.
Slightly confused though.
On this diagram it takes a neg from both coils but on my bike it only took a neg from one of the coils to drive the revcounter.
If I do it as in the diagram will my revcounter read double due to twice as many pulses ?

It will if yours only needed a single coil feed originally. The Dyna2000 always gave the option of 1 pulse or twin to drive the varied tacho requirements.

Cheers Katana (good name)
I'm using Dyna 2.2 ohm grey coils on my bike which should be compatible with the S40.
If I take one coil neg I wont need a diode... will I ?
Just tried to upload a photo of my bike but apparently my 'entity' is too large..
Skel

I think you may need the D3 Zener diode to stop reverse voltage spikes but i'm no guru!
The name......I had one GSX1000SZ as a drag bike a few moons ago.

Well it looks like I dont have to bother with any of that stuff as it seems to work fine.
strange though as it doesn't work when I use the 'test circuits' function.
but it works and seems to read spot on..

The test circuits won't work the rev counter, it's for testing auxiliary components only.
Glad to see you're up and running.