Connecting 100mm VDO Tacho to v8 waisted spark

ie this type



de wired the dizze so need to hook this up to range rover waised spark ( 4 coil units ) and switched from my ecu ( on the earth ).

Anyone know how to do this ( I have emailed etb as per there instructions ) just thought I would ask the collective .

Option 2 is to feed from my Vems ECU

Many thanks

Agriv8

if my sums are right, you connect any one coil and set rev counter to "2 cylinder" - just one snag as I reckon it only allows 4-6-8 selection.

so plan 2 is to connect a diode from any two coils to the rev counter and select "4 cylinder" or 4 diodes from all 4 coils and select "8 cylinder"

note: coils are wired as you have them and the diodes are in addtion as shown

as show below - the orientation of the diodes is critical!

plan 3 use vems - this may need a voltage converter from 0-5V to 0-12 V.


so you know I am not making this up;

[Edited on 14/4/09 by 02GF74]
Rescued attachment rev.JPG

Seems Vems is the easy option as the ecu and the tacho is only 3 inches apart I can use one of the p259 ports and get that to switch the 12 v signal with a 1 k resistor as shown here.



I will get down to maplin at dinner and give it a go.

thanks for your assistance

Agriv8

yep, tha'tll be simpler ... but you didn;t say plan2 was the main plan.

Ahh thats what my project manager keeps teeling me.

Plan 1 is always the comfotable easy one.

Plan 2 usually means I have to go and do some work and learn somthing ( but usually ends up presenting itself as the best option as above )

Plan 3 is left for defalecting as much flack as possible somewhere else

Regards

Agriv8