Tach not working after ignition upgrade

3 posts / 0 new
Last post
AnkerB-S
AnkerB-S's picture
Online
Last seen: 2 min 1 sec ago
Joined: 14/11/2019
Tach not working after ignition upgrade

I upgraded the ignition system of my 1987 Supersprint 1700 from a Lucas electronic system to an Aldon Ignitor. I have everything working except the tach.

The tach is a VDO 333/230/147/3 and has three spade poles on the back labeled +, 1, and -. I assume + and - go to 12V+ and ground. My guess is that 1 goes to the negative side of the ignition coil, which also goes to the distributor. When I looked at the wiring diagram for the car there are two white and black wires going from the 1 pole on the tach. One goes to the negative side of the coil and the other into the Lucas module. I suspect that I just need to unplug the old spade connector from the tach and run a wire to the negative pole of the coil and forget about the wires from the electronic ignition, both on the tach and the negative pole of the coil.

I believe that what is preventing the tach from working is the white and black wire that goes to the Lucas module. It is either holding the voltage high or low all the time.

I should mention that I don't want to cut any of the original wires in case someone wants to bring the car back to completely original condition.

Does this make sense?

Thanks/Anker

AnkerB-S
AnkerB-S's picture
Online
Last seen: 2 min 1 sec ago
Joined: 14/11/2019

I decided to give it a try and the tach now works!

Is there any interest in having me do a write up on upgrading from the Lucas electronic ignition?

Anker Berg-Sonne
Stow, Massachusetts

Old fart pretending that age is just a number

1987 Caterham Super 7 1700 Supersprint
2004 Porsche Boxster S
2009 Mercedes CLK 350 Cabriolet

K7 VCT
K7 VCT's picture
Offline
Last seen: 1 hour 43 min ago
Joined: 17/04/2014
Well done

Orange is my new black

Ballistic orange 310s