https://www.clubford.ro/documente/ma...01981-1990.pdf
Page 226 is your diagram. Assuming your is after 1986:
Part 138 is the suppressor
Part 133 is the speed sensor relay/module
Part 68 is the Fuel injection relay
Part 102 is the instrument clustor (tacho)
It looks like the speed sensing relay uses the flyback from the negative of the ignition coil to enable the fuel injection relay. The flyback voltage signal goes via the suppressor to the speed sensing relay.
Rob,