General Overview

Ignition system with tachometer and timing service instrument socket - 1987

Operation

This breakerless ignition system is equipped with a Hall sensor. (The EZK ignition system is discussed in a separate section.)

When ignition switch 20 is in the start or drive position, ignition coil 5, amplifier 146 and ignition pulse amplifier 147 will be energised (+15).

The amplifier receives ignition pulses via a 3-core shielded cable from the Hall sensor in ignition distributor. The frequency of the pulses is proportional to the engine speed.

The pulses are amplified and adjusted in amplifier 146. A high-tension pulse is generated in the secondary winding each time a pulse breaks the primary circuit of the ignition coil. The high-tension pulse is then supplied to the corresponding spark plug via the distributor.

Tachometer 110 is supplied across fuse 7. The control pulses required for displaying the engine speed are supplied from the ignition pulse amplifier.

Timing service instrument (TSI) socket 73 is intended for a special ignition service instrument and has the following terminals:
1. Positive supply direct from battery 1
2. Earth
3. Solenoid (terminal 50) on starter motor 4
4. Positive supply (+15) from the ignition switch when the latter is in the start or drive position
5. Ignition pulses from ignition pulse amplifier 147
6. Not used


Fault-tracing hints

The ignition system will be energised when the ignition switch is in the drive position.

1. check that terminal 15 on the ignition coil and terminal 4 on the timing service instrument socket are live.
2. Check that terminal 4 on amplifier 146 is live.
3. Check that ignition pulse amplifier 147 is energised (terminal 15) and that the amplifier output delivers ignition pulses (measure at the TSI socket).
4. Tachometer: Check fuse 7 first and check that the supply to it is live. Check that terminal 3 on the circuit board for tachometer 110 is live, and that ignition pulses are being supplied from the ignition pulse amplifier.
5. Check all connectors, cable harnesses and earth connections.