on the ignition amplifier (also referred to as the module or the igniter) is
vital to the operation of the ignition system and is often overlooked as an
area for potential problems.
connection , if not in good condition, can cause a reduction in the primary
current that will effect the current limiting (or dwell control) circuit. It
is therefore vital that this important connection is tested and rectified if
it is found to be outside of its operational limits. An earth return circuit
can only be tested while the circuit is under load and this therefore makes
continuity testing to earth with a multimeter inaccurate. As the coil's
primary circuit is only complete during the dwell period, this is the time
that the voltage drop should be monitored.
'flatter' the resultant waveform the better. A waveform with virtually no
rise, shows that the amplifier/module has a perfect earth. If the 'ramp' is
too high, another earth wire can be soldered in parallel with the original
wire and secured to a good earthing point.
of the ignition amplifier is to switch the relatively high primary current of
approximately 8 to 10 amps to earth, when the component receives a signal from
either the pick-up or Electronic Control Module (ECM). The earth path on this
circuit plays a very important role in maintaining the correct operation of
the primary ignition circuit.
path is often overlooked as a problem area, the condition of the wiring and
connections to ground is important. However, tests may indicate good
continuity under these conditions (no load), but this test does not
demonstrate the circuit's ability to perform while operational.
A volt drop
check is the only option available if the earth's path back to the battery is
to be correctly assessed. The length of the ramp is determined by the dwell
angle and will expand as the engine speed increases.