Section 07 ELECTRICAL SYSTEM
Sub-Section 02 (IGNITION SYSTEM)
07-02-12
6. Timer.
7. Multi-Purpose Electronic Module (MPEM).
8. Magneto output (717 engines).
9. Ignition coil output.
NOTE:
To perform verification, a good quality mul-
timeter such as Fluke 73 (P/N 529 022 000) should
be used.
Engine Start/Stop Switch Verification
Disconnect the YELLOW/RED wire of the
start/stop switch. Using an ohmmeter, connect
test probes to YELLOW/RED wire and to ground.
Measure resistance, it must be an open circuit
(switch is normally open). Depress and hold
switch, the ohmmeter should read close to 0
ohm.
Safety Lanyard Switch Verification
If 2 short beeps are not heard when installing the
safety lanyard, refer to ELECTRICAL SYSTEM 07-
06.
The following continuity tests can also be per-
formed using an ohmmeter:
Disconnect switch wires.
Safety Lanyard Removed
Connect test probes to switch BLACK and
BLACK/YELLOW wires. Measure resistance,
there should be no continuity (open circuit).
Connect one test probe to the WHITE/GRAY wire
and the other test probe to the switch terminal.
Measure resistance, it must be close to 0 ohm.
Connect one test probe to the BLACK wire and
the other test probe to the switch ring. Measure
resistance, it must be close to 0 ohm.
Safety Lanyard on Switch
Connect test probes to switch BLACK and
BLACK/YELLOW wires. Measure resistance, it
must be close to 0 ohm.
Timer Verification
The timer is integrated into the MPEM.
Always confirm first that the fuses are in good
condition.
To confirm operation of timer, remove safety lan-
yard from switch. After a 5 seconds delay, de-
press start/stop button once. The timer should
stay on for about 33 seconds (for example,
gauge(s) will be activated) and then turn off.
Rev Limiter Verification
To check engine rev limiter, connect an induction
tachometer (P/N 295 000 100), start engine and
check its maximum speed; it should be at 5900 ±
50 RPM for a 717D engine, 7000 ± 50 RPM for a
717 engine, and 7200 ± 50 RPM for a 787 engine.
Multi-Purpose Electronic Module
(MPEM) Verification
SP, GTS and HX Models
The multi-purpose electronic module testing must
be done with all wires disconnected from circuit.
Otherwise testing equipment (ohmmeter) could
be damaged.
Refer to the following chart for MPEM testing. Al-
ways respect polarity in chart.
-
CAUTION
Whenever replacing a component in ignition
system, check ignition timing.
-
CAUTION
When disconnecting wires, BLACK/RED wire
must never touch solenoid positive termi-
nal. When replacing a MPEM, make sure to
replace it with the right model.
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