JLG 600A_AJ Service Manual - Manual (Page 130)

SECTION 3 - CHASSIS & TURNTABLE
3-80 – JLG Lift – 3121201
IGNITION COIL
The electronic ignition system uses a coil pack with one
ignition coil for each two cylinders in the engine. Each cyl-
inder is paired with its opposing cylinder in the firing order,
so that one cylinder on compression fires simultaneously
with the opposing cylinder on exhaust. The spark that
occurs in the cylinder on the exhaust stroke is referred to
as a "waste spark."
The primary coils in the coil pack are triggered by the
"Ignition Coil Feed #1" and "Ignition Coil Feed #2" Signals
from the ECM.
ENGINE CONTROL MODULE (ECM)
The ECM is responsible for maintaining proper spark and
fuel injection timing for all operating conditions. To provide
optimum operation and emissions, the ECM monitors the
input signals from the following components in order to
calculate spark timing:
• Engine coolant temperature (ECT) sensor
• Intake air temperature (IAT) sensor
• Throttle position sensor
• Crankshaft position sensor