JLG 600SC_660SJC Service Manual - Manual (Page 190)

SECTION 6 - TURNTABLE
6-44 – JLG Lift – 3121157
DTC 337- Loss of Crank Input Signal
• Crankshaft Position sensor
• Check Condition- Key On, Engine On
• Fault Condition- Loss of crankshaft position signal
while valid camshaft position signals continue for x
number of cam pulses as defined in the diagnostic cal-
ibration
• Corrective Action(s)- Illuminate MIL and/or sound audi-
ble warning or illuminate secondary warning lamp
• Emissions related fault
The crankshaft position sensor is a magnetic sensor (vari-
able reluctant/magnetic pick-up or halleffect) installed in
the engine block adjacent to a ¡§coded¡¨ trigger wheel
located on the crankshaft. The sensor-trigger wheel com-
bination is used to determine crankshaft position (with
respect to TDC cylinder #1 compression) and the rota-
tional engine speed. Determination of the crankshaft posi-
tion and speed is necessary to properly activate the
ignition, fuel injection, and throttle governing systems for
precise engine control.
The ECM must see a valid crankshaft position signal while
running. If no signal is present while x cam pulses con-
tinue the fault will set. The engine typically stalls or dies as
a result of this fault condition due to the lack of crankshaft
speed input resulting in the inability to control ignition tim-
ing.
DTC 337- Loss of Crank Input Signal (continued)
Diagnostic Aids
• Check that crankshaft position sensor is securely con-
nected to harness
• Check that crankshaft position sensor is securely
installed into engine block
• Check crankshaft position sensor circuit wiring for
open circuit
WHITE/PURPLE
WHITE/PURPLE
2
1 PURPLE/WHITE
PURPLE/WHITE