JLG 660SJ Service Manual - Manual (Page 122)

SECTION 3 - CHASSIS & TURNTABLE
3-72 – JLG Lift – 3121202
Megajector Diagnostic Code Descriptions
The following diagnostic codes are specific to the mega-
jector. They will be displayed on the analyzer if the JLG
Control System senses a fault dealing with the megajec-
tor. Refer to Section 6 - JLG Control System for more infor-
mation concerning the Control System.
DTC 353 - Megajector delivery pressure higher than
expected. This code will set if the difference between the
Megajector actual pressure and the Megajector com-
manded pressure is greater than 4.00 inches (10.1 cm) of
H
2
O.
a. Fuel Supply - Check fuel supply pressure at the
megajector inlet fitting. Fuel supply pressure on
LPG applications should be between 3-5" (7.6-
12.7 cm) H
2
O.
b. Lockoff Solenoid - Check the lockoff to make
sure it is sealing when closed. If it is not com-
pletely sealing, it could allow pressure creep in
the fuel system.
c. Reference Line - Make sure the reference line is
in place between the Megajector and the carbu-
retor balance port. Make sure the hose is not
kinked or restricted in any way and has no holes
in it.
d. Regulator - Observe the regulator with the
engine running to see if it is icing up. If it’s icing
up, refer to Engine Cooling System below.
e. Engine Cooling System - Make sure the engine
cooling system is operating properly and there
are no air locks in the system. Make sure the
engine is operating at the proper temperature.
Check the coolant hoses at the regulator and
make sure they are both warm to verify proper
coolant circulation.
If the fuel system is operating properly, the Megajector
has an internal failure and must be replaced.
DTC 354 - Megajector delivery pressure lower than
expected. This code will set if the difference between the
Megajector actual pressure and the Megajector com-
manded pressure is less than -4.00 inches (10.1 cm) of
H
2
O.
a. Fuel Supply - Check fuel supply pressure at the
megajector inlet fitting. Fuel supply pressure on
LPG applications should be between 3-5" (7.6-
12.7 cm) H
2
O.
b. Fuel System Hoses - Make sure all fuel system
hoses are in good condition. They should be
clamped tight, free from kinks with no cuts,
pinches, etc.
c. Lockoff Solenoid - Check the lock off to make
sure it is opening properly. If it is not opening
completely, it could cause low fuel pressure.
d. Reference Line - Make sure the reference line is
in place between the Megajector and the carbu-
retor balance port. Make sure the hose is not
kinked or restricted in any way and has no holes
in it.
e. Regulator - Observe the regulator with the
engine running to see if it is icing up. If it’s icing
up, refer to Engine Cooling System below.
f. Engine Cooling System - Make sure the engine
cooling system is operating properly and there
are no air locks in the system. Make sure the
engine is operating at the proper temperature.
Check the coolant hoses at the regulator and
make sure they are both warm to verify proper
coolant circulation.
If the fuel system is operating properly, the Megajector
has an internal failure and must be replaced.
DTC 355 - Megajector comm. lost. This codes will set if
the communication (CAN link) between the Megajector
and the EPM is not present.
a. CAN Circuits - Check CAN circuits for continuity
and shorts to power or ground and for proper
connections.
If the CAN circuits are ok and all wiring connections are
good, the Megajector has an internal failure and must be
replaced.
DTC 361 - Megajector voltage supply high.
a. Voltage - Check battery voltage. If the voltage at
the battery is greater than 18 volts, either the
charging system or the megajector is faulty.