JLG 450A_AJ Series II Service Manual - Manual (Page 239)

SECTION 3 - CHASSIS & TURNTABLE
3121180 – JLG Lift – 3-189
DTC 604- Microprocessor Failure - RAM
• Engine Control Module- Random Access Memory.
• Check Condition- Key on.
• Fault Condition- Internal ECM microprocessor memory
access failure.
• Corrective Action(s)- Illuminate MIL and/or sound audi-
ble warning or illuminate secondary warning lamp, dis-
able adaptive fueling correction for remainder of key
cycle, recommend power derate 2 and low rev limit to
reduce possible engine damage and/or overspeed
condition.
• Non-emissions related fault
Random Access Memory is located in the microprocessor
and can be read or written at any time. Data stored in RAM
include DTCs (when fault configuration is set to “Battery
Power Retained"), adaptive fuel learn tables, octane adap-
tation table, misfire adaptation tables, and closed loop fuel
multipliers. The ECM has checks that must be satisfied
each time an instruction is executed.
This fault sets if the ECM detects a problem accessing or
writing information to RAM and should be configured to
set a power derate 2 and low rev limit to reduce possible
engine damage and reduce possibility of an overspeed
condition. If this fault sets, the ECM will reset itself and log
the code. This fault should be erased by a technician after
diagnostics are performed. The fault should be configured
to never forget and will not self-erase.