JLG 460SJ Service Manual - Manual (Page 221)

SECTION 3 - CHASSIS & TURNTABLE
3120895 – JLG Lift – 3-169
DTC 521- Oil Pressure Sender/Switch High
Pressure
• Engine Oil Pressure
• Check Condition- Key on, Engine on (or Engine off)
• Fault Condition- For sender types, oil pressure higher
than x psia while engine speed is greater that y RPM.
For switch types, oil pressure is indicating high when
the engine has been stopped for more than n seconds.
• Corrective Action(s)- Illuminate MIL and/or sound audi-
ble warning or illuminate secondary warning lamp,
possibly configure for power derate 1 or low rev limit
• Non-emissions related fault
The ECM can be configured to monitor oil pressure
through a proportional transducer or through a switch. Oil
pressure monitoring is important to prevent engine dam-
age due to low oil pressure resulting in higher friction and
lack of lubrication. In addition, high oil pressure can be
undesirable because it can cause oil to leak past seals
and rings, can be a result of a restriction in the oil flow
path, or can be a sign of a malfunctioning oiling system.
Additionally for normally-open type oil pressure switches,
a high pressure indication while the engine is off is a
symptom of a failed oil pressure switch. The ECM can
monitor oil pressure indication when the engine is
stopped for this failure mode.
For sender types, this fault sets if the engine oil pressure is
higher than x psia and engine speed greater than y RPM
as defined in the diagnostic calibration. For switch types,
this fault sets if the engine oil pressure is indicating high
when the engine is stopped for more than n seconds.
Recommend a power derate and/or low rev limit to help
prevent possible engine damage and reduce oil pressure.