JLG 450A_AJ Series II Service Manual - Manual (Page 171)

SECTION 3 - CHASSIS & TURNTABLE
3121290 – JLG Lift – 3-131
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 audible
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 damage 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 malfunc-
tioning oiling system.
For normally-open type oil pressure switches, a high pressure
indication while engine is off is a symptom of a failed oil pres-
sure switch. The ECM can monitor oil pressure indication when
engine is stopped for this failure mode.
For sender types, this fault sets if engine oil pressure is higher
than x psia and engine speed greater than y RPM as defined in
diagnostic calibration.
For switch types, this fault sets if engine oil pressure is indicat-
ing high when engine is stopped for more than n seconds.
Recommend a power derate and/or low rev limit to help pre-
vent possible engine damage and reduce oil pressure.