Oshkosh JLG 1500SJ, Service And Maintenance Manual

Page: 212 / 706

SECTION 3 - CHASSIS & TURNTABLE
3-162 – JLG Lift – 3121262
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.
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 pres-
sure 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.
Normally Closed Switch
BLUE
BLACK/GREEN
19
1
2
• Key-On, Engine Off
• System Mode= “Stopped”
Does DTC 524
reset ?
Intermittent Problem
No
• Key Off
• Disconnect harness from Oil Pressure switch
• Check continuity through switch to ground.
Yes
Is switch open?
• Oil Pressure circuit shorted-to-ground in harness
• Faulty ECM
• Faulty Oil Pressure Switch (short circuit)
• Faulty engine oiling system (verify with
mechanical gauge)
No
Yes