Oshkosh JLG 1500SJ, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3-196 – JLG Lift – 3121262
DTC 9999- Throttle Actuator Failsafe Spring
Failure
• Throttle Actuator
• Check Condition- Key Off, Engine Stopped
• Fault Condition- When the key is off (or the actuator is
unpowered), the ECM is expecting the failsafe spring in the
actuator to return the throttle position to near 0%. If the
throttle does not reach this position when the actuator is
powered, a fault is generated.
• Corrective Action(s)- Illuminate MIL, sound audible warn-
ing or illuminate secondary warning lamp. Govern the
engine speed to a forced idle speed.
• Non-emissions related fault
The throttle actuator has a return spring that causes the throt-
tle to move to a near 0% position when powered off. This
causes the engine to shutdown following a key off. If the ECM
detects the throttle position to be above x volts when the key
is off (as determined by the diagnostic calibration), it will
power up the actuator and attempt to drive it to a zero posi-
tion. This should ensure that the engine is stopped.
This fault will set if the throttle does not return to a near 0%
position with the key is off.
Diagnostic Aids
• Disconnect the throttle actuator from the wire harness.
Remove the throttle actuator from the engine and manu-
ally move it. Verify that the internal spring forces the throt-
tle back to near 0% position.
• Inspect the throttle arm or fuel rack on the fuel pump. Ver-
ify that it is not stuck.
PINK/WHITE
4
3
5
1
2
TAN/ORANGE
GREEN/RED
PURPLE/BLUE
BLACK/GREEN