JLG 510AJ Service Manual - Manual (Page 194)

SECTION 3 - CHASSIS AND TURNTABLE
3-152 – JLG Lift – 3121181
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.
2
16
13
12
1
5V_ext
Vs=+5 VDC
5V_rtn
TPS1
TPS SER +
+
-
Motor
DBW-
DBW+
ECM
H-Bridge
19
TPS SER -
Serial
xmitter
Electronic Throttle Actuator w/Analog Position Feedback Electronic Throttle Actuator w/Serial Position Feedback