Service Manual Instruction Manual

SECTION 3 - CHASSIS & TURNTABLE

3121171 – JLG Lift – 3-189

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

TAN/ORANGE

GREEN/RED

PURPLE/BLUE

BLACK/GREEN