Test Step 9. Check the Duty Cycle of the Accelerator Pedal Position Sensor at the ECM

149

TM 9-2320-312-24-2

Troubleshooting Section

Expected Result:

The duty cycle is between 10 and 22 percent with

the accelerator pedal assembly in the Low Idle

position, and the duty cycle is between 75 and 90

percent with the accelerator pedal assembly in the

High Idle position.

Results:

OK Reinsert the wire (terminal "C") into the

OK A good signal from the accelerator pedal

vehicle harness connector. The accelerator pedal

position sensor is reaching the ECM. Verify that

position sensor is working correctly. Proceed to

the ECM is receiving the proper battery voltage. If

Test Step 9.

the ECM is receiving the proper battery voltage,

temporarily connect a test ECM and verify that the

Not OK Leave the PWM probe connected to

problem is resolved. If the problem disappears

with the test ECM, reconnect the suspect ECM.

the breakout T. Insert the wire (terminal "C") into

If the problem returns with the suspect ECM,

the vehicle harness connector. The accelerator

replace the ECM. STOP.

pedal position sensor or the accelerator pedal

assembly is faulty. Proceed to Test Step 10.

Not OK There is a problem with signal wire

Test Step 9. Check the Duty Cycle of the

for the accelerator pedal position sensor in the

Accelerator Pedal Position Sensor at the

vehicle wiring harness. Proceed to Test Step 11.

ECM

Test Step 10. Remove the Accelerator

Pedal Position Sensor from the

Note: Performing certain steps within this procedure

Accelerator Pedal Assembly

requires the use of a multimeter that is capable of

measuring a PWM duty cycle.

A. Turn the ignition key switch to the OFF position.

B. Remove the accelerator pedal position sensor

B. Remove the wire for the accelerator pedal

from the accelerator pedal assembly. Note

position sensor P1:66. You may be required to

sensor orientation in the accelerator pedal

disconnect ECM connector P1 in order to remove

assembly, and the sensor pigtail routing prior to

the terminal for the signal input of the accelerator

sensor removal. Thoroughly inspect the pigtail

pedal position sensor.

for signs of abrasion.

C. Connect the multimeter probes between the

C. Connect the multimeter that is capable of

removed wire and P1:5 (Accelerator/Switch

measuring a PWM duty cycle to terminal "C" of

Sensor Common).

the breakout T.

D. Reconnect ECM connector P1 to the ECM.

D. Turn the ignition key switch to the ON position.

E. Turn the ignition key switch to the ON position.

E. Display the duty cycle output of the accelerator

pedal position sensor while the sensor slot is

F. Use the multimeter in order to display the

released. Use a screwdriver to advance the

duty cycle output of the accelerator pedal

sensor slot to the maximum position. Refer to

position sensor. While the duty cycle output

Illustration 26.

of the accelerator pedal position sensor is

being monitored on the multimeter, move the

When the sensor is removed from the accelerator

accelerator assembly from the Low Idle position

pedal assembly, the following diagnostic code

to the High Idle position. Record the results.

may be generated:

91-13 Throttle Sensor Calibration (28)

G. Turn the ignition key switch to the OFF position.

H. Insert P1:66 into the ECM vehicle connector P1.

This is normal. The diagnostic code should

disappear when the sensor is properly

assembled back into the accelerator pedal

assembly.