Accelerator Pedal Position Sensor

144

TM 9-2320-312-24-2

Troubleshooting Section

91-13 Throttle Sensor Calibration (28)

The ECM is in PTO mode if the "PTO On/Off Switch"

is on. This can be checked with the Caterpillar

41-03 8 Volt Supply Above Normal (21)

Electronic Technician (ET). Refer to Troubleshooting,

"PTO Switch Circuit - Test" for testing if the PTO

41-04 8 Volt Supply Below Normal (21)

is being used.

Also, use this procedure if the accelerator pedal

position sensor is suspected of improper operation.

Accelerator Pedal Position Sensor

The accelerator pedal position sensor is used to

provide a throttle position signal to the ECM. Sensor

output is a constant frequency signal with a pulse

width that varies with the pedal position. This output

signal is referred to as either a duty cycle or a pulse

width modulated signal (PWM) and this output

signal is expressed as a percentage between 3 and

100 percent.

The pedal mounted accelerator pedal position

sensor is attached directly to the accelerator pedal

assembly and the pedal mounted accelerator pedal

position sensor requires no adjustment.

The accelerator pedal position sensor will produce

a duty cycle of 10 to 22 percent at low idle and 75

to 90 percent when the accelerator pedal is fully

depressed. The percent of duty cycle is translated

in the ECM into an accelerator pedal position of 3

to 100 percent.

The accelerator pedal position sensor is powered by

the ECM supply voltage (+8 VDC) from connector

P1:4 to terminal "A" of the accelerator pedal position

sensor connector. The accelerator pedal position

sensor can be replaced separately from the pedal

assembly. An incorrectly calibrated pedal assembly

can not be adjusted. The entire pedal assembly

must be replaced.

If the vehicle is using the ECM dedicated PTO

functions, the accelerator pedal position sensor will

be ignored while the engine is in PTO mode and

the "PTO Configuration" is programmed to one of

the following parameters:

Remote Switches

Remote Throttle

Note: In the cab switches configuration, the cab

accelerator pedal can be used in order to control

the engine rpm for the PTO operation. The cab

accelerator pedal can also be ignored in the "Cab

Switches" PTO configuration. Programming of

customer parameters is required in order to ignore

the cab accelerator pedal in the "Cab switches"

configuration.