Remote PTO Accelerator Position Sensor Circuit

366

TM 9-2320-312-24-2

Troubleshooting Section

The remote accelerator position sensor is used to

provide a throttle position signal to the ECM. Sensor

output is a constant frequency signal with a pulse

Repair: Temporarily connect a test ECM. Ensure

width that varies with the pedal position. This output

that the "PTO Configuration" of the test ECM

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

matches the "PTO Configuration" of the suspect

width modulated signal (PWM) and this output

ECM. Check the ECM operation of the PTO Switch

signal is expressed as a percentage between 3 and

ON Lamp when the test ECM is installed. If the

100 percent.

problem is resolved with the test ECM, reconnect

the suspect ECM. If the problem returns with the

The accelerator position sensor in the cab is

suspect ECM, replace the ECM.

attached directly to the accelerator pedal assembly

and the sensor requires no adjustment.

STOP.

The accelerator position sensor will produce a

i01626696

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

Remote PTO Accelerator

to 90 percent when the accelerator pedal is fully

depressed. The percent of duty cycle is translated

Position Sensor Circuit - Test

in the ECM into an accelerator pedal position of 3

to 100 percent.

SMCS Code: 1913

The accelerator position sensor can be replaced

System Operation Description:

separately from the pedal assembly. An incorrectly

calibrated pedal assembly can not be adjusted.

Use this procedure under the following situation:

The entire pedal assembly must be replaced.

Use this procedure if any of the following diagnostic

If the vehicle is using the ECM dedicated PTO

codes are indicated:

functions, the accelerator position sensor will be

ignored while the engine is in PTO mode and the

30-08 Invalid PTO Throttle Signal (29)

PTO Configuration is programmed to the following

setting:

30-13 PTO Throttle Sensor Calibration (29)

Remote Throttle

Also, use this procedure if the remote accelerator

position sensor is suspected of improper operation.

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

is on. This can be checked through the status

Remote Accelerator Position Sensor

screen on ET.

A remote accelerator position sensor may be

The ECM will not respond to the remote accelerator

used for PTO purposes. The remote accelerator

position sensor when both of the following

position sensor should be connected to the ECM

conditions are met:

connector J1/P1:68. Before the ECM will respond to

the remote accelerator position sensor, the ECM

The PTO On/Off circuit is switched from the OFF

PTO Configuration must be programmed to Remote

position to the ON position.

Throttle, and the PTO On/Off Switch must be in the

ON position. Also, Caterpillar offers the following

The ECM reads the remote accelerator position

recommendation:

sensor above low idle.

The remote accelerator position sensor must be

This prevents the engine from experiencing

powered from the vehicle battery (+12 V).

unexpected acceleration or sudden acceleration

when the PTO On/Off circuit is turned on. The

Therefore, the +12 V version of the accelerator

remote accelerator position sensor must return to

position sensor must be used for the remote

low idle before the ECM will respond. The ECM must

accelerator position sensor, and the +8 V version

also see a transition from the OFF position to the ON

for the accelerator pedal position sensor in the cab.

position in the PTO On/Off Switch in order to allow

the other PTO speed control functions to operate. If

The ECM will not respond to the remote accelerator

the engine is started with the PTO On/Off Switch in

position sensor if 253-02 Check Customer or System

the ON position, the accelerator will respond. The

Parameters (56) is active under some conditions.

response will occur only if the accelerator pedal

Refer to Troubleshooting, "ECM Memory - Test" if

is first returned to the low idle position. The other

253-02 Check Customer or System Parameters (56)

speed control functions will not respond.

is active.