System Operation Description:
Use this procedure under the following situation:
Use this procedure if any of the following diagnostic codes are indicated:
• 30-08 PTO Throttle signal invalid
• 30-13 PTO Throttle out of calibration
Also, use this procedure if the remote accelerator position sensor is suspected of improper operation.
Remote Accelerator Position Sensor
A remote accelerator position sensor may be used for PTO purposes. The remote accelerator position sensor should be connected to the ECM connector J1/P1:68. Before the ECM will respond to the remote accelerator position sensor, the ECM PTO Configuration must be programmed to Remote Throttle, and the PTO On/Off Switch must be in the ON position. Also, Caterpillar offers the following recommendation:
• The remote accelerator position sensor must be powered from the vehicle battery (+12 V).
Therefore, the +12 V version of the accelerator position sensor must be used for the remote accelerator position sensor, and the +8 V version for the accelerator pedal position sensor in the cab.
The ECM will not respond to the remote accelerator position sensor if 253-02 Check Customer or System Parameters is active under some conditions. Refer to Troubleshooting, “ECM Memory – Test” if 253-02 Check Customer or System Parameters is active.
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 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 accelerator position sensor in the cab is attached directly to the accelerator pedal assembly and the sensor requires no adjustment.
The accelerator 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 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 position sensor will be ignored while the engine is in PTO mode and the PTO Configuration is programmed to the following setting:
• Remote Throttle
The ECM is in PTO mode if the PTO On/Off Switch is on. This can be checked through the status screen on the electronic service tool.
The ECM will not respond to the remote accelerator position sensor when both of the following conditions are met:
• The PTO On/Off circuit is switched from the OFF position to the ON position.
• The ECM reads the remote accelerator position sensor above low idle.
This prevents the engine from experiencing unexpected acceleration or sudden acceleration when the PTO On/Off circuit is turned on. The remote accelerator position sensor must return to low idle before the ECM will respond. The ECM must also see a transition from the OFF position to the ON position in the PTO On/Off Switch in order to allow the other PTO speed control functions to operate. If the engine is started with the PTO On/Off Switch in the ON position, the accelerator will respond. The response will occur only if the accelerator pedal is first returned to the low idle position. The other speed control functions will not respond.
Test Step 1. Check the Status for the “PTO Accelerator Sensor”
A. Connect the electronic service tool to the data link connector.
B. Turn the key switch to the On position.
C. Access the status for the “PTO Accelerator Sensor”.
D. While the status for the “PTO Accelerator Sensor” is monitored, operate the PTO throttle from the Low Idle position to the High Idle position.
Expected Result:
The status for the “PTO Accelerator Sensor” is “0%” when the throttle is in the Low Idle position. The status for the “PTO Accelerator Sensor” is “100%” when the throttle is in the High Idle position.
Results:
• OK – The ECM is receiving the signal from the PTO throttle.
Repair: If the ECM is receiving the proper signal, the PTO may be limited by a programmable parameter. Refer to Troubleshooting, “Dedicated PTO Parameters” for more information on parameters that may cause the PTO not to work.
STOP.
• Not OK – The ECM is not receiving the signal from the PTO throttle. Proceed to Test Step 2.
Test Step 2. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the J1/P1 ECM connector, the firewall bulkhead connector and the connector for the remote accelerator position sensor. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.
B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the remote accelerator position sensor:
• J1/P1:3
• J1/P1:68
C. Check the ECM connector (Allen Head Screw) for the proper torque of 6.0 N·m (55 lb in).
D. Check the harness and wiring for abrasion and pinch points from the remote accelerator position sensor to the ECM.
Expected Result:
All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.
Results:
• OK – Proceed to Test Step 3.
• Not OK
Repair: Perform the following diagnostic
procedure:
Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.
Verify that the repair eliminates the problem.
STOP.
Test Step 3. Check the Supply Voltage for the Remote Accelerator Position Sensor
A. Turn the key switch to the ON position.
B. Measure the voltage across J406:A and J406:B.
Expected Result:
The measured voltage is between 11.0 VDC and 13.5 VDC for 12 volt systems. The measured voltage is between 22.0 VDC and 27.0 VDC for 24 volt systems.
Results:
• OK – The voltage is OK. Proceed to Test Step 4
• Not OK – The vehicle wiring or the battery is causing the problem. Repair the wiring or the battery. Replace the wiring or the battery. Perform the repair that is necessary. Verify that the repair has fixed the problem. STOP.
Test Step 4. Check the Duty Cycle of the Remote Accelerator Pedal Position Sensor
A. Turn the key switch to the ON position.
B. Monitor the duty cycle of the PTO throttle sensor on the electronic service tool. Access the following display screen in order:
• “Service”
• “Calibrations”
• “Monitor Throttle Position Sensor”
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 – The remote accelerator position sensor is operating correctly. Proceed to Test Step 5.
• Not OK – The remote accelerator position sensor circuit is not operating correctly. Proceed to Test Step 6.
Test Step 5. Check the Status of the Power Train Data Link
A. Start the engine. While the status for the “PTO Accelerator Sensor” is being monitored, depress the remote PTO accelerator pedal and release the remote PTO accelerator pedal. The throttle position status and the engine should respond to the change in the accelerator pedal position.
B. Go to the “System Troubleshooting Settings” portion of the electronic service tool and turn off the power train data link.
C. While the status of the “PTO Accelerator Sensor” is being monitored, depress the accelerator pedal and release the accelerator pedal. Also depress the accelerator pedal and release the accelerator pedal while the engine response is being monitored.
Expected Result:
The status of the “PTO Accelerator Sensor” and the engine should respond to the change in the accelerator pedal position.
Result 1 The PTO accelerator is functioning properly.
Result 2 The throttle response is limited by a power train data link message.
Results:
• Result 1 – The remote accelerator position sensor is operating correctly. Continue troubleshooting until the original condition is resolved. STOP.
• Result 2 – If the engine responds with the power train data link in the OFF position, but not with the power train data link in the ON position, a component of the power train data link is causing the response problem of the remote accelerator position sensor. Send the truck to the vehicle manufacturer in order to repair the faulty component of the power train data link. STOP.
Test Step 6. Check the Duty Cycle of the Remote Accelerator Position Sensor at the Sensor
Note: Performing certain steps within this procedure requires the use of a multimeter that is capable of measuring a PWM duty cycle.
A. Turn the key switch to the OFF position.
B. Remove the signal wire from J406:C. This is the vehicle harness side of the connector for the accelerator position sensor.
C. Install a breakout T with 3 terminals at the connector J406/P406 for the remote accelerator position sensor.
D. Connect the multimeter probes to terminal C and terminal B of the breakout T.
E. While the duty cycle is being monitored on the multimeter, depress the accelerator pedal and release the accelerator pedal.
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 signal wire into J406:C. The sensor is working correctly. Proceed to Test Step 7.
• Not OK – Leave the PWM probe connected to the breakout T. Insert the signal wire into J406:C. The sensor or the accelerator pedal assembly is faulty. Proceed to Test Step 8.
Test Step 7. Check the Duty Cycle of the Remote Accelerator Position Sensor at the ECM
Note: Performing certain steps within this procedure requires the use of a multimeter that is capable of measuring a PWM duty cycle.
A. Turn the key switch to the OFF position.
B. Remove the wire from P1:68 (Remote Accelerator Position Sensor) from the ECM connector.
C. Connect the multimeter probes between the removed wire and the ECM sensor common or ground.
D. Turn the key switch to the ON position.
E. Use the multimeter in order to display the duty cycle output of the accelerator position sensor. While the duty cycle output of the remote accelerator position sensor is being monitored on the multimeter, move the throttle from the low idle position to the high idle position. Record the results.
F. Turn the key switch to the OFF position.
G. Insert terminal 68 into the P1/J1 ECM connector.
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 – A good signal from the remote accelerator position sensor is reaching the ECM. Verify that the ECM is receiving the proper battery voltage. If the ECM is receiving the proper battery voltage, temporarily connect a test ECM and verify that the problem is resolved. If the problem disappears with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. STOP.
• Not OK – There is a problem with signal wire for the remote accelerator position sensor in the vehicle wiring harness. Proceed to Test Step 9.
Test Step 8. Remove the Remote Accelerator Position Sensor From the Accelerator Pedal Assembly
A. Turn the key switch to the OFF position.
B. Remove the remote accelerator position sensor from the accelerator pedal assembly. Note sensor orientation in the accelerator pedal assembly, and the sensor pigtail routing prior to sensor removal. Thoroughly inspect the pigtail for signs of abrasion.
C. Connect the multimeter that is capable of measuring a PWM duty cycle to terminal C of the breakout T.
D. Turn the key switch to the ON position.
E. Display the duty cycle output of the remote accelerator position sensor while the sensor slot is released. Use a screwdriver to advance the sensor slot to the maximum position. Refer to Illustration 161.
When the sensor is removed from the accelerator pedal assembly the following diagnostic codes may be generated:
• 30-13 PTO Throttle out of calibration
The diagnostic code should disappear when the sensor is properly assembled back into the accelerator pedal assembly.
Expected Result:
When the sensor is removed from the accelerator pedal assembly and the sensor slot is released, the duty cycle is 10 percent or less. When the sensor slot is moved to the maximum position, the duty cycle increases to 90 percent or more.
Results:
• OK – The remote accelerator position sensor is working correctly. Clear any diagnostic codes that were caused by performing this test procedure. Refer to the OEM dealer for correct replacement of the accelerator pedal assembly. STOP.
• Not OK – The remote accelerator position sensor is faulty. Check the accelerator pedal assembly in order to ensure that the accelerator pedal assembly is not causing damage to the sensor. If the accelerator pedal assembly is causing damage to the sensor, refer to the OEM dealer for correct replacement of the accelerator pedal assembly. STOP.
Test Step 9. Route the Supply Bypass Wires to the Remote Accelerator Pedal Position Sensor
A. Turn the key switch to the OFF position.
B. Remove P1:66 remote accelerator position sensor from the ECM connector P1.
C. Remove terminal C (Accelerator Pedal Position) from the connector for the remote accelerator position sensor.
D. Route new wiring from the ECM to the remote accelerator position sensor.
E. Turn the key switch to the ON position.
F. Check the duty cycle of the remote accelerator position sensor with the electronic service tool while the accelerator pedal assembly is being moved over the full range.
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 – The wiring from the ECM to the accelerator position sensor appears faulty. Permanently install new wiring. Verify that the repair eliminates the problem. STOP.
• Not OK – Double check the wiring, the ECM vehicle harness connector J1/P1 and the sensor connector. If a problem still exists, restart the test procedure. STOP.
