Use this procedure under the following situation:
Use this procedure to determine that the vehicle wiring and the Engine Control Module (ECM) are functioning properly for the features of dedicated PTO.
The following background information is related to this procedure:
INPUT 1
P1-56 Input 1 is used for the circuit for the PTO on/off switch when the PTO configuration is programmed to "Cab Switches", to "Remote Switches", or to "Remote Throttle".
When the PTO on/off switch is on, the ECM will be in dedicated PTO mode.
When the ECM is in the dedicated PTO mode the PTO Top Engine Limit (TEL) is activated. The engine may proceed directly to the PTO engine rpm set speed if the parameter is programmed. If a PTO switch on lamp is connected to the P1-30 output 1, the PTO switch on lamp will turn on whenever the PTO on/off circuit is on.
If the problem is with undetermined PTO kickouts, use the following procedure:
Operate the vehicle in PTO mode.
After the kickout, review the status parameter on Caterpillar Electronic Technician (ET). The status parameter indicates the cause of the kickout. This must be performed before the ignition keyswitch is turned off. It is important to remember that the parameter will only indicate the last kickout since the ECM has been powered by the ignition key switch.
This parameter is blank when the ECM is first powered up. If this parameter is blank "Not Kicked Out" is indicated. This parameter remains blank until the ECM detects the use of the PTO mode. Also, this parameter remains blank until the ECM detects the disengagement of PTO mode. Refer to Table 1 in order to interpret the status parameter.
PTO interlocks may also be connected in series with the PTO on/off switch. The interlocks are intended to prevent the PTO on/off circuit from activating unless certain conditions are met.
INPUT 2
P1-58 input 2 is used for the PTO set switch when the "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle". The PTO set switch can also be used to increase engine rpm.
INPUT 3
P1-60 input 3 is used for the PTO resume switch when the "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle". The PTO resume switch can also be used to decrease engine rpm.
The PTO Configuration Is Set To Cab Switches.
When the "PTO Configuration" is programmed to "Cab Switches" and the PTO on/off switch is on, the following circuits can be used to interrupt a set rpm:
- Cruise control set/resume switch
- Service brake pedal position switch 1
- Service brake pedal position switch 2
- Clutch pedal position switch
- Neutral switch
- Cruise control pause switch
When the "PTO Configuration" is programmed to "Cab Switches" and the PTO on/off switch is on, the accelerator pedal position sensor that is located in the cab can be limited to one of the following settings by using the "PTO Cab Throttle RPM Limit" parameter:
- Low idle
- PTO top engine limit
- Top engine limit
The "PTO Configuration" Is Programmed To "Remote Switches" or "Remote Throttle".
When the "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle" and the PTO on/off switch is on, the following circuits are ignored:
- Service brake pedal position switch 1
- Service brake pedal position switch 2
- Clutch pedal position switch
- Neutral switch
- Accelerator pedal position sensor
- Cruise control set/resume switch that is located in the cab
A remote accelerator pedal position sensor is connected to P1-68 input 8 when the "PTO Configuration" is programmed to "Remote Throttle".
Note: The wiring for your particular application may be slightly different. The circuits for the sensor common are used interchangeably by the OEM of the vehicle. The following circuits are common within the ECM:
- P1-18 (sensor common 1)
- P1-3 (sensor common 2)
- P1-5 (AP sensor/switch sensor common)
| Table For The "PTO Kickout" Status Screen On Cat ET | ||
|---|---|---|
| Cat ET | Meaning or Possible Cause | Troubleshooting |
| "No Engine Speed" | Intermittent engine speed signal or lost engine speed signal. | Refer to Troubleshooting, "Engine Speed - Test". |
| "Switch Turned Off" | The PTO on/off switch is turned off or the switch circuit has an open circuit condition. | Proceed with this test procedure. |
| "Cruise Control PAUSE Switch" | The cruise control pause switch is depressed or there is an illegal message on the J1939 data link. | Refer to Troubleshooting, "Data Link - Test". |
| "Brake Pedal Depressed" | The service brake pedal is depressed or the circuit for the service brake switch has an open circuit condition. | Refer to Troubleshooting, "Speed Control (Auxiliary) - Test". |
| "Clutch Pedal Depressed" | The clutch pedal is depressed or the circuit for the clutch pedal position switch has an open circuit condition. Also, the switch could be incorrectly adjusted. | |
| "Vehicle Speed ≥ Limit" | The vehicle speed has exceeded the speed that is programmed into the "PTO vehicle speed limit" parameter or the vehicle speed signal is erratic or intermittent. | Refer to Troubleshooting, "Vehicle Speed - Test" if a problem with the signal exists. |
| "Neutral" | The transmission is not in neutral or the transmission neutral switch circuit has an open circuit condition. | Refer to Troubleshooting, "Speed Control (Auxiliary) - Test". |
| "Not Kicked Out" | The PTO has not been enabled since the ECM has been powered up. | Operate the vehicle in the PTO mode in order to create the problem again. |
 | |
| Illustration 1 | g00644420 |
Typical circuit schematic for "Cab Switches" configuration The return wire may be connected to P1-3, P1-5, or P1-18. | |
 | |
| Illustration 2 | g00644427 |
Typical circuit schematic for "Remote Switches" configuration The return wire may be connected to P1-3, P1-5, or P1-18. | |
 | |
| Illustration 3 | g00644448 |
Typical circuit schematic for "Remote Throttle" configuration The return wire may be connected to P1-3, P1-5, or P1-18. | |
Test Step 1. Use Cat ET to Check the Programming of the Parameter "Dedicated PTO Parameters"
- Connect Cat ET to the data link connector.
- Turn the ignition key switch to the ON position.
- Access the "Dedicated PTO Parameters" on Cat ET. Note the programming of the parameter "PTO Configuration".
Expected Result:
The "PTO Configuration" is programmed to "Cab Switches", to "Remote Switches", or to "Remote Throttle".
Results:
- OK - The "PTO Configuration" is programmed. Proceed to Test Step 2.
- Not OK - The Dedicated PTO features are not programmed for this engine. If PTO operation is desired, the "PTO Configuration" must be programmed to "Cab Switches", to "Remote Switches", or to "Remote Throttle".STOP
Test Step 2. Determine the Configuration of the PTO Electrical System
- From the programming of the parameter for the "PTO Configuration", review the configuration of the PTO electrical system in order to determine the method of installation of the wiring. Talk to the driver about the operation of the PTO.
- Check the cab glove box for any information regarding the installation of the PTO. It is important to understand the location and the function of the interlock switches for the PTO.
- Contact the installer of the components that are used for the PTO, if necessary.
- Determine the schematic that most closely matches the installation. Review the schematics in this procedure for each of the options for the specific "PTO Configuration" of the truck.
- Record the "PTO Configuration".
Expected Result:
The requirements for the installation and the application have been reviewed.
Results:
- OK - The requirements for the installation and the application have been reviewed. Proceed to Test Step 3.
Test Step 3. Inspect the Electrical Connectors and the Wiring
 | |
| Illustration 4 | g01152436 |
P1 ECM connector (P1-3) Input sensor common number 2 (P1-5) AP sensor/switch sensor common (P1-22) Clutch pedal position switch (P1-30) Output number 1 (P1-35) Set (P1-44) Resume (P1-45) Service brake pedal position switch (P1-56) Input number 1 (P1-58) Input number 2 (remote PTO set) (P1-60) Input number 3 (remote PTO resume) (P1-68) Input number 8 | |
- Turn the ignition key switch to the OFF position.
- Thoroughly inspect the J1/P1 ECM connector, the firewall bulkhead connectors, and any connectors that are used by the PTO.
Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the connections for the PTO.
Refer to Illustration 4.
- Check the allen head screw on each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Check the harness and wiring for abrasion and for pinch points from the switch to the ECM.
Expected Result:
All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.
Results:
- OK - The harness and connectors appear to be OK. Proceed to Test Step 4.
- Not OK - There is a problem with the connectors and/or wiring.
Repair: 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 4. Use Cat ET to Check the Circuit for the PTO On/Off Switch
- Turn the ignition key switch to the ON position.
- For the input 1 (PTO on/off switch), access the Cat ET status screens that display the following status parameters:
- "PTO Config"
- "PTO On/Off Switch"
- "PTO Config"
- Verify that each of the interlocks for the PTO are set. Then, while the Cat ET status screen is being monitored move the PTO on/off switch to the ON position and move the PTO on/off switch to the OFF position.
An example of an interlock for the PTO would be a parking brake that is intended to allow the PTO to control the engine under specific conditions.
Expected Result:
Result 1 The status of the PTO on/off switch on Cat ET changes from "OFF" to "ON" when the PTO on/off switch is turned to the OFF position and the ON position, but the set/resume switch is not operating correctly.
Result 2 The status of the PTO on/off switch on Cat ET changes from "OFF" to "ON" when the PTO on/off switch is turned to the OFF position and the ON position. However, the remote accelerator is not operating correctly.
Result 3 The status of the PTO on/off switch on Cat ET does not change from "OFF" to "ON" when the PTO on/off switch is turned to the OFF position and to the ON position.
Results:
- Result 1 - The status of the PTO on/off switch correctly changes but the set/resume switch is not operating correctly. Proceed to Test Step 5.
- Result 2 - The status of the PTO on/off switch correctly changes but the remote accelerator is not operating correctly.
Repair: Perform the following diagnostic procedure: Troubleshooting, "Sensor Signal (PWM) - Test"
STOP
- Result 3 - The status of the PTO on/off switch does not change. Proceed to Test Step 6.
Test Step 5. Use Cat ET to Check the Status of the Set/Resume Input
Note: The set/resume input increases the engine rpm and the set/resume input decreases the engine rpm.
- Find the PTO set switch. If the "PTO Configuration" is programmed to "Cab Switches", the cruise control set/resume switch will be used. If the "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle", a dedicated PTO set switch will be used.
The "PTO Configuration" is programmed to "Cab Switches".
Look at the status for the "Cruise Control Set/Resume Switch" parameter on Cat ET. The parameter is located on the same status screen as the idle switch.
- Monitor the status screen of Cat ET. Perform the following procedure in order:
- Put the cruise control set/resume switch in the Set position.
- Release the cruise control set/resume switch from the Set position.
- Put the cruise control set/resume switch in the Resume position.
- Release the cruise control set/resume switch from the Resume position.
The "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle".
View the status parameter on Cat ET for the "Remote PTO Set Switch" and for the "Remote PTO Resume Switch".
- Put the cruise control set/resume switch in the Set position.
- While the status screen of Cat ET for the switch is being monitored, perform the following procedure in order:
- Put the remote PTO set/resume switch in the Set position.
- Release the remote PTO set/resume switch from the Set position.
- Put the remote PTO set/resume switch in the Resume position.
- Release the remote PTO set/resume switch from the Resume position.
- Put the remote PTO set/resume switch in the Set position.
Expected Result:
When the "PTO Configuration" is programmed to "Cab Switches", the status parameter for the cruise control set/resume switch on Cat ET behaves in the following manner:
- The status of the cruise control set/resume switch will display "OFF" when the set switch is released.
- The status of the cruise control set/resume switch changes from "OFF" to "ON" when the switch is moved to the SET position.
- The status of the cruise control set/resume switch changes from "OFF" to resume switch "ON" when the resume switch is moved to the RESUME position.
When the "PTO Configuration" is programmed to "Remote Switches" or to "Remote Throttle", the status parameter for the remote PTO set switch behaves in the following manner:
- The status screen for the remote PTO set switch displays "OFF" when the remote PTO set switch is released.
- The status of the remote PTO resume switch displays "OFF" when the remote PTO resume switch is released.
- The status of the remote PTO set switch changes from "OFF" to set switch "ON" when the remote PTO set switch is moved to the SET position.
- The status of the remote PTO resume switch changes from "OFF" to resume switch "ON" when the remote PTO resume switch is moved to the RESUME position.
Results:
- Yes - The set circuit and the resume circuit are functioning correctly. The inputs for the PTO are functioning properly. Continue troubleshooting if the original condition is not resolved. STOP
- No - The "PTO Configuration" is programmed to "Cab Switches". Proceed to Test Step 7.
- No - The "PTO Configuration" is programmed to "Remote Switches" or "Remote Throttle". Proceed to Test Step 8.
Test Step 6. Use Cat ET to Check the Status of the PTO On/Off Switch
 | |
| Illustration 5 | g01105784 |
Schematic of connector for breakout T (Terminal 3) Input sensor common number 2 (Terminal 56) Input number 1 (PTO on/off switch) | |
- Turn the ignition key switch to the OFF position.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Disconnect vehicle harness connector P1 from the ECM.
- Remove the wire P1-56 (input 1) from ECM connector P1.
- Install a 140-2266 Cable As (70-PIN BREAKOUT) to the ECM vehicle harness connector J1/P1.
- Verify that Cat ET is connected to the data link connector.
- Turn the ignition key switch to the ON position.
- Access the "PTO On/Off Switch" status on Cat ET.
- While the switch status is being observed on Cat ET, install the jumper into the breakout T between P1-56 (input 1) and P1-3 (input sensor common 2).
The input 1 is the PTO on/off switch.
Refer to Illustration 5.
- Turn the key switch to the OFF position.
- Reconnect all wires to the original configuration.
Expected Result:
The switch status of the "PTO On/Off Switch" on Cat ET behaves in the following manner:
- The switch status changes from "OFF" to "ON" when the jumper is in place.
- The switch status is "OFF" when the jumper is removed.
Results:
- OK - The input 1 (PTO on/off switch) of the ECM is functioning correctly. The problem is in the switches of the vehicle or the problem is in the wiring of the vehicle.
Repair: Inspect the wiring. Select one of the following options:
- Repair the wiring or replace the wiring.
- Send the vehicle to the OEM dealer for repair.
STOP
- Repair the wiring or replace the wiring.
- Not OK - The ECM is not reading the switch status change.
Repair: Perform the following diagnostic procedure:
- Temporarily connect a test ECM.
- Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.
- Recheck the system for active diagnostic codes.
- Repeat the test step.
- If the problem is resolved with the test ECM, reconnect the suspect ECM.
- If the problem returns with the suspect ECM, replace the ECM.
- Verify that the repair eliminates the problem.
STOP
Test Step 7. Use Cat ET to Check the Status of the Cruise Control Set/Resume Switch
 | |
| Illustration 6 | g01105792 |
Schematic of connector for breakout T (Terminal 5) AP sensor/switch sensor common (Terminal 35) Cruise control set (Terminal 44) Cruise control resume | |
- Turn the ignition key switch to the OFF position.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Disconnect vehicle harness connector P1 from the ECM.
- Remove the wire P1-35 (cruise control set) from the P1 ECM connector.
- Remove the wire P1-44 (cruise control resume) from the P1 ECM connector.
- Install a 140-2266 Cable As (70-PIN BREAKOUT) to the ECM vehicle harness connector J1/P1.
- Verify that Cat ET is connected to the data link connector.
- Turn the ignition key switch to the ON position, while the engine is off.
- Access the status of the cruise control set/resume switch on Cat ET.
- While the switch status is being observed on Cat ET, install the jumper into the breakout T in order to connect P1-35 (cruise control set) to P1-5 (AP sensor/switch sensor common). Also, while the switch status is being observed on Cat ET remove the jumper from the breakout T in order to disconnect P1-35 (cruise control set) from P1-5 (AP sensor/switch sensor common).
- While the switch status is being observed on Cat ET, install the jumper into the breakout T. This connects P1-44 (cruise control resume) to P1-5 (AP sensor/switch sensor common). Also, while the switch status is being observed on Cat ET, remove the jumper from the breakout T. This will disconnect P1-44 (cruise control resume) from P1-5 (AP sensor/switch sensor common).
Refer to Illustration 6.
- Turn the key switch to the OFF position.
- Reconnect all wires to the original configuration.
Expected Result:
The switch status of the cruise control set/resume switch on Cat ET behaves in the following manner:
- The switch status of the cruise control set/resume switch changes from "OFF" to set switch "ON" when the jumper is connected from P1-35 (cruise control set) to P1-5 (AP sensor/switch sensor common).
- The switch status of the cruise control set/resume switch is "OFF" when the jumper is removed.
- The switch status of the cruise control set/resume switch changes from "OFF" to resume switch "ON" when the jumper is connected from P1-44 (Cruise control resume) to P1-5 (AP sensor/switch sensor common).
Results:
- OK - The input for the set switch and the input for the resume switch of the ECM are functioning correctly. The problem is in the switches of the vehicle or the problem is in the wiring of the vehicle.
Repair: Inspect the wiring. Select one of the following options:
- Repair the wiring or replace the wiring.
- Send the vehicle to the OEM dealer for repair.
STOP
- Repair the wiring or replace the wiring.
- Not OK - The ECM is not reading the switch status change.
Repair: Perform the following diagnostic procedure:
- Temporarily connect a test ECM.
- Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.
- Recheck the system for active diagnostic codes.
- Repeat the test step.
- If the problem is resolved with the test ECM, reconnect the suspect ECM.
- If the problem returns with the suspect ECM, replace the ECM.
- Verify that the repair eliminates the problem.
STOP
Test Step 8. Use Cat ET to Check the Status of the Remote PTO Set Switch and the Remote PTO Resume Switch
 | |
| Illustration 7 | g01105788 |
Schematic of connector for breakout T (Terminal 3) Input sensor common number 2 (Terminal 58) Input number 2 (remote PTO set) (Terminal 60) Input number 3 (remote PTO resume) | |
- Turn the ignition key switch to the OFF position.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Disconnect vehicle harness connector P1 from the ECM.
- Remove the wire P1-58 (input number 2 (remote PTO set)) from ECM connector P1.
- Remove the wire P1-60 (input number 3 (remote PTO resume)) from ECM connector P1.
- Install a 140-2266 Cable As (70-PIN BREAKOUT) to the ECM vehicle harness connector J1/P1.
- Verify that CatET is connected to the data link connector.
- Turn the ignition key switch to the ON position.
- Access the "Remote PTO Set Switch" and "Remote PTO Resume Switch" status on Cat ET.
- While the status of the "Remote PTO Set Switch" is being observed on Cat ET, install the jumper into the breakout T in order to connect P1-58 (input number 2 (remote PTO set)) to P1-3 (iInput sensor common 2). Also, while the switch status is being observed on Cat ET remove the jumper from the breakout T in order to disconnect P1-58 (input number 2 (remote PTO set)) from P1-3 (input sensor common 2).
- While the status of the "Remote PTO Resume Switch" is being observed on Cat ET, install the jumper into the breakout T in order to connect P1-60 (Input number 3 (remote PTO resume)) to P1-3 (input sensor common 2). Also, while the switch status is being observed on Cat ET remove the jumper from the breakout T in order to disconnect P1-60 (input number 3 (remote PTO resume)) from P1-3 (input sensor common 2).
Refer to Illustration 7.
- Turn the key switch to the OFF position.
- Reconnect all wires to the original configuration.
Expected Result:
The switch status of the "Remote PTO Set Switch" on Cat ET behaves in the following manner:
- The switch status of the "Remote PTO Set Switch" is "OFF" when the jumper is removed.
- The switch status of the "Remote PTO Set Switch" changes from "OFF" to set switch "ON" when the jumper is connected from P1-58 (input number 2 (remote PTO set)) to P1-3 (input sensor common 2).
The switch status of the "Remote PTO Resume Switch" on Cat ET behaves in the following manner:
- The switch status of the "Remote PTO Resume Switch" is "OFF" when the jumper is removed.
- The switch status of the "Remote PTO Resume Switch" changes from "OFF" to resume switch "ON" when the jumper is connected from P1-60 (input number 3 (remote PTO resume)) to P1-3 (input sensor common 2).
Results:
- OK - Input 2 ("remote PTO set switch") and input 3 ("remote PTO resume switch") of the ECM are functioning correctly. The problem is in the switches of the vehicle or the problem is in the wiring of the vehicle.
Repair: Inspect the wiring. Select one of the following options:
- Repair the wiring or replace the wiring.
- Send the vehicle to the OEM dealer for repair.
STOP
- Repair the wiring or replace the wiring.
- No - The ECM is not reading the switch status change.
Repair: Perform the following diagnostic procedure:
- Temporarily connect a test ECM.
- Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.
- Recheck the system for active diagnostic codes.
- Repeat the test step.
- If the problem is resolved with the test ECM, reconnect the suspect ECM.
- If the problem returns with the suspect ECM, replace the ECM.
- Verify that the repair eliminates the problem.
STOP