3126E Engine for Combat and Tactical Vehicles Caterpillar

Use this procedure under the following situation:

Use this procedure to determine that the vehicle wiring and the ECM are functioning properly for the features of Dedicated PTO.

The following background information is related to this procedure:

INPUT #1

The input 1 is used for the circuit for the PTO on/off switch when the PTO Configuration is programmed to "Cab Switches", "Remote Switches", or "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 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 ET. The status parameter indicates the cause of the kickout. This must be performed before the ignition key switch 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, "No Occurrence" or "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.

The following kickout status parameter is available:

• PTO kickout

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

The input 2 is used for the PTO set/rpm increase switch when the "PTO Configuration" is programmed to "Remote Switches" or "Remote Throttle".

INPUT 3

The input 3 is used for the PTO resume/rpm decrease switch when the "PTO Configuration" is programmed to "Remote Switches" or "Remote Throttle".

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 cab accelerator pedal position sensor 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 Set To Remote Switches or Remote Throttle.

When the "PTO Configuration" is programmed to "Remote Switches" or "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

• Cab accelerator pedal position sensor

• Cab cruise control set/resume switch

A remote accelerator pedal position sensor is connected to the 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:

• The "Input Sensor Common 1" is terminal 18.

• The "Input Sensor Common 2" is terminal 3.

• The "AP Sensor/Switch Sensor Common" is terminal 5.

Illustration 1	g00644420
This illustration is for the schematic for "cab switches" for "PTO configuration".

Illustration 2	g00644427
This illustration is for the schematic for "remote switches" for "PTO configuration".

Illustration 3	g00644448
This illustration is for the schematic for "remote throttle" for "PTO configuration".

Test Step 1. Check the Programming of the Dedicated PTO Customer Parameter.

1. Connect ET to the cab data link connector.

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

3. Access the Dedicated PTO Customer Parameters on ET. Note the programming of the PTO Configuration Parameter.

Expected Result:

The "PTO Configuration" is programmed to "Cab Switches", "Remote Switches", or "Remote Throttle".

Results:

• Yes - Proceed to Test Step 2.

• No - The Dedicated PTO features are not programmed for this engine. If PTO operation is desired, the "PTO Configuration" must be programmed to "Cab Switches", "Remote Switches", or "Remote Throttle". Stop.

Test Step 2. Determine the PTO Installation Setup.

1. From the programming of the PTO Configuration Parameter, review the truck wiring in order to determine the method of installation of the wiring. Talk to the driver about the use of the PTO.

2. 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 PTO Interlocks that are used in the installation.

3. Contact the installer of the PTO component, if necessary.

4. 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.

5. Record the "PTO Configuration".

Expected Result:

The requirements for the installation and the application have been reviewed.

Results:

• OK - Proceed to Test Step 3.

Test Step 3. Inspect Electrical Connectors and Wiring.

Illustration 4	g00713728
Terminal locations for ECM

1. Thoroughly inspect ECM connector J1/P1, the firewall bulkhead connectors, and any connectors that are used by the PTO.

   Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. 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. The following connections should be tested if the connections are used:
   • terminal 3

   • terminal 5

   • terminal 30

   • terminal 35

   • terminal 44

   • terminal 56

   • terminal 58

   • terminal 60

   • terminal 68

   Refer to Illustration 4.

3. Check the ECM connector (allen head screw) for the proper torque of 6.0 n·m (55 lb in).

4. Check the harness and wiring for abrasion and pinch points from the 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 4.

• 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 4. Check the PTO On/Off Switch Circuit with ET.

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

2. For the input 1 (PTO on/off switch), access the ET status screens that display the following status parameters:
   • "PTO Config"

   • "PTO ON/OFF Switch"

3. Verify that each of the PTO interlocks are set. Then, while the ET status screen is being monitored turn on the PTO on/off switch and turn off the PTO on/off switch.

   An example of a PTO interlock would be a parking brake that is intended to allow PTO engine control under specific conditions.

Expected Result:

Result 1 The status of the PTO on/off switch on 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 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 ET does not change from "OFF" to "ON" when the PTO on/off switch is turned to the OFF position and the ON position.

Results:

• Result 1 - Proceed to Test Step 5.

• Result 2 -

  Repair: Perform the following diagnostic procedure: Troubleshooting, "Remote PTO Accelerator Position Sensor Circuit - Test"

  Stop.

• Result 3 - Proceed to Test Step 6.

Test Step 5. Check Status of the Set/Resume Input on ET.

Note: The set/resume input increases the engine rpm and the set/resume input decreases the engine rpm.

1. Find the PTO set/resume 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 "Remote Throttle", a dedicated PTO set/resume 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 ET. The parameter is located on the same status screen as the cruise/idle switch.

2. While the ET status screen for the switch is being monitored, 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 Remote Throttle.

   View the status parameter on ET for the "Remote PTO Set Switch" and the "Remote PTO Resume Switch".

3. While the ET status screen 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.

Expected Result:

When the "PTO Configuration" is programmed to "Cab Switches", the status parameter for the cruise control set/resume switch on 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 set switch "ON" when the switch is moved to the SET position.

• The status of the cruise control set/resume switch changes from set switch "ON" to resume switch "ON" when the resume switch is moved to the RESUME position.

When the "PTO Configuration" is programmed to "Remote Switches" or "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 PTO Inputs are functioning properly. Continue troubleshooting if the original condition is not resolved. Stop.

• No (programmed to "Cab Switches") - The "PTO Configuration" is programmed to "Cab Switches". Proceed to Test Step 7.

• No (programmed to "Remote Switches" or "Remote Throttle") - The "PTO Configuration" is programmed to "Remote Switches" or "Remote Throttle". Proceed to Test Step 8.

Test Step 6. Check the Status of the PTO On/Off Switch on ET.

Illustration 5	g00768799
ECM breakout T-connector

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

2. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

3. Disconnect vehicle harness connector P1 from the ECM.

4. Connect a breakout T to ECM connector J1 and connect P1 to the breakout T.

5. Connect ET to the cab data link connector.

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

7. Access the "PTO On/Off Switch" status on ET.

8. While the switch status is being observed on ET install the jumper into the breakout T in order to connect terminal 56 (input 1) to terminal 3 (input sensor common #2).

   The input 1 is the PTO on/off switch.

   Refer to Illustration 5.

Expected Result:

The switch status of the "PTO On/Off Switch" on ET behaves in the following manner:

• The switch status is "OFF" when the jumper is removed.

• The switch status changes from "OFF" to "ON" when the jumper is in place.

Results:

• Yes - 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.

  Verify that the repair eliminates the problem.

  Stop.

• No - The ECM is not reading the switch status change.

  Repair: Perform the following diagnostic procedure:

  1. Temporarily connect a test ECM.

  2. Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.

  3. Remove all jumpers and replace all connectors.

  4. Recheck the system for active diagnostic codes.

  5. Repeat the test step.

  6. If the problem is resolved with the test ECM, reconnect the suspect ECM.

  7. If the problem returns with the suspect ECM, replace the ECM.

  8. Verify that the repair eliminates the problem.

  Stop.

Test Step 7. Check the Status of the Cruise Control Set/Resume Switch on ET.

Illustration 6	g00768798
ECM breakout T-connector

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

2. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

3. Disconnect vehicle harness connector P1 from the ECM.

4. Connect a breakout T to ECM connector J1 and connect P1 to the breakout T.

5. Connect ET to the cab data link connector.

6. Turn the ignition key switch to the ON position, while the engine is off.

7. Access the status of the cruise control set/resume switch on ET.

8. While the switch status is being observed on ET install the jumper into the breakout T in order to connect terminal 35 (Set) to terminal 5 (AP sensor/switch sensor common). Also, while the switch status is being observed on ET remove the jumper from the breakout T in order to disconnect terminal 35 (Set) from terminal 5 (AP sensor/switch sensor common).

9. While the switch status is being observed on ET, install the jumper into the breakout T. This connects terminal 44 (resume) to terminal 5 (AP sensor/switch sensor common). Also, while the switch status is being observed on ET, remove the jumper from the breakout T. This will disconnect terminal 44 (resume) from terminal 5 (AP sensor/switch sensor common).

   Refer to Illustration 6.

Expected Result:

The switch status of the cruise control set/resume switch on ET behaves in the following manner:

• 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 set switch "ON" when the jumper is connected from terminal 35 (Set) to terminal 5 (AP sensor/switch sensor common).

• The switch status of the cruise control set/resume switch changes from "OFF" to resume switch "ON" when the jumper is connected from terminal 44 (switch resume terminal) to terminal 5 (AP sensor/switch sensor common).

Results:

• Yes - The set input and the resume input 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.

  Verify that the repair eliminates the problem.

  Stop.

• No - The ECM is not reading the switch status change.

  Repair: Perform the following diagnostic procedure:

  1. Temporarily connect a test ECM.

  2. Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.

  3. Remove all jumpers and replace all connectors.

  4. Recheck the system for active diagnostic codes.

  5. Repeat the test step.

  6. If the problem is resolved with the test ECM, reconnect the suspect ECM.

  7. If the problem returns with the suspect ECM, replace the ECM.

  8. Verify that the repair eliminates the problem.

  Stop.

Test Step 8. Check the Status of the Remote PTO Set Switch and the Remote PTO Resume Switch on ET.

Illustration 7	g00768769
ECM Breakout T-connector

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

2. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

3. Disconnect vehicle harness connector P1 from the ECM.

4. Connect a breakout T to ECM connector J1 and connect P1 to the breakout T.

5. Connect ET to the cab data link connector.

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

7. Access the Remote PTO Set Switch and Remote PTO Resume Switch status on ET.

8. While the status of the Remote PTO Set Switch is being observed on ET, install the jumper into the breakout T in order to connect terminal 58 (input 2) to terminal 3 (input sensor common #2). Also, while the switch status is being observed on ET remove the jumper from the breakout T in order to disconnect terminal 58 (input 2) from terminal 3 (input sensor common #2).

9. While the status of the Remote PTO Resume Switch is being observed on ET, install the jumper into the breakout T in order to connect terminal 60 (input 3) to terminal 3 (input sensor common #2). Also, while the switch status is being observed on ET remove the jumper from the breakout T in order to disconnect terminal 60 (input 3) from terminal 3 (input sensor common #2).

   The input 2 is the set switch for the PTO and the input 3 is the resume switch for the PTO.

   Refer to Illustration 7.

Expected Result:

The switch status of the Remote PTO Set Switch on 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 terminal 58 (input 2) to terminal 3 (input sensor common #2).

The switch status of the Remote PTO Resume Switch on 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 terminal 60 (input 3) to terminal 3 (input sensor common #2).

Results:

• Yes - The input 2 (Remote PTO Set Switch) and the 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.

  Verify that the repair eliminates the problem.

  Stop.

• No - The ECM is not reading the switch status change.

  Repair: Perform the following diagnostic procedure:

  1. Temporarily connect a test ECM.

  2. Ensure that the "PTO Configuration" of the test ECM matches the "PTO Configuration" of the suspect ECM.

  3. Remove all jumpers and replace all connectors.

  4. Recheck the system for Active diagnostic codes.

  5. Repeat the test step.

  6. If the problem is resolved with the test ECM, reconnect the suspect ECM.

  7. If the problem returns with the suspect ECM, replace the ECM.

  8. Verify that the repair eliminates the problem.

  Stop.