C7.1 Industrial Engine and Generator Set Caterpillar

This procedure covers the following codes:

If the application is equipped with two throttles, the engine will use the second throttle until the fault is repaired.

If a second throttle is not installed or if the second throttle has a fault, the following conditions will occur:

• The engine will default to limp home mode.

• If the engine speed is higher than the speed in limp home mode, the engine will decelerate to limp home mode.

• If the engine speed is lower than the speed in limp home mode, the engine speed will remain at the current speed.

• The engine will remain at this speed while the diagnostic code remains active.

• All inputs from the faulty throttle are ignored by the ECM until the fault is repaired.

• All inputs from the repaired throttle will be ignored by the ECM until the keyswitch has been cycled.

The IVS may be installed. The IVS is required for mobile applications. The IVS is part of the throttle position sensor. The IVS is CLOSED when the low idle is set.

The configuration parameters for the throttle and for the IVS thresholds are programmed into the ECM. Use the electronic service tool in order to display the configuration parameters for the throttle and for the IVS.

If the IVS operates outside of the programmed range, then the engine speed may not respond to changes in the throttle position.

The electronic service tool may be used for the following:

• If necessary, reset the IVS threshold for an existing IVS.

• If necessary, view the IVS change point and reset the IVS thresholds when a new throttle assembly is installed.

Illustration 1	g02140710
Schematic of the IVS circuit

Illustration 2	g01981113
Typical view of the pin locations in the P1 connector for the IVS (18) Sensor Ground (22) Idle validation 1 (40) Idle validation 2

Test Step 1. Check for Active Diagnostic Codes and/or Recently Logged Diagnostic Codes

1. Connect the electronic service tool to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

   Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection between a socket and a pin in a connector or of a poor connection between a wire and a terminal.

Results:

• A 558-2 or a 2970-2 diagnostic code is active or recently logged at this time. - Proceed to Test Step 2.

• No diagnostic codes are active - The problem may have been intermittent.

  Repair: Carefully inspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

Test Step 2. Check the Operation of the IVS

1. Connect the electronic service tool to the diagnostic connector.

2. Turn the keyswitch to the ON position.

3. Use the electronic service tool in order to check the current "Throttle Configuration".

4. Select the "SERVICE" option from the drop-down menu of the electronic service tool.

5. Select the "Throttle Configuration" option on the electronic service tool. Select the appropriate "Throttle Configuration" summary from the menu on the left of the screen. The IVS window for the throttle will indicate "YES" if an IVS is installed.

6. Select the "Throttle status" function on the electronic service tool. Select "Status" function and then select "Throttles" function.

7. The throttle is set in the low idle position.

8. Operate the throttle slowly. The IVS status should change from CLOSED (ON) to OPEN (OFF).

Results:

• The IVS state changes from CLOSED (ON) to OPEN (OFF) - Proceed to Test Step 3.

• The IVS does not operate - Proceed to Test Step 4.

Test Step 3. Check the IVS Threshold

1. Connect the electronic service tool to the diagnostic connector.

2. Turn the keyswitch to the ON position.

3. Use the electronic service tool in order to check the current "Throttle Configuration".

4. Select the "SERVICE" option from the drop-down menu of the electronic service tool.

5. Select the "Throttle Configuration" option on the electronic service tool. Select the appropriate "Throttle Configuration" summary from the menu on the left of the screen. The IVS window for the throttle will indicate "YES" if an IVS is installed. Make a note of the "Idle Validation Min OFF Threshold" parameters that are displayed in the "Throttle Configuration" menu of the electronic service tool. Make a note of the "Idle Validation Max ON Threshold" parameters that are displayed in the "Throttle Configuration" menu of the electronic service tool.

6. To select the "Throttle status" function on the electronic service tool, select "Status" function and then select "Throttles" function.

7. The throttle is set in the low idle position.

8. Operate the throttle slowly. The IVS status should change from CLOSED (ON) to OPEN (OFF).

Results:

• The IVS switch operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. - STOP

• The IVS switch cannot operate within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters - Proceed to Test Step 8.

Test Step 4. Inspect Electrical Connectors and the Harness

1. Inspect the P1/J1 connectors, the harness and all of the connectors for the IVS. 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 suspect idle validation switch:

   • P1:18

   • P1:22

   • P1:40

3. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in).

4. Check the harness for abrasion and pinch points from the throttle switch to the ECM.

Expected Result:

All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, abrasion, and pinch points.

Results:

• No harness or connector problems found - Proceed to Test Step 5.

• Problems found with harness or connectors. -

  Repair: Perform the following repair:

  Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.

  Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 5. Check the Location of the Fault

1. Disconnect the IVS harness connector.

2. Install a jumper wire between the IVS connections on the harness.

3. Turn the keyswitch to the ON position.

4. Install a jumper wire between the IVS connections on the harness. Use the electronic service tool in order to check for diagnostic codes.

5. Remove the jumper wire that is between the IVS connections on the harness. Use the electronic service tool in order to check for diagnostic codes.

Expected Result:

Connect the jumper wire. The IVS state on the electronic service tool will display the ON position.

Disconnect the jumper wire. The IVS state on the electronic service tool will display the OFF position.

Results:

• With the jumper wire connected, the electronic service tool displays the IVS state in the ON position on the throttle status screen. With the jumper wire disconnected, the electronic service tool displays the IVS state in the OFF position on the throttle status screen. - The IVS is suspect. Proceed to Test Step 7.

• The IVS status that is displayed on the electronic service tool does not change with the jumper wire either removed or installed. - The harness and/or the ECM are suspect. Proceed to Test Step 6.

Test Step 6. Check the ECM Function

1. Disconnect the P1 connector.

2. If the IVS 1 is suspect, temporarily remove P1:22. If the IVS 2 is suspect, temporarily remove connector P1:40.

3. Fabricate a jumper wire.

4. Turn the keyswitch to the ON position.

5. Install the jumper wire between the removed connector pin on the P1 connector and P1:18.

6. Use the electronic service tool in order to monitor the IVS status. Note the status of the IVS.

7. Disconnect the jumper wire.

8. Use the electronic service tool in order to monitor the IVS status. Note the status of the IVS.

Expected Result:

When the jumper wire is installed, the IVS state on the electronic service tool throttle status screen will display the ON position.

When the jumper wire is disconnected, the IVS state on the electronic service tool throttle status screen will display the OFF position.

Results:

• When the jumper wire is connected, the electronic service tool shows the IVS state in the ON position. When the jumper wire is disconnected, the electronic service tool shows the IVS state in the OFF position. -

  Repair:

  1. Inspect the harness between the ECM and IVS.

  2. Locate the fault.

  3. Repair the harness and/or replace the harness.

  4. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault.

  STOP

• The IVS status that is displayed on the electronic service tool does not change with the jumper wire either removed or installed. - The ECM is suspect.

  Repair: Perform the following repair:

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Contact the Technical Communicator at a Caterpillar dealer.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  4. Use the electronic service tool to recheck the system for active diagnostic codes.

  5. If the fault is eliminated with the test ECM, reconnect the suspect ECM.

  6. If the fault returns with the suspect ECM, replace the ECM.

  7. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 7. Check the IVS at the Sensor

1. Turn the keyswitch to the OFF position.

2. Disconnect the IVS.

3. Set the throttle to low idle.

4. Check the resistance of the IVS.

5. Set the throttle to high idle.

6. Check the resistance of the IVS.

Expected Result:

The IVS reading should be less than 10 Ohms at low idle.

The IVS reading should be more than 20000 Ohms at high idle.

Results:

• The IVS indicates the resistance that is shown in the test - No fault is indicated at this time. Recheck the harness for intermittent connections.

  STOP

• The IVS is not functioning correctly. -

  Repair: Replace the IVS or replace the throttle sensor. Refer to OEM documentation for information on the throttle sensor. Check the IVS calibration.

  Proceed to Test Step 8.

Test Step 8. Check the IVS Calibration

1. Connect the electronic service tool to the diagnostic connector.

2. Turn the keyswitch to the ON position.

3. Select the "Throttle Configuration" option on the electronic service tool. Select the appropriate "Throttle Configuration" summary from the menu on the left of the screen. The IVS window for the throttle will indicate "YES" if an IVS is installed. Make a note of the "Idle Validation Min OFF Threshold" parameters that are displayed in the "Throttle Configuration" menu of the electronic service tool. Make a note of the "Idle Validation Max ON Threshold" parameters that are displayed in the "Throttle Configuration" menu of the electronic service tool.

4. Select the "Throttle status" function on the electronic service tool. Select "Status" function and then select "Throttles" function.

5. Set the throttle to low idle.

6. Operate the throttle slowly toward high idle. The raw percentage values for the throttle that are shown on the electronic service tool should increase and the IVS status should change from CLOSED (ON) to OPEN (OFF) position. Make a note of the raw reading for the throttle when the IVS reading changes from the CLOSED position to the OPEN position. Repeat this step in order to obtain accurate raw percentage values for the throttle. The noted value should be within the previously noted "Idle Validation Min OFF Threshold" and "Idle Validation Max ON Threshold" limits.

7. The throttle is set to the full throttle position or the high idle position.

8. Operate the throttle slowly toward low idle. The raw percentage values for the throttle that are shown on the electronic service tool should decrease and the IVS status should change from OPEN (OFF) to CLOSED (ON) position. Make a note of the raw reading for the throttle when the IVS reading changes from the OPEN position to the CLOSED position. Repeat this step in order to obtain accurate raw percentage values for the throttle. The noted value should be within the previously noted "Idle Validation Min OFF Threshold" and "Idle Validation Max ON Threshold" limits.

Expected Result:

The IVS operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" values that are shown on the "Configuration" menu of the electronic service tool.

Results:

• The IVS operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" values that are shown on the "Configuration" menu of the electronic service tool. - STOP

• The IVS does not operate within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" values that are shown on the "Configuration" menu of the electronic service tool. - Proceed to Test Step 9.

Test Step 9. Use the Electronic Service Tool to Reset the IVS Threshold Limits

The electronic service tool can be used to change the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" in order to suit the type of throttle that is installed. The limits are shown in the "Throttle Configuration" screen which is located in the "Service" menu.

1. Refer to Test Step 8 and record the raw value of the throttle signal when the idle validation switch changes from the CLOSED position to the OPEN position.

   Note: The default value for the "Idle Validation Min OFF Threshold" is 21%. The lowest value that should be set is 5%. The default value for the "Idle Validation Max ON Threshold" is 25%. The maximum value that is expected is 28%.

2. Set the "Idle Validation Min OFF Threshold" to 3% below the raw value that was previously recorded.

3. Set the "Idle Validation Max ON Threshold" to 3% above the raw value.

4. Enter the new threshold limits into the electronic service tool. Click "Submit" on the electronic service tool screen.

5. Turn the keyswitch to the OFF position and wait at least 5 seconds. Turn the keyswitch to the ON position.

6. Repeat Test Step 8. Check that the IVS operates within the newly set threshold limits.

Results:

• The fault is cleared after programming the new calculated values. - STOP

• The fault is not cleared. -

  Repair: Contact the Technical Communicator at a Caterpillar dealer.

  STOP