C4.4 and C6.6 Industrial Engines and Engines for Caterpillar Built Machines Caterpillar

Use this procedure if any of the following diagnostic codes are active:

• 0091-02 Throttle Position Sensor erratic, intermittent, or incorrect

• 0774-02 Secondary Throttle Position Sensor erratic, intermittent, or incorrect

The Idle Validation Switch (IVS) may be installed. The IVS is required for mobile applications that use an analog throttle. The IVS is part of the analog throttle demand sensor. The IVS is CLOSED when the low idle is set.

The demand settings for the analog throttle that are valid for the IVS threshold are programmed into the Electronic Control Module (ECM). Use the electronic service tool in order to display the demand settings for the analog throttle.

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	g01803633
Schematic of the idle validation switch (IVS) circuit

Illustration 2	g01803694
Typical view of the pin locations in the P1 connector for the idle validation switch (35) Sensor Ground (GND) (44) Idle validation (IVS) 2 (45) Idle validation (IVS) 1

Test Step 1. Check the Operation of the Idle Validation Switch (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 analog "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. 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).

Expected Result:

The IVS state changes from CLOSED (ON) to OPEN (OFF).

Results:

• OK - The IVS state changes from CLOSED (ON) to OPEN (OFF). Proceed to Test Step 2.

• Not OK - The IVS does not operate.

  Repair:

  Proceed to Test Step 3.

Test Step 2. Check the Idle Validation Switch (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 analog "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).

Expected Result:

The IVS switch operates between the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. Use the electronic service tool in order to view the parameters of the IVS switch.

Results:

• OK - The IVS switch operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. Use the electronic service tool in order to view the parameters of the IVS switch.STOP

• Not OK - The IVS switch cannot operate within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. Use the electronic service tool in order to view the parameters of the IVS switch.

  Repair:

  Proceed to Test Step 7.

Test Step 3. 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:
   • P1:35

   • P1:44

   • P1:45

3. Check the screw for the ECM connector for the correct torque of 5.0 N·m (44 lb in).

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

Expected Result:

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

Results:

• OK - Proceed to Test Step 4.

• Not OK -

  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 completely coupled.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 4. 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 throttle status screen will display the ON position.

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

Results:

• OK - The jumper wire is connected. The electronic service tool displays the IVS state in the ON position. The jumper wire is disconnected. The electronic service tool displays the IVS state in the OFF position. The IVS is suspect. Proceed to Test Step 6.

• Not OK - The harness and/or the ECM are suspect. Proceed to Test Step 5.

Test Step 5. Check the ECM function

1. Disconnect the P1 connector.

2. If the IVS 2 is suspect, temporarily remove connector P1:45. If the IVS 1 is suspect, temporarily remove P1:44.

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 P1:35.

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:

• OK - 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

• Not OK - 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.

     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 6. Check the Idle Validation Switch (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 more than 20000 Ohms.

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

Results:

• OK - 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

• Not OK - 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.

  Refer to Test Step 7.

• Verify that the repair has eliminated the fault. Clear the logged diagnostic codes. - STOP

Test Step 7. Check the Idle Validation Switch (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 analog "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:

• OK - 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

• Not OK - Proceed to Test Step 8.

Test Step 8. Use the Electronic Service Tool to Reset the Idle Validation Switch (IVS) Threshold Limits

The electronic service tool can be used to reset the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" limits that are shown in the current throttle configuration summary.

1. Calculate the new "Idle Validation Min OFF Threshold" limit. The "Idle Validation Min OFF Threshold" limit is 3% below the lowest raw values that are noted in Test Step 7.

   Note: The default value for the "Idle Validation Min OFF Threshold" is 10%. The lowest value that should be set is 5%.

2. Calculate the new "Idle Validation Max ON Threshold" limit. The "Idle Validation Max ON Threshold" is 3% above the raw values that was noted for the "Idle Validation Max ON Threshold" limit. The "Idle Validation Max ON Threshold" is 3% above the highest raw % value that was noted in Test Step 7.

   Note: The default value for the "Idle Validation Max ON Threshold" is 25%. The maximum value that is expected is 28%.

3. Enter the new threshold limits into the electronic service tool.

4. Turn the keyswitch to the OFF position. Turn the keyswitch to the ON position.

5. Repeat Test Step 7. Check that the IVS operates within the newly set threshold limits.

Expected Result:

The fault is cleared.

Results:

• OK - STOP

• Not OK -

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

  STOP