C1.5 and C2.2 Industrial Engines Caterpillar

This procedure covers the following codes:

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	g03322761
Schematic of the IVS circuit

Illustration 2	g03322788
Typical view of the pin locations in the P1 connector for the IVS (14) Idle validation 1 (15) Idle validation 2

Test Step 1. Check the Parameters for the Idle Validation Switches

1. Use the electronic service tool to check the parameters for the IVS and low idle settings. Refer to Troubleshooting, "Customer Specified Parameters".

Results:

• OK - The parameters are set correctly. Proceed to Test Step 2.

• Not OK -

  Repair: Use the electronic service tool to set the parameters for the IVS and low idle.

  Start the engine and operate the throttle over the full operating range. Use the electronic service tool to verify that the fault has been eliminated.

  STOP

Test Step 2. 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:

   • P1:14

   • P1:15

3. Check the harness for abrasion and pinch points from the IVS 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 3.

• 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 3. Check for Active Diagnostic Codes and/or Recently Logged Diagnostic Codes

1. Connect the electronic service tool to the diagnostic 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 a poor connection in a connector.

Results:

• A 558-3 or a 2970-3 diagnostic code is active or recently logged - Proceed to Test Step 4.

• A 558-4 or a 2970-4 diagnostic code is active or recently logged - Proceed to Test Step 6.

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

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

  STOP

Test Step 4. Create a Short at the Switch Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the connector for the suspect IVS.

3. Fabricate a jumper wire that is 150 mm (6 inch) long.

4. Install the jumper wire between the two terminals on the harness connector for the suspect switch.

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

6. Turn the keyswitch to the ON position. Do not start the engine.

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

8. Observe the status of the IVS with the jumper installed.

9. Turn the keyswitch to the OFF position. Remove the jumper wire.

Results:

• The service tool indicates "In Low Idle" with the jumper installed. - The fault is in the IVS.

  Repair: Replace the suspect IVS.

  Start the engine and operate the throttle over the full operating range. Use the electronic service tool to verify that the fault has been eliminated.

  STOP

• The service tool indicates "Not In Low Idle" with the jumper installed - Proceed to Test Step 5.

Test Step 5. Check the Wiring for an Open Circuit

1. Turn the keyswitch to the OFF position.

2. Disconnect the connector for the suspect IVS.

3. Disconnect the P1 connector from the ECM.

4. Use a suitable multimeter to take the following resistance measurements:

   • The suspect switch connector to the appropriate terminal on the P1 connector.

   • The suspect switch connector to machine ground.

   Refer to Illustration 1.

Results:

• Both resistance measurements are less than 2 Ohms. -

  Repair: Perform the following procedure:

  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 Cat dealer.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a replacement ECM, install a replacement 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 replacement 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

• At least one of the resistance measurements is greater than 2 Ohms. - There is an open circuit or high resistance in the wiring for the suspect IVS.

  Repair: Replace the faulty wiring.

  Start the engine and operate the throttle over the full operating range. Use the electronic service tool to verify that the fault has been eliminated.

  STOP

Test Step 6. Create an Open Circuit at the Switch Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the connector for the suspect IVS.

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

4. Turn the keyswitch to the ON position. Do not start the engine.

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

6. Observe the status of the IVS with the connector disconnected.

7. Turn the keyswitch to the OFF position. Remove the jumper wire.

Results:

• The electronic service tool indicates "Not in Low Idle" with the connector disconnected - The fault is in the IVS.

  Repair: Replace the suspect IVS.

  Start the engine and operate the throttle over the full operating range. Use the electronic service tool to verify that the fault has been eliminated.

  STOP

• The electronic service tool indicates "In Low Idle" with the connector disconnected. - Proceed to Test Step 7.

Test Step 7. Check the Wiring for a Short Circuit

1. Turn the keyswitch to the OFF position.

2. Disconnect the harness connector for the suspect IVS.

3. Disconnect the P1 connector.

4. If the fault is on IVS 1, use a multimeter to check the resistance between P1:14 and all other terminals on the P1 connector.

5. If the fault is on IVS 2, use a multimeter to check the resistance between P1:15 and all other terminals on the P1 connector.

Expected Result:

The measured resistances are all greater than 100 Ohms.

Results:

• OK - The measured resistance in all wires is greater than 100 Ohms. The fault is in the ECM.

  Repair: Perform the following procedure:

  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 Cat dealer.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a replacement ECM, install a replacement 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 replacement 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

• Not OK - At least one of the resistance measurements is less than 100 Ohms. There is a short in the wiring for the suspect IVS.

  Repair: Replace the faulty wiring.

  Start the engine and operate the throttle over the full operating range. Use the electronic service tool to verify that the fault has been eliminated.

  STOP