C7.1 Engines and Generator Sets Caterpillar

Idle Validation - Test

Usage:

C7.1 770

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Trouble Codes for the Idle Validation Switches
J1939 Code	CDL Code	Code Description	Comments
558-2	1634-2	Accelerator Pedal 1 Low Idle Switch : Erratic, Intermittent, or Incorrect	The Electronic Control Module (ECM) detects the following condition: The signal from the Idle Validation Switch (IVS) is invalid. If equipped, the warning light will come on. The ECM will log the diagnostic code.
2970-2	1635-2	Accelerator Pedal 2 Low Idle Switch : Erratic, Intermittent, or Incorrect
Follow the troubleshooting procedure to identify the root cause of the fault.

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 with an analog throttle installed. 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 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.

During the following procedure, refer to the electrical schematic for the application.

Complete the procedure in the order in which the steps are listed.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Active Diagnostic Codes and/or Recently Logged Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. C. 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.	Diagnostic codes	Result: No diagnostic codes are active - the problem may have been intermittent. Repair: Carefully inspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect". Result: A 558-2 (1634-2) or 2970-2 (1635-2) diagnostic code is active or recently logged. Proceed to Test Step 2.
2. Check the Operation of the IVS A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. Note: Do not start the engine. C. Use the electronic service tool to check the current "Throttle Configuration". D. Select the "SERVICE" option from the drop-down menu of the electronic service tool. E. 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. F. Select the "Throttle status" function on the electronic service tool. Select "Status" function and then select "Throttles" function. G. The throttle is set in the low idle position. H. Operate the throttle slowly. The IVS status should change from CLOSED (ON) to OPEN (OFF).	IVS status change	Result: The IVS state changes from CLOSED (ON) to OPEN (OFF) Proceed to Test Step 3. Result: The IVS state does not change. Proceed to Test Step 4.
3. Check the IVS Threshold A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. C. Use the electronic service tool to check the current "Throttle Configuration". D. Select the "SERVICE" option from the drop-down menu of the electronic service tool. E. 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. F. To select the "Throttle status" function on the electronic service tool, select "Status" function and then select "Throttles" function. G. The throttle is set in the low idle position. H. Operate the throttle slowly. The IVS status should change from CLOSED (ON) to OPEN (OFF).	IVS operates within threshold.	Result: The IVS switch operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. The IVS is operating correctly. Return the engine to service. Result: 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.
4. Inspect Electrical Connectors and the Harness A. Inspect the P1/J1 connectors, the harness and all the connectors for the IVS. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. B. 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. C. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). D. Check the harness for abrasion and pinch points from the throttle switch to the ECM.	Loose connection or damaged wire	Result: Faults found in harness or connectors. Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all the seals are correctly in place and ensure that the connectors are correctly connected. Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: No harness or connector faults found. Proceed to Test Step 5.
5. Check the Location of the Fault A. Disconnect the IVS harness connector. B. Fabricate a jumper wire. C. Turn the keyswitch to the ON position. D. Install a jumper wire between the IVS connections on the harness. Use the electronic service tool to check for diagnostic codes. E. Remove the jumper wire that is between the IVS connections on the harness. Use the electronic service tool to check for diagnostic codes.	IVS state on with jumper installed. IVS state off with jumper removed.	Result: 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. Proceed to Test Step 8. Result: The IVS status that is displayed on the electronic service tool does not change with the jumper wire either removed or installed. Proceed to Test Step 6.
6. Check the Wiring for an Open Circuit A. Disconnect the IVS harness connector. B. Disconnect the P1 connector. C. If the fault is on IVS1, check the resistance between the IVS1 input terminal on the IVS harness connector and the "Idle Validation (IVS) 1" terminal on the P1 connector. D. If the fault is on IVS2, check the resistance between the IVS2 input terminal on the IVS harness connector and the "Idle Validation (IVS) 2" terminal on the P1 connector. E. Check the resistance between the IVS1 output terminal on the applicable IVS harness connector and the "Idle Validation Ground" terminal on the P1 connector.	Less than 2.0 Ohms	Result: One or more of the measured resistances is greater than 2.0 Ohms. There is an open circuit in the wiring. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The measured resistance in all wires is less than 2.0 Ohms. Proceed to Test Step 7.
7.Check the Wiring for a Short Circuit A. Disconnect the P1 connector. B. Disconnect both IVS harness connectors. C. Check the resistance between the "Idle Validation (IVS) 1" terminal on the P1 connector and all other terminals on the P1 connector. D. Check the resistance between the "Idle Validation (IVS) 2" terminal on the P1 connector and all other terminals on the P1 connector. E. Check the resistance between the "Idle Validation Ground" terminal on the P1 connector and all other terminals on the P1 connector.	Greater than 100 Ohms	Result: One or more of the measured resistances is less than 100 Ohms. There is a short circuit in the wiring. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are greater than 100 Ohms. Contact the Dealer Solutions Network (DSN).
8. Check the IVS Calibration A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. C. 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. Make a note of the "Idle Validation Max ON Threshold" parameters. D. Select the "Throttle status" function on the electronic service tool. Select "Status" function and then select "Throttles" function. E. Set the throttle to low idle. F. Operate the throttle slowly toward high idle. The raw percentage values for the throttle 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 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. G. Set the throttle to the full throttle position or the high idle position. H. Operate the throttle slowly toward low idle. The raw percentage values for the throttle 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 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.	The IVS operates within the thresholds.	Result: The IVS operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" values. The IVS is operating correctly. Return the engine to service. Result: The IVS does not operate within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" values. Proceed to Test Step 9.
9. Use the Electronic Service Tool to Reset the IVS Threshold Limits Note: The electronic service tool can be used to change the following parameters to suit the type of throttle that is installed: · Idle Validation Min OFF Threshold · Idle Validation Max ON Threshold Note: The limits are shown in the "Throttle Configuration" screen which is located in the "Service" menu. A. Refer to Test Step 8. “Check the IVS Calibration”. 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%. B. Set the "Idle Validation Min OFF Threshold" to 3% below the raw value that was previously recorded. C. Set the "Idle Validation Max ON Threshold" to 3% above the raw value. D. Enter the new threshold limits into the electronic service tool. Click "Submit" on the electronic service tool screen. E. Turn the keyswitch to the OFF position and wait at least 5 seconds. Turn the keyswitch to the ON position. F. Repeat Test Step 8. Check that the IVS operates within the newly set threshold limits.	The fault is cleared.	Result: The fault is cleared after programming the new calculated values. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Return the engine to service. Result: The fault is not cleared. Contact the Dealer Solutions Network (DSN).