C3.4B Engines Caterpillar

Idle Validation - Test

Usage:

CCS7 4B2

This procedure covers the following diagnostic codes.

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Table 1
Diagnostic Trouble Codes
J1939 Code	Code Description	Comments
558-2	Accelerator Pedal 1 Low Idle Switch : Erratic, Intermittent, or Incorrect	The Electronic Control Module (ECM) detects one of the following conditions: The signal voltage from the throttle pedal is less than 1.05 V for 0.3 seconds while the idle validation switch is not active. The signal voltage from the throttle pedal is greater than 1.25 V for 0.3 seconds while the idle validation switch is active. The warning lamp will flash. The engine will be derated.
2970-2	Accelerator Pedal 2 Low Idle Switch : Erratic, Intermittent, or Incorrect
Follow the troubleshooting procedure in order to identify the root cause of the problem.

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.

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Illustration 1	g03726319
Schematic diagram for the Idle Validation Switch (IVS) switch circuit Not all connectors are shown. Refer to the Electrical Schematic for the application.

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Illustration 2	g03726324
View of the pin locations on the P1 connector for the IVS circuit (42) IVS 2 (67) IVS 1

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Active Diagnostic Codes A. Establish communication between the electronic service tool and the ECM. Refer to Troubleshooting, "Electronic Service Tools" B. Check for active or logged codes.	Diagnostic Trouble Codes	Result: There is an active or logged , 558-2 or 2970-2 diagnostic code. Proceed to Test Step 2.
2. Check the Operation of the IVS A. Turn the keyswitch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the keyswitch to the ON position. D. Use the electronic service tool in order to check the current "Throttle Configuration". E. Select the "SERVICE" option from the drop-down menu of the electronic service tool. F. 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. G. Select the "Throttle status" function on the electronic service tool. Select "Status" function and then select "Throttles" function. H. The throttle is set in the low idle position. I. Operate the throttle slowly. The IVS status should change from CLOSED (ON) to OPEN (OFF).	Switch state	Result: The IVS state changes from CLOSED (ON) to OPEN (OFF). Proceed to Test Step 3. Result: The IVS does not operate 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 in order 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).	Switch operation	Result: The IVS switch operates within the "Idle Validation Min OFF Threshold" and the "Idle Validation Max ON Threshold" parameters. The fault appears to be resolved. 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 10.
4. Inspect Electrical Connectors and Wiring A. Inspect the P1/J1 ECM connector. B. Inspect the connectors for the throttle position sensors. C. Perform a 30 N (6.7 lb) pull test on each of the wires in the ECM connector and the connector for the throttle position sensors. D. Check all of the wiring associated with the throttle position sensors for abrasions and pinch points.	Damaged wire or connector	Result: A damaged wire or damaged connector was not found. Proceed to Test Step 5. Result: A damaged wire or damaged connector was found. Repair: Repair the damaged wire or the damaged connector. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
5. Check the Voltage at the IVS Switch A. Disconnect the IVS harness connector. B. Turn the keyswitch to the ON position. C. Use a suitable multimeter to measure the voltage between the IVS terminal on the harness connector and a suitable ground. D. Turn the keyswitch to the OFF position.	7.9 V to 12.2 V	Result: The voltage is within the expected range. Proceed to Test Step 6. Result: The voltage is not within the expected range. Proceed to Test Step 7.
6. Check that the IVS is Grounded A. Disconnect the IVS harness connector. B. Turn the keyswitch to the ON position. C. Use a suitable multimeter to measure the voltage between the IVS terminal on the harness connector the ground terminal on the harness connector. D. Turn the keyswitch to the OFF position.	7.9 V to 12.2 V	Result: The voltage is within the expected range. Proceed to Test Step 9. Result: The voltage is not within the expected range. The fault is in the ground wire for the suspect IVS. Repair: Replace the faulty wiring. Refer to the OEM for more information on the wiring for the IVS. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
7. Check the Application Harness for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect IVS. Disconnect the P1 connector. C. If the IVS 1 is suspect, use a suitable multimeter to measure the resistance between the IVS terminal on the harness connector to P1:76. If the IVS 2 is suspect, use a suitable multimeter to measure the resistance between the IVS terminal on the harness connector to P1:42.	Less than 5 Ohms	Result: The measured resistance is less than 5 Ohms. Proceed to Test Step 8. Result: The measured resistance is greater than 5 Ohms. There is an open circuit or high resistance in the wiring between the IVS and the ECM. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
8. Check the Application Harness for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the suspect IVS connector. Disconnect the P1 connector. C. If the IVS 1 is suspect, use a suitable multimeter to measure the resistance between P1:76 and all other terminals on the P1 connector. If the IVS 2 is suspect, use a suitable multimeter to measure the resistance between P1:42 and all other terminals on the P1 connector.	Greater than 1 k Ohm	Result: All resistance measurements are greater than 1 k Ohm. Contact the Dealer Solution Network (DSN). Result: At least one of the measured resistances is less than 1 k Ohm. There is a short in the wiring between the connector for the suspect IVS and the P1 connector. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
9. Check the IVS at the Sensor A. Turn the keyswitch to the OFF position. B. Disconnect the IVS. C. Set the throttle to low idle. D. Check the resistance of the IVS. E. Set the throttle to high idle. F. Check the resistance of the IVS.	Less than 10 Ohms at low idle. Greater than 2000 Ohms at high idle.	Result: The IVS indicates the expected resistance. Repair: No fault is indicated at this time. Recheck the harness for intermittent connections. Result: At least one of the resistance measurements is outside of the expected range. Repair: Replace the IVS or replace the throttle sensor. Refer to OEM documentation for information on the throttle sensor. Proceed to Test Step 10.
10. 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 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. 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 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. G. The throttle is set 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 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.	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.	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. 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 that are shown on the "Configuration" menu of the electronic service tool. Proceed to Test Step 11.
11. 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. A. 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%. 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.	Fault cleared	Result: The fault is cleared after programming the new calculated values. Return the engine to service. Result: The fault is not cleared. Contact the Dealer Solution Network (DSN).