C1.7 and C2.2 Industrial Engine Caterpillar

Motorized Valve - Test

Usage:

C1.7 G34

This procedure covers the following codes:

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Table 1
Diagnostic Codes for the Motorized Valves
J1939 Code	Code Description	Comments
2791 -3	Engine Exhaust Gas Recirculation (EGR) Valve Control : Voltage Above Normal	The ECM detects the following conditions: A high-voltage condition exists in the output for the NOx Reduction System (NRS) valve (EGR valve) for 2 seconds 168 diagnostic codes are not active. The ECM has been powered for at least 2 seconds. The warning lamp will come on. The ECM will log the diagnostic code.
2791-10	Engine Exhaust Gas Recirculation (EGR) Valve Control : Abnormal Rate of Change	The ECM detects the following conditions: The NRS valve (EGR valve) is not responding as expected. The ECM has been powered for at least 2 seconds. The warning lamp will come on. The ECM will log the diagnostic code.
2950-2	Engine Intake Valve Actuator #1 : Erratic, Intermittent, or Incorrect (If equipped)	The ECM detects the following conditions: The signal to the intake throttle valve is not as expected. The ECM has been powered for at least 2 seconds. The warning lamp will come on. The ECM will log the diagnostic code.
2950-7	Engine Intake Valve Actuator #1 : Not Responding Properly (If equipped)	The ECM detects the following conditions: The position of the intake throttle valve is not as expected. The ECM has been powered for at least 2 seconds. The warning lamp will come on. The ECM will log the diagnostic code.

The following background information is related to this procedure:

NRS valve (EGR valve)

The NRS valve (EGR valve) is used to control the amount of exhaust gas which is recirculated into the intake manifold.

The amount of exhaust gas that is required is calculated by the software that is contained in the ECM.

The NRS valve is controlled by a PWM signal from the ECM.

EGR Valve Control Override Test

The EGR Valve Control Override Test will identify whether the NRS valve is working correctly. This test must be run when the engine speed is zero and the battery voltage is within an acceptable range. The service test must only be executed if the battery voltage is between 9VDC and 16VDC.If the battery voltage is outside of this range at any time, the test must be aborted. The test will also be aborted if a position sensor diagnostic, a motor short diagnostic, or a motor open circuit diagnostic become active.

If at any point during the test the engine speed is not zero, the test will abort. The test moves the valve to various positions and then checks the position sensor within the valve to confirm that the valve has responded correctly. If a test threshold is exceeded or any related diagnostics become active, the test will abort and generate an error identifier.

Intake Throttle Valve (If Equipped)

When necessary, the engine intake throttle valve reduces the intake manifold pressure so that the pressure in the NRS mixer is always higher. This pressure differential ensures that recirculated exhaust gases will flow into the intake manifold.

The engine intake throttle valve is controlled by a PWM signal from the ECM.

Intake Throttle Valve Override Test

The Intake Throttle Valve Override Test will identify whether the intake throttle valve is working correctly. This test must be run when the engine speed is zero and the battery voltage is within an acceptable range. The service test must only be executed if the battery voltage is between 9VDC and 16VDC. If the battery voltage is outside of this range at any time, the test must be aborted. The test will also be aborted if a position sensor diagnostic, a motor short diagnostic, or a motor open circuit diagnostic become active.

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Illustration 1	g06088272
Schematic for the motorized valves

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Illustration 2	g03833072
Connector on the NRS valve (1) Motor - (2) + 5 VDC (3) Ground (4) Position signal (5) Motor +

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Illustration 3	g03833076
Connector on the intake throttle valve (if equipped) (1) Motor - (2) Motor + (3) Ground (4) Not used (5) + 5 VDC (6) Position signal

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Illustration 4	g03833114
Engine interface connector (39) Intake throttle valve PWM return (40) NRS valve PWM return (41) Intake throttle valve PWM power (42) NRS valve PWM power

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

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Turn the keyswitch to the OFF position. B. Thoroughly inspect the connectors for the motorized valves. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the motorized valves. D. Check the harness and wiring for abrasion and for pinch points from the motorized valves to the ECM.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. Proceed to Test Step 2.
2. Check for Diagnostic Codes 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. Monitor the electronic service tool for active diagnostic codes and/or logged diagnostic codes.	Diagnostic codes	Result: A 2791-X diagnostic code is active or recently logged. Proceed to Test Step 3. Result: A 2950-X diagnostic code is active or recently logged. Proceed to Test Step 6. Result: No diagnostic codes are active or logged. Repair: For intermittent faults, refer to Troubleshooting, "Electrical Connectors - Inspect". If no intermittent faults are found, proceed to Test Step 9.
3. Check the NRS Valve A. Turn the keyswitch to the OFF position. B. Disconnect the NRS valve from the engine harness. C. Measure the resistance between pin 1 and pin 5 on the NRS valve. Refer to Illustration 2.	0.3 Ohms to 100 Ohms	Result: The resistance measurement is less than 0.3 Ohms or more than 100 Ohms. Repair: Install a replacement NRS valve. Proceed to Test Step 9. Result: The resistance measurement is between 0.3 Ohms and 100 Ohms. Proceed to Test Step 4.
4. Check the Wiring between the NRS Valve and the ECM for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the engine interface connector. C. Disconnect the J1 connector from the ECM. D. Measure the resistance between the following pairs of pins: · Pin 1 on the valve harness connector and pin 40 on the engine interface connector. Refer to Illustration 2 and Illustration 4. · Pin 40 on the engine interface connector and J1:45. Refer to Illustration 4 and Troubleshooting, "Electrical Connectors". · Pin 5 on the valve harness connector and pin 42 on the engine interface connector. Refer to Illustration 2 and Illustration 4. · Pin 42 on the engine interface connector and J1:58. Refer to Illustration 4 and Troubleshooting, "Electrical Connectors".	Less than 2.0 Ohms	Result: One of the resistance measurements is more than 2.0 Ohms. Repair: Repair or replace the wiring harness. Proceed to Test Step 9. Result: All the resistance measurements are less than 2.0 Ohms. Proceed to Test Step 5.
5. Check the Wiring between the NRS Valve and the ECM for a Short Circuit Refer to Illustration 4. A. Measure the resistance between the following pins: · Pin 40 on the valve side of the engine interface connector and all other pins on the connector. · Pin 40 on the ECM side of the engine interface connector and all other pins on the connector. · Pin 42 on the valve side of the engine interface connector and all other pins on the connector. · Pin 42 on the ECM side of the engine interface connector and all other pins on the connector.	More than 1k Ohm	Result: One of the resistance measurements is less than 1k Ohm. Repair: Repair or replace the wiring harness. Proceed to Test Step 9. Result: All the resistance measurements are more than 1k Ohms. Contact the Dealer Solutions Network (DSN).
6. Check the Intake Throttle Valve A. Turn the keyswitch to the OFF position. B. Disconnect the intake throttle valve from the engine harness. C. Measure the resistance between pin 1 and pin 2 on the intake throttle valve. Refer to Illustration 3.	0.3 Ohms to 100 Ohms	Result: The resistance measurement is less than 0.3 Ohms or more than 100 Ohms. Repair: Install a replacement intake throttle valve. Proceed to Test Step 9. Result: The resistance measurement is between 0.3 Ohms and 100 Ohms. Proceed to Test Step 7.
7. Check the Wiring between the Intake Throttle Valve and the ECM for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the engine interface connector. C. Disconnect the J1 connector from the ECM. D. Measure the resistance between the following pairs of pins: · Pin 1 on the valve harness connector and pin 39 on the engine interface connector. Refer to Illustration 3 and Illustration 4. · Pin 39 on the engine interface connector and J1:44. Refer to Illustration 4 and Troubleshooting, "Electrical Connectors". · Pin 2 on the valve harness connector and pin 41 on the engine interface connector. Refer to Illustration 3 and Illustration 4. · Pin 41 on the engine interface connector and J1:57. Refer to Illustration 4 and Troubleshooting, "Electrical Connectors".	Less than 2.0 Ohms	Result: One of the resistance measurements is more than 2.0 Ohms. Repair: Repair or replace the wiring harness. Proceed to Test Step 9. Result: All the resistance measurements are less than 2.0 Ohms. Proceed to Test Step 8.
8. Check the Wiring between the Intake Throttle Valve and the ECM for a Short Circuit Refer to Illustration 4. A. Measure the resistance between the following pins: · Pin 39 on the valve side of the engine interface connector and all other pins on the connector. · Pin 39 on the ECM side of the engine interface connector and all other pins on the connector. · Pin 41 on the valve side of the engine interface connector and all other pins on the connector. · Pin 41 on the ECM side of the engine interface connector and all other pins on the connector.	More than 1k Ohm	Result: One of the resistance measurements is less than 1k Ohm. Repair: Repair or replace the wiring harness. Proceed to Test Step 9. Result: All the resistance measurements are more than 1k Ohms. Contact the Dealer Solutions Network (DSN).
9. Perform the Valve Override Test A. Reconnect the harness connector to the valve. B. Reconnect the engine interface connector. C. Reconnect the J1 connector to the ECM. D. Connect the electronic service tool to the diagnostic connector. E. Turn the keyswitch to the ON position. F. For the NRS valve, use the electronic service tool to perform the "EGR Valve Override Test". Check that the actual valve position matches the desired position during the override test cycle. G. For the intake throttle valve, use the electronic service tool to perform the "Intake Throttle Valve Override Test". Check that the actual valve position matches the desired position during the override test cycle.	Valve test	Result: The valve test is OK. Repair: Use the electronic service tool to clear any logged codes and then return the unit to service. Result: The valve test is not OK. Contact the Dealer Solutions Network (DSN).