C7.1 Engines and Generator Sets Caterpillar

Motorized Valve - Test

Usage:

C7.1 770

This procedure covers the following codes:

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Table 1
Diagnostic Codes for the Motorized Valves
J1939 Code	CDL Code	Code Description	Comments
2791 -5	3405-5	Engine Exhaust Gas Recirculation (EGR) Valve Control : Current Below Normal	The ECM detects the following conditions: A low current condition 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. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
2791-6	3405-6	Engine Exhaust Gas Recirculation (EGR) Valve Control : Current Above Normal	The ECM detects the following conditions: A high current condition in the output for the NRS valve (EGR valve) for 2 seconds The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
2791-7	E1121 (2)	EGR Valve Control Not Responding to Command	The ECM detects the following conditions: The signal from the NRS valve position sensor indicates that the valve is not in the desired position. This diagnostic code can be caused by a loss of the 5 VDC supply to the NRS valve position sensor. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3464 -5	3514-5	Engine Throttle Actuator 1 Control Command : Current Below Normal	The ECM detects the following conditions: A low current condition in the output for the engine intake throttle valve for 2 seconds 168 diagnostic codes are not active. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3464-6	3514-6	Engine Throttle Actuator 1 Control Command : Current Above Normal	The ECM detects the following conditions: A high current condition in the output for the engine intake throttle valve for 2 seconds The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3464-7	E1262 (2)	Engine Throttle Actuator 1 Control Command : Not Responding Properly	The ECM detects the following conditions: The signal from the engine intake throttle valve position sensor indicates that the valve is not in the desired position. This diagnostic code can be caused by a loss of the 5 VDC supply to the engine intake throttle valve position sensor. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3487-5	2489-5	Aftertreatment #1 Air Pressure Control : Current Below Normal	The ECM detects the following conditions: A low current condition in the output for the combustion air valve for 2 seconds The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3487-6	2489-6	Aftertreatment #1 Air Pressure Control : Current Above Normal	The ECM detects the following conditions: A high current condition in the output for the combustion air valve for 2 seconds The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
3487-7	E1041 (2)	Aftertreatment #1 Air Pressure Control : Not Responding Properly	The ECM detects the following conditions: The signal from the combustion air valve position sensor indicates that the valve is not in the desired position. This diagnostic code can be caused by a loss of the 5 VDC supply to the engine intake throttle valve position sensor. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.

The following background information is related to this procedure:

ARD combustion air valve

The Aftertreatment Regeneration Device (ARD) increases the exhaust gas temperature to burn off the soot that is collected in the DPF. The ARD requires a supply of fuel and clean air. The air supply is regulated by the ARD combustion air valve.

The amount of air that is required by the ARD is calculated by the software that is contained in the ECM. The combustion air valve is controlled by a PWM signal from the ECM.

NRS valve (EGR valve) and engine intake throttle 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.

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

Air System Motor Valves Verification Test

The Air System Motor Valve Verification Test will identify whether the EGR valve, and the EBPR are working correctly. This test must be run when the engine speed is zero and the battery voltage is within an acceptable range. For a 12VDC system, the service test must only be executed if the battery voltage is between 9VDC and 16VDC. For a 24VDC system, the battery voltage must be between 18VDC and 32VDC. If the battery voltage is outside of these ranges 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 valves to various positions and then checks the position sensor within each valve to confirm that the valve has responded correctly. Each valve will be tested in turn, starting with the EGR valve. If a test threshold is exceeded or any related diagnostics become active, the test will abort and generate an error identifier.

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Illustration 1	g06152771
Schematic for the motorized valves

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Illustration 2	g02009195
Typical view of the pin locations on the P2 connector for the motorized valves (1) Engine intake throttle valve return (2) Engine intake throttle valve signal (32) NRS valve return (40) NRS valve signal (45) Combustion air valve position sensor 5 VDC supply (46) NRS valve/intake throttle valve position sensor 5 VDC supply (55) Combustion air valve position sensor ground (56) NRS valve/intake throttle valve position sensor ground (48) Combustion air valve return (58) Combustion air valve signal

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Illustration 3	g02315693
Typical example of the connector for the combustion air valve (1) Position sensor 5 VDC supply (2) Position sensor return (4) Combustion air valve ground (6) Combustion air valve signal

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Illustration 4	g02315694
Typical example of the connector for the engine intake throttle valve (1) Engine intake throttle valve supply (2) Engine intake throttle valve return (3) Position sensor ground (5) Position sensor 5 VDC supply

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Illustration 5	g02315757
Typical example of the connector for the NRS valve (1) Position sensor 5 VDC supply (2) Position sensor ground (4) NRS valve return (6) NRS valve signal

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. 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 screw for the ECM connector for the correct torque of 6 N·m (53 lb in). E. 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: An XXXX-5 diagnostic code is active or recently logged for one or more of the motorized valves. Proceed to Test Step 6. Result: An XXXX-6 diagnostic code is active or recently logged for one or more of the motorized valves. Proceed to Test Step 8. Result: An XXXX-7 (EXXXX-2) code is active or recently logged for one or more of the motorized valves. Proceed to Test Step 3. Result: No diagnostic codes are active or logged. Repair: For intermittent faults, refer to Troubleshooting, "Electrical Connectors - Inspect". If no intermittent faults are found, return the unit to service.
3. Measure the Sensor Supply Voltage at the Valve Connector A. Turn the keyswitch to the OFF position. B. Disconnect the suspect valve from the engine harness. C. Turn the keyswitch to the ON position. D. Measure the voltage at the harness connector for the valve from the 5 VDC supply terminal of the position sensor to the sensor ground terminal. E. Turn the keyswitch to the OFF position.	4.84 to 5.16 VDC	Result: The voltage from the terminal for the 5 VDC supply to the sensor common terminal measures 4.84 to 5.16 VDC. Repair: Reconnect the suspect valve. Operate the engine for enough time to allow the engine to reach normal operating temperature. The suspect valve may be not responding due to frozen condensation. Use the electronic service tool to run the "Air System Motor Valves Verification Test". If the fault is cleared, return the engine to service. If the -7(EXXXX (2)) code is still active, replace the suspect valve. Refer to Disassembly and Assembly for more information. Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: A 2791-7 (E1121 (2)) or a 3464-7 (E1262 (1)) diagnostic code is active. The fault is in the 5 VDC supply wire or the ground wire in the engine harness. Repair: Repair the faulty wiring or replace the faulty harness. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 3487-7 (E1041 (2)) diagnostic code is active. Reconnect the valve connector. Proceed to Test Step 4.
4. Measure the Sensor Supply Voltage at the 40-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 40-pin connector. C. Turn the keyswitch to the ON position. D. Measure the voltage at the 40-pin connector on the link harness from pin 1 to pin 2. E. Turn the keyswitch to the OFF position.	4.84 to 5.16 VDC	Result: The voltage from the terminal for the 5 VDC supply to the sensor common terminal measures 4.84 to 5.16 VDC. The fault is in the CEM harness. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to run the "Air System Motor Valves Verification Test". If the fault is cleared, return the engine to service. If the 3487-7 (E1041 (2)) code is still active, replace the suspect valve. Refer to Disassembly and Assembly for more information. Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The sensor supply voltage is out of the nominal range. Reconnect the 40-pin connector. Proceed to Test Step 5.
5. Measure the Sensor Supply Voltage at the 31-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 31-pin connector. C. Turn the keyswitch to the ON position. D. Measure the voltage at the 31-pin connector on the ECM harness from pin 1 to pin 2. E. Turn the keyswitch to the OFF position.	4.84 to 5.16 VDC	Result: The voltage from the terminal for the 5 VDC supply to the sensor common terminal measures 4.84 to 5.16 VDC. The fault is in the link harness. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to run the "Air System Motor Valves Verification Test". Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The sensor supply voltage is out of the nominal range. The fault is in the ECM harness. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to run the "Air System Motor Valves Verification Test". Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
6. Create a Short Circuit at the Valve Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect valve. C. Fabricate a jumper wire that is 150 mm (6 inch) long. D. Install the jumper between the signal and return pins on the connector for the suspect valve to create a short circuit. E. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. F. Remove the jumper wire from the connector for the motorized valve.	Open circuit	Result: Diagnostic code XXXX-6 is active when the jumper wire is installed. Diagnostic code XXXX-5 is active with the jumper removed. Repair: Reconnect the valve. Check for active diagnostic codes on the electronic service tool. Wait at least 30 seconds in order for the codes to be displayed. If the XXXX-5 diagnostic code returns, then replace the valve. Refer to Disassembly and Assembly for the correct procedure. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 2791-5 (3405-6) or a 3464-5 (3514-6) diagnostic code is still active with the jumper installed. Proceed to Test Step 12. Result: A 3487-5 (2489-5) diagnostic code is still active with the jumper installed. Proceed to Test Step 7.
7. Create a Short Circuit at the 40-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 40-pin connector for the suspect valve. C. Fabricate a jumper wire that is 150 mm (6 inch) long. D. Install the jumper between pins 11 and 12 on the link harness connector. E. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. F. Remove the jumper wire from the connector.	Open circuit	Result: Diagnostic code 3487-6 is active when the jumper wire is installed. Diagnostic code 3487-5 is active with the jumper removed. The fault is in the CEM harness Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to run the "Air System Motor Valves Verification Test". Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: Diagnostic code 3487-5 is still active with the jumper installed. – The CEM harness is OK. Proceed to Test Step 8.
8. Create a Short Circuit at the 31-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 31-pin connector for the suspect valve. C. Fabricate a jumper wire that is 150 mm (6 inch) long. D. Install the jumper between pins 11 and 12 on the ECM harness connector. E. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. F. Remove the jumper wire from the connector.	Open circuit	Result: Diagnostic code 3487-6 is active when the jumper wire is installed. Diagnostic code 3487-5 is active with the jumper removed. The fault is in the link harness Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to run the "Air System Motor Valves Verification Test". Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: Diagnostic code 3487-5 is still active with the jumper installed. – The link harness is OK. Proceed to Test Step 12.
9. Create an Open Circuit at the Valve Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect valve to create an open circuit. C. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. Wait at least 30 seconds in order for the codes to be displayed.	Motorized valve	Result: An XXXX-5 diagnostic code is now active. There is a short in the valve. Repair: Reconnect the valve. Check for active diagnostic codes on the electronic service tool. Wait at least 30 seconds in order for the codes to be displayed. If the XXXX-6 diagnostic code returns, then replace the valve. Refer to Disassembly and Assembly for the correct procedure. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 2791-6 (3405-6) or a 3464-6 (3514-6) diagnostic code is active. The fault is in the 5 VDC supply wire or the ground wire in the engine harness. Repair: Repair the faulty wiring or replace the faulty harness. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 3487-6 (2489-6) diagnostic code is active. The combustion air valve is OK. Reconnect the valve connector. Proceed to Test Step 10.
10. Create an Open Circuit at the 40-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 40-pin connector. C. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. Wait at least 30 seconds in order for the codes to be displayed. Note: While the 40-pin connector is disconnected, diagnostic codes for the other components that are connected to the 40-pin connector will be active. Disregard the diagnostic codes for all the other components. Only address the 3487(2489) diagnostic codes.	Motorized valve	Result: A 3487-5 diagnostic code is now active. There is a short in the CEM harness. Repair: Repair the faulty wiring or replace the faulty harness. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 3487-6 (2489-6) diagnostic code is active. The CEM harness is OK. Reconnect the 40-pin connector. Proceed to Test Step 11.
11. Create an Open Circuit at the 31-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 31-pin connector. C. Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool. Wait at least 30 seconds in order for the codes to be displayed. Note: While the 31-pin connector is disconnected, diagnostic codes for the other components that are connected to the 31-pin connector will be active. Disregard the diagnostic codes for all the other components. Only address the 3487(2489) diagnostic codes.	Motorized valve	Result: A 3487-5 diagnostic code is now active. There is a short in the link harness. Repair: Repair the faulty wiring or replace the faulty harness. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 3487-6 (2489-6) diagnostic code is active. The link harness is OK. Reconnect the 31-pin connector. Proceed to Test Step 12.
12. Bypass the Engine Wiring Harness For a 2791 (3405) or a 3464 (3514) diagnostic code, perform steps A. to H. and continue from step P. For a 3487 (2489) diagnostic code, perform steps I. to O. and continue from step P. A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector and the connector for the suspect valve. C. Remove the signal wire and the return wire for the suspect valve from the P2 connector. D. Remove the signal wire and the return wire from the connector for the suspect valve. E. Fabricate two jumper wires that are long enough to reach from the ECM to the connector for the suspect valve. F. Insert one end of a jumper into the plug for the supply wire on the P2 connector. Insert the other end of the jumper into the plug for the supply wire on the connector for the suspect valve. G. Insert one end of the other jumper into the plug for the return wire on the P2 connector. Insert the other end of the jumper into the plug for the return wire on the connector for the suspect valve. H. Reconnect the P2 connector and the connector for the valve. I. Disconnect the P2 connector and the 31-pin connector. J. Remove the wires from P2:48 and P2:58. K. Remove the wires from pins 11 and 12 on the 31-pin connector. L. Fabricate two jumper wires that are long enough to reach from the ECM to the 31-pin connector. M. Insert one end of a jumper into P2:48. Insert the other end of the jumper into socket 12 on the 31-pin connector. N. Insert one end of the other jumper into P2:58. Insert the other end of the jumper into socket 11 on the 31-pin connector. O. Reconnect the P2 connector and the 31-pin connector. P. Turn the keyswitch to the ON position. Q. Use the electronic service tool to monitor the "Active Diagnostic Code" screen. Check for either the open circuit diagnostic code for the suspect valve or the short circuit diagnostic code for the suspect valve. R. Remove the jumpers and reconnect the wires that were previously removed. S. Reconnect the connectors.	Wiring bypass	Result: The diagnostic code disappears when the jumpers are installed. There is a fault in the engine wiring harness. Repair: Repair the faulty harness or replace the faulty harness. Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The diagnostic code is still present with the jumpers installed Contact the Dealer Solutions Network (DSN).