C1.7 and C2.2 Industrial Engine Caterpillar

Valve Position - Test

Usage:

C1.7 G34

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Codes for the Valve Position Sensors
J1939 Code	Code Description	Comments
27-3	EGR #1 Valve Position : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the position sensor on the NOx Reduction System (NRS) valve is greater than 4.8 VDC for 0.5 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed when the code is active. The engine will be derated.
27-4	EGR #1 Valve Position : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the NRS valve position sensor is less than 0.22 VDC for 0.5 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed when the code is active. The engine will be derated.
27-7	EGR #1 Valve Position : Not Responding Properly	The ECM detects the following conditions: The signal voltage from the NRS valve position sensor is erratic or intermittent. The warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed when the code is active. The engine will be derated.
51-3	Engine Throttle Position : Voltage Above Normal (If Equipped)	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the position sensor on the intake throttle valve is greater than 4.75 VDC for 0.5 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed when the code is active. The engine will be derated.
51-4	Engine Throttle Position : Voltage Below Normal (If Equipped)	The ECM detects the following conditions: The signal voltage from the intake throttle valve position sensor is less than 0.25 VDC for 0.5 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed when the code is active. The engine will be derated.
Follow the troubleshooting procedure to identify the root cause of the fault.

The following conditions must exist before any of the preceding codes will become active:

The ECM has been powered for at least 2 seconds.
There are no active 168 codes.
There are no active 3509 codes.

Use this procedure to troubleshoot the position sensors for the following valves:

NRS valve
Intake throttle valve (if equipped)

Each position sensor is integral in the associated valve. If the following procedure indicates a fault with the position sensor, then the entire valve must be replaced.

The following background information is related to this procedure:

The troubleshooting procedures for the diagnostic codes of each position sensor are identical. The 5 VDC sensor supply provides power to all 5 VDC sensors. The ECM supplies 5.0 VDC to terminal "2" of the NRS valve connector and terminal "5" of the intake throttle valve connector. The sensor common from the ECM connector goes to terminal "3" of both valve connectors. The signal voltage from terminal "4" of NRS valve is supplied to P2:33. The signal voltage from terminal "6" of intake throttle valve is supplied to P2:63.

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Illustration 1	g06088281
Schematic diagram for the valve position sensors

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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	g03838959
Engine interface connector (5) Sensor ground (12) NRS valve +5 VDC (14) Intake throttle valve +5 VDC (if equipped) (18) NRS valve position signal (31) Intake throttle valve position signal (if equipped)

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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. Inspect the connectors for the valve position sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect". C. Perform a 45 N (10 lb) pull test on each of the wires in the suspect sensor connector and the sensor connections at the ECM. D. Check the ground connection on the ECM for abrasions and pinch points. E. Check the harness for abrasion and pinch points from the suspect sensor 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 Active 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. Wait at least 10 seconds for activation of the diagnostic codes. D. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes. E. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: A 27-X diagnostic code is active or recently logged. Proceed to Test Step 3. Result: A 51-X diagnostic code is active or recently logged. Proceed to Test Step 6.
3. Measure the Supply Voltage at the NRS Valve Connector A. Turn the keyswitch to the OFF position. B. Disconnect the NRS valve from the harness. C. Turn the keyswitch to the ON position. D. Measure the voltage between terminals 2 and 3 at the connector for the valve. E. Reconnect the valve to the harness.	4.8 VDC to 5.2 VDC	Result: The sensor supply voltage is out of the nominal range. The fault is in the engine harness between the valve connector and the ECM. Repair: Repair the faulty valve connector 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: The sensor supply voltage is correct. Proceed to Test Step 4.
4. Check the Wiring for the NRS Valve for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the NRS valve. C. Disconnect the engine interface connector. D. Disconnect the P2 connector from the ECM. E. Measure the following resistances: · Pin 2 on the NRS valve harness connector to pin 12 on the valve side of the engine interface connector. · Pin 3 on the NRS valve harness connector to pin 5 on the valve side of the engine interface connector. · Pin 4 on the NRS valve harness connector to pin 18 on the valve side of the engine interface connector. · Pin 12 on the ECM side of the engine interface connector to P2:22. · Pin 5 on the ECM side of the engine interface connector to P2:12. · Pin 18 on the ECM side of the engine interface connector to P2:33. F. Reconnect the P2 connector to the ECM. G. Reconnect the engine interface connector. H. Reconnect the harness connector to the NRS valve.	Less than 2.0 Ohms	Result: A resistance measurement is more than 2.0 Ohms. Repair or replace the harness between the ECM and the valve. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are less than 2.0 Ohms. Proceed to Test Step 5.
5. Check the Wiring for the NRS Valve for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the NRS valve. C. Disconnect the engine interface connector. D. Disconnect the P2 connector from the ECM. E. Measure the following resistances: · Pin 12 on the valve side of the engine interface connector to all other pins on the connector. · Pin 5 on the valve side of the engine interface connector to all other pins on the connector. · Pin 18 on the valve side of the engine interface connector to all other pins on the connector. · Pin 12 on the ECM side of the engine interface connector to all other pins on the connector. · Pin 5 on the ECM side of the engine interface connector to all other pins on the connector. · Pin 18 on the ECM side of the engine interface connector to all other pins on the connector. F. Reconnect the P2 connector to the ECM. G. Reconnect the engine interface connector. H. Reconnect the harness connector to the NRS valve.	More than 1k Ohms	Result: A resistance measurement is less than 1k Ohms. Repair or replace the harness between the ECM and the valve. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are more than 1k Ohms. Contact the Dealer Solutions Network (DSN).
6. Measure the Supply Voltage at the Intake Throttle Valve Connector A. Turn the keyswitch to the OFF position. B. Disconnect the intake throttle valve from the harness. C. Turn the keyswitch to the ON position. D. Measure the voltage between terminals 3 and 5 at the connector for the valve. E. Reconnect the valve to the harness.	4.8 VDC to 5.2 VDC	Result: The sensor supply voltage is out of the nominal range. The fault is in the engine harness between the valve connector and the ECM. Repair: Repair the faulty valve connector 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: The sensor supply voltage is correct. Proceed to Test Step 7.
7. Check the Wiring for the Intake Throttle Valve for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the intake throttle valve. C. Disconnect the engine interface connector. D. Disconnect the P2 connector from the ECM. E. Measure the following resistances: · Pin 5 on the intake throttle valve harness connector to pin 14 on the valve side of the engine interface connector. · Pin 6 on the intake throttle valve harness connector to pin 31 on the valve side of the engine interface connector. · Pin 3 on the intake throttle valve harness connector to pin 5 on the valve side of the engine interface connector. · Pin 14 on the ECM side of the engine interface connector to P2:24. · Pin 31 on the ECM side of the engine interface connector to P2:63. · Pin 5 on the ECM side of the engine interface connector to P2:12. F. Reconnect the P2 connector to the ECM. G. Reconnect the engine interface connector. H. Reconnect the harness connector to the intake throttle valve.	Less than 2.0 Ohms	Result: A resistance measurement is more than 2.0 Ohms. Repair or replace the harness between the ECM and the valve. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are less than 2.0 Ohms. Proceed to Test Step 8.
8. Check the Wiring for the Intake Throttle Valve for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the intake throttle valve. C. Disconnect the engine interface connector. D. Disconnect the P2 connector from the ECM. E. Measure the following resistances: · Pin 14 on the valve side of the engine interface connector to all other pins on the connector. · Pin 31 on the valve side of the engine interface connector to all other pins on the connector. · Pin 5 on the valve side of the engine interface connector to all other pins on the connector. · Pin 14 on the ECM side of the engine interface connector to all other pins on the connector. · Pin 31 on the ECM side of the engine interface connector to all other pins on the connector. · Pin 5 on the ECM side of the engine interface connector to all other pins on the connector. F. Reconnect the P2 connector to the ECM. G. Reconnect the engine interface connector. H. Reconnect the harness connector to the Intake throttle valve.	More than 1k Ohms	Result: A resistance measurement is less than 1k Ohms. Repair or replace the harness between the ECM and the valve. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are more than 1k Ohms. Contact the Dealer Solutions Network (DSN).