This procedure covers the following codes:
| Diagnostic Trouble Codes for the Motorized Valves | ||
|---|---|---|
| J1939 Code | Description | Notes |
| 2791-5 | 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 | 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 | Engine Exhaust Gas Recirculation (EGR) Valve Control : Not Responding Properly | 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 | 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 | 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 | 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 | Afterreatment #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 | 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 | 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 in order 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 and the engine intake throttle valve are 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 | g02364276 |
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 | |
Test Step 1. Inspect Electrical Connectors and Wiring
- Thoroughly inspect connectors for the motorized valves. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Thoroughly inspect the 31-pin connector and the 40-pin connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the motorized valves.
- Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in).
Results:
- All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, abrasion, and pinch points - Proceed to Test Step 2.
- There is a fault in the connectors and/or the harness. -
Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
STOP
Test Step 2. Check for Diagnostic Codes
- Turn the keyswitch to the OFF position.
- Connect the electronic service tool to the diagnostic connector.
- Turn the keyswitch to the ON position.
- Download the following items before performing any troubleshooting or clearing any diagnostic codes:
- Warranty Report
- Aftertreatment Regeneration Trigger History
- Product Status Report with Histograms
- Warranty Report
- Monitor the electronic service tool for active diagnostic codes and/or logged diagnostic codes.
Expected Result:
One or more of the codes that are listed in Table 1 is active or recently logged.
Results:
- An XXXX-5 diagnostic code is active or recently logged for one or more of the motorized valves - Proceed to Test Step 6.
- An XXXX-6 diagnostic code is active or recently logged for one or more of the motorized valves - Proceed to Test Step 9.
- An XXXX-7 diagnostic code is active or recently logged for one or more of the motorized valves - Proceed to Test Step 3.
- No Codes - The fault seems to be resolved.
Repair: For intermittent faults, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
Test Step 3. Measure the Sensor Supply Voltage at the Valve Connector
- Turn the keyswitch to the OFF position.
- Disconnect the suspect valve from the engine harness.
- Turn the keyswitch to the ON position.
- 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.
Expected Result:
The voltage measures 4.84 to 5.16 VDC.
Results:
- The voltage from the terminal for the 5 VDC supply to the sensor common terminal measures 4.84 to 5.16 VDC. - The sensor supply voltage is correct.
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 code is still active, replace the suspect valve. Refer to Disassembly and Assembly for more information.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
STOP
- The sensor supply voltage is out of the nominal range. A 2791-7 or a 3464-7 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 wiring.Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
STOP
- The sensor supply voltage is out of the nominal range. A 3487-7 diagnostic code is active. - Reconnect the valve connector. Proceed to Test Step 4.
Test Step 4. Measure the Sensor Supply Voltage at the 40-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 40-pin connector.
- Turn the keyswitch to the ON position.
- Measure the voltage at the 40-pin connector on the CEM harness from pin 1 to pin 2.
Expected Result:
The voltage measures 4.84 to 5.16 VDC.
Results:
- OK - The voltage is within the expected range. The fault is in the CEM harness.
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.
STOP
- Not OK - The voltage is not within the expected range. The CEM harness is OK. Reconnect the 40-pin connector. Proceed to Test Step 5.
Test Step 5. Measure the Sensor Supply Voltage at the 31-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 31-pin connector.
- Turn the keyswitch to the ON position.
- Measure the voltage at the 31-pin connector on the harness between the engine and the CEM from pin 1 to pin 2.
Expected Result:
The voltage measures 4.84 to 5.16 VDC.
Results:
- OK - The voltage is within the expected range. The fault is in the harness between the 40-pin connector and the 31-pin connector.
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.
STOP
- Not OK - The voltage is not within the expected range. The fault is in the engine harness.
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.
STOP
Test Step 6. Create a Short Circuit at the Valve Connector
- Turn the keyswitch to the OFF position.
- Disconnect the connector for the suspect valve.
- Fabricate a jumper wire that is 150 mm (6 inch) long.
- Install the jumper between the signal and return pins on the connector for the suspect valve in order to create a short circuit.
- Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool.
- Remove the jumper wire from the connector for the motorized valve.
Results:
- Diagnostic code XXXX-6 is active when the jumper wire is installed. Diagnostic code XXXX-5 is active with the jumper removed. -
Repair: Perform the following 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.
STOP
- A 2791-5 or a 3464-5 diagnostic code is still active with the jumper installed. - The valve is OK. Proceed to Test Step 12.
- A 3487-5 diagnostic code is still active with the jumper installed - The combustion air valve is OK. Proceed to Test Step 7.
Test Step 7. Create a Short Circuit at the 40-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 40-pin connector.
- Fabricate a jumper wire that is 150 mm (6 inch) long.
- Install the jumper on the 40-pin connector on the harness between the CEM and the engine between socket 11 and socket 12.
- Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool.
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 diagnostic codes.
- Remove the jumper wire from the 40-pin connector.
Results:
- 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 clear all logged diagnostic codes and verify that the repair eliminates the fault.
STOP
- Diagnostic code 3487-5 is still active with the jumper installed. - The CEM harness is OK. Proceed to Test Step 8.
Test Step 8. Create a Short Circuit at the 31-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 31-pin connector.
- Fabricate a jumper wire that is 150 mm (6 inch) long.
- Install the jumper on the 31-pin connector on the engine harness between socket 11 and socket 12 in order to create a short circuit.
- Turn the keyswitch to the ON position. Check for active diagnostic codes on the electronic service tool.
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 diagnostic codes.
- Remove the jumper wire from the 31-pin connector.
Results:
- 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 harness between the 40-pin connector and the 31-pin connector.
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.
STOP
- Diagnostic code 3487-5 is still active with the jumper installed. - The harness between the 40-pin connector and the 31-pin connector is OK. Proceed to Test Step 12.
Test Step 9. Create an Open Circuit at the Valve Connector
- Turn the keyswitch to the OFF position.
- Disconnect the connector for the suspect valve in order to create an open circuit.
- 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.
Results:
- An XXXX-5 diagnostic code is now active - There is a short in the valve.
Repair: Perform the following 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.
STOP
- There is still a 2791-6 or a 3464-6 diagnostic code. - The valve is OK. Proceed to Test Step 12.
- There is still a 3487-6 diagnostic code. - The combustion air valve is OK. Proceed to Test Step 10.
Test Step 10. Create an Open Circuit at the 40-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 40-pin connector.
- 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 diagnostic codes.
Results:
- 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 wiring.Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
STOP
- The 3487-6 diagnostic code is still active. - The CEM harness is OK. Proceed to Test Step 11.
Test Step 11. Create an Open Circuit at the 31-Pin Connector
- Turn the keyswitch to the OFF position.
- Disconnect the 31-pin connector.
- 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 diagnostic codes.
Results:
- A 3487-5 diagnostic code is now active. - There is a short in the harness between the 40-pin connector and the 31-pin connector.
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.
STOP
- The 3487-6 diagnostic code is still active. - The harness between the 40-pin connector and the 31-pin connector is OK. Proceed to Test Step 12.
Test Step 12. Bypass the Engine Wiring Harness
- Turn the keyswitch to the OFF position.
- For a 2791 or a 3464 diagnostic code, perform the following steps:
- Disconnect the P2 connector and the connector for the suspect valve.
- Remove the signal wire and the return wire for the suspect valve from the P2 connector.
- Remove the signal wire and the return wire from the connector for the suspect valve.
- Fabricate two jumper wires that are long enough to reach from the ECM to the connector for the suspect valve.
- 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.
- 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.
- Reconnect the P2 connector and the connector for the valve.
- For a 3487 diagnostic code, perform the following steps:
- Disconnect the P2 connector and the 31-pin connector.
- Remove the wires from P2:48 and P2:58.
- Remove the wires from pins 11 and 12 on the 31-pin connector.
- Fabricate two jumper wires that are long enough to reach from the ECM to the 31-pin connector.
- Insert one end of a jumper into P2:48. Insert the other end of the jumper into socket 12 on the 31-pin connector.
- 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.
- Reconnect the P2 connector and the 31-pin connector.
- Turn the keyswitch to the ON position.
- Use the electronic service tool in order 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.
- Remove the jumpers and reconnect the wires that were previously removed.
- Reconnect the connectors.
Results:
- 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 in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
STOP
- The diagnostic code is still present with the jumpers installed -
Repair: Perform the following repair:
- Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".
- Contact the Technical Communicator at a Caterpillar dealer.
Note: This consultation can greatly reduce the repair time.
- If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".
- Use the electronic service tool to recheck the system for active diagnostic codes.
- If the fault is resolved with the test ECM, reconnect the suspect ECM.
- If the fault returns with the suspect ECM, replace the ECM.
- Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
STOP