This test procedure is used for the Diesel Particulate Filter (DPF) inlet temperature sensor and the Aftertreatment Regeneration Device (ARD) flame detection temperature sensor.
This procedure covers the following codes:
| Diagnostic Trouble Codes for the Active Temperature Sensor Circuit | ||
|---|---|---|
| CDL Code | Description | Notes |
| 3485-3 | Aftertreatment #1 Exhaust Gas Temperature #1 Sensor : Voltage Above Normal | The ECM detects the following conditions: The signal voltage for the ARD flame detection temperature sensor is greater than 4.7 VDC for at least 4 seconds. The ECM has been powered for at least 7 seconds. If equipped, the warning light will come on. The ECM will log the diagnostic code. The engine will be derated. If a regeneration is in progress, the process will be stopped. Future regenerations will be prevented while the code is active. |
| 3485-4 | Aftertreatment #1 Exhaust Gas Temperature #1 Sensor : Voltage Below Normal | The ECM detects the following conditions: The signal voltage for the ARD flame detection temperature sensor is less than 0.3 VDC for at least 4 seconds. The ECM has been powered for at least 7 seconds. If equipped, the warning light will come on. The ECM will log the diagnostic code. The engine will be derated. If a regeneration is in progress, the process will be stopped. Future regenerations will be prevented while the code is active. |
Pull-up Voltage
The ECM continuously outputs a pull-up voltage on the circuit for the sensor signal wire. The ECM uses this pull-up voltage in order to detect an open in the signal circuit. The presence of a voltage that is above a threshold on the signal circuit generates an open circuit diagnostic code XXXX-3 for the sensor.
If the sensor is disconnected, pull-up voltage indicates that the wires from the sensor connector to the ECM are not open or shorted to ground. The absence of pull-up voltage indicates an open in the signal wire or a short to ground. If the voltage at the sensor connector is different from pull-up voltage, the signal wire is shorted to another wire in the harness.
Note: The DPF inlet/ARD flame detection temperature sensor is a single sensor with two temperature probes. One probe is connected to the DPF. The other probe is connected to the ARD. The probes cannot be disconnected from the sensor.
 | |
| Illustration 1 | g02475998 |
Location of the DPF inlet/ARD flame detection temperature sensor. (1) Temperature probe for the ARD flame detection (2) Temperature probe for the DPF inlet (3) DPF inlet/ARD flame detection temperature sensor | |
 | |
| Illustration 2 | g02032456 |
Schematic for the DPF inlet/ARD flame detection temperature sensor | |
 | |
| Illustration 3 | g02176963 |
Pin locations for the DPF inlet temperature sensor/ARD flame detection temperature sensor on the 31-pin connector and the 40-pin connector | |
 | |
| Illustration 4 | g02177603 |
Connector for the DPF inlet/ARD flame detection temperature sensor (1) 5 VDC supply (2) Ground (3) ARD flame detection temperature sensor signal (4) DPF inlet temperature sensor signal | |
 | |
| Illustration 5 | g01981013 |
P2 connector pin locations. (17) DPF inlet temperature sensor signal (33) ARD flame detection temperature sensor signal (45) DPF/ARD 5 VDC supply (55) DPF/ARD ground | |
Test Step 1. Inspect Electrical Connectors And Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect the 31-pin connector, the 40-pin connector, and the connector for the DPF inlet/ARD flame detection temperature sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the temperature sensor.
- Check the screws for the ECM connector for the correct torque of 6 N·m (53 lb in).
- Check the harness for abrasions, for pinch points, and for corrosion.
Expected Result:
All connectors, pins, and sockets are correctly connected. The harness is free of corrosion, of abrasion, and of pinch points.
Results:
- The connectors and wiring appear to be OK - Proceed to Test Step 2.
- There is a fault in the connectors and/or wiring. -
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are correctly installed and ensure that the connectors are correctly connected.If necessary, perform the "Wiggle Test" on the electronic service tool.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 Active Diagnostic Codes
- Connect the electronic service tool to the diagnostic connector.
- Turn the keyswitch to the ON position.
- Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection in a connector.
Expected Result:
One or more of the diagnostic codes that are listed in Table 1 are active or recently logged.
Results:
- OK - One or more of the preceding diagnostic codes are active or recently logged. Proceed to Test Step 3.
- Not OK - None of the preceding diagnostic codes are active or recently logged.
Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" to identify intermittent faults.
STOP
Test Step 3. Check the Supply Voltage at the Sensor Connector
- Turn the keyswitch to the OFF position.
- Disconnect the harness connector from the DPF inlet/ARD flame detection temperature sensor. Refer to 2.
- Turn the keyswitch to the ON position. Do not start the engine.
- Measure the voltage between terminals 1 and 2 on the sensor connector on the CEM harness. The voltage measurement should be 5.0 ± 0.2 VDC.
- Turn the keyswitch to the OFF position.
- Reconnect the sensor.
Results:
- The voltage measurement is 5.0 ± 0.2 VDC - The correct supply voltage is reaching the sensor. Proceed to Test Step 6.
- The voltage measurement is not 5.0 ± 0.2 VDC. - The correct voltage is not reaching the sensor. Proceed to Test Step 4.
Test Step 4. Check the 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. Do not start the engine.
- Measure the voltage between pin 1 and pin 2 on the 40-pin connector on the harness between the engine and the CEM. The voltage measurement should be 5.0 ± 0.2 VDC.
- Turn the keyswitch to the OFF position.
- Reconnect the 40-pin connector.
Results:
- The voltage measurement is 5.0 ± 0.2 VDC - The fault is in the CEM harness between the 40-pin connector and the sensor connector.
Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault.
STOP
- The voltage measurement is not 5.0 ± 0.20 VDC. - The correct voltage is not reaching the 40-pin connector. Proceed to Test Step 5.
Test Step 5. Check the 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. Do not start the engine.
- Measure the voltage between pin 1 and pin 2 on the 31-pin connector on the engine harness. The voltage measurement should be 5.0 ± 0.2 VDC.
- Turn the keyswitch to the OFF position.
- Reconnect the 31-pin connector.
Results:
- The voltage measurement is 5.0 ± 0.2 VDC - The fault is in the harness between the 40-pin connector and the 31-pin connector.
Repair: Repair the faulty power or ground wiring or replace the faulty power or ground wiring between the 40-pin connector and the 31-pin connector. Use the electronic service tool to verify that the repair eliminates the fault.
STOP
- The voltage measurement is not 5.0 ± 0.20 VDC. - The correct voltage is not reaching the 31-pin connector. The fault is between the 31-pin connector and the ECM.
Repair: Repair the faulty power or ground wiring or replace the faulty power or ground wiring between the 31-pin connector and the ECM. Use the electronic service tool to verify that the repair eliminates the fault.
STOP
Test Step 6. Check that the Diagnostic Code is Still Active
- Connect the electronic service tool to the diagnostic connector.
- Turn the keyswitch to the ON position.
- Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Expected Result:
One of the codes that are listed in Table 1 is active or recently logged.
Results:
- A 3485-4 or 2452-4 diagnostic code is active at this time - Proceed to Test Step 7.
- A 3485-3 or 2452-3 diagnostic code is active at this time - Proceed to Test Step 10.
- No diagnostic codes are active - The problem appears to be resolved.
Repair: Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect" to identify intermittent faults.
STOP
Test Step 7. Create an Open Circuit at the Sensor Connector
- Turn the keyswitch to the OFF position.
- Disconnect the connector for the DPF inlet/ARD flame detection temperature sensor from the CEM harness.
- Turn the keyswitch to the ON position. Wait at least 30 seconds for activation of the diagnostic codes.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-3 diagnostic code for the suspect sensor.
- Turn the keyswitch to the OFF position.
- Reconnect the sensor connector.
Results:
- An XXXX-4 diagnostic code was active before disconnecting the sensor. An XXXX-3 diagnostic code became active after the sensor was disconnected - There may be a fault in the sensor.
Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the DPF or the ARD. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor.Use the electronic service tool in order to clear all logged diagnostic codes.
STOP
- The XXXX-4 diagnostic code is still present - Leave the sensor disconnected. Proceed to Test Step 8.
Test Step 8. 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. Wait at least 30 seconds for activation of the diagnostic codes.
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 3485 and 2452 diagnostic codes.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-3 diagnostic code for the suspect sensor.
- Turn the keyswitch to the OFF position.
- Reconnect the 40-pin connector.
Results:
- An XXXX-4 diagnostic code was active before disconnecting the 40-pin connector. An XXXX-3 diagnostic code became active after the 40-pin connector was disconnected - 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
- The XXXX-4 diagnostic code is still present - Leave the sensor disconnected. Proceed to Test Step 9.
Test Step 9. 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. Wait at least 30 seconds for activation of the diagnostic codes.
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 3485 and 2452 diagnostic codes.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-3 diagnostic code for the suspect sensor.
- Turn the keyswitch to the OFF position.
- Reconnect the 31-pin connector.
Results:
- An XXXX-4 diagnostic code was active before disconnecting the 31-pin connector. An XXXX-3 diagnostic code became active after the 31-pin connector was disconnected. - 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
- The XXXX-4 diagnostic code is still present - Leave the sensor disconnected. Proceed to Test Step 13.
Test Step 10. Create a Short Circuit at the Sensor Connector
- Turn the keyswitch to the OFF position.
- Disconnect the connector for the DPF inlet/ARD flame detection temperature sensor.
- Fabricate a jumper wire that is 150 mm (6 inch) long.
- For a 3485-3 diagnostic code, use the jumper to connect terminal 2 to terminal 3 on the sensor connector.
For a 2452-3 diagnostic code, use the jumper to connect terminal 2 to terminal 4 on the sensor connector.
- Turn the keyswitch to the ON position. Do not start the engine.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-4 diagnostic code for the suspect sensor.
- Remove the jumper. Reconnect the sensor.
Results:
- An XXXX-3 diagnostic code was active before installing the jumper. An XXXX-4 diagnostic code became active with the jumper installed. - There may be a fault in the sensor.
Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the DPF or the ARD. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor.Use the electronic service tool in order to clear all logged diagnostic codes.
STOP
- The XXXX-3 diagnostic code is still present - Proceed to Test Step 11.
Test Step 11. 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.
- For a 3485-3 diagnostic code, use the jumper to connect socket 2 to socket 5 on the 40-pin connector on the harness.
For a 2452-3 diagnostic code, use the jumper to connect socket 2 to socket 6 on the 40-pin connector on the harness.
- Turn the keyswitch to the ON position. Do not start the engine.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-4 diagnostic code for the suspect sensor.
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 3485 and 2452 diagnostic codes.
- Remove the jumper. Reconnect the 40-pin connector.
Results:
- An XXXX-3 diagnostic code was active before installing the jumper. An XXXX-4 diagnostic code became active with the jumper installed. - The fault is in the CEM harness between the sensor connector and the 40-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 XXXX-3 diagnostic code is still present - Proceed to Test Step 12.
Test Step 12. 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.
- For a 3485-3 diagnostic code, use the jumper to connect socket 2 to socket 5 on the 31-pin connector on the engine harness.
For a 2452-3 diagnostic code, use the jumper to connect socket 2 to socket 6 on the 31-pin connector on the engine harness.
- Turn the keyswitch to the ON position. Do not start the engine.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-4 diagnostic code for the suspect sensor.
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 3485 and 2452 diagnostic codes.
- Remove the jumper. Reconnect the 31-pin connector.
Results:
- An XXXX-3 diagnostic code was active before installing the jumper. An XXXX-4 diagnostic code became active with the jumper installed. - 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
- The XXXX-3 diagnostic code is still present. - Proceed to Test Step 13.
Test Step 13. Bypass the Signal Wire in the Engine Harness
- Turn the keyswitch to the OFF position.
- Disconnect the P2 connector.
- Inspect the P2/J2 connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".
- For a 3485 diagnostic code, remove the wire from P2:33.
For a 2452 diagnostic code, remove the wire from P2:17.
- Disconnect the 31-pin connector.
- For a 3485 diagnostic code, remove the wire from socket 5 on the 31-pin connector on the engine harness.
For a 2452 diagnostic code, remove the wire from socket 6 on the 31-pin connector on the engine harness.
- Fabricate a jumper wire that is long enough to reach from the ECM to the 31-pin connector.
- For a 3485 diagnostic code, insert one end of the jumper wire into P2:33. Insert the other end of the jumper wire into socket 5 on the 31-pin connector on the engine harness.
For a 2452 diagnostic code, insert one end of the jumper wire into P2:17. Insert the other end of the jumper wire into socket 6 on the 31-pin connector on the engine harness.
- Reconnect the P2 connector. Reconnect the 31-pin connector.
- Turn the keyswitch to the ON position. Do not start the engine.
- Access the "Active Diagnostic Codes" screen on the electronic service tool and check for active diagnostic codes for the suspect sensor.
Results:
- OK - There are no active 3485 or 2452 diagnostic codes at this time. The fault is in the engine harness.
Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault.
STOP
- Not OK - There is still an active 3485 or 2452 diagnostic code.
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 Cat 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".
- Turn the keyswitch to the ON position. Use the electronic service tool to verify that the repair eliminates the fault.
- If the fault is eliminated with the replacement ECM, reconnect the suspect ECM. If the fault returns with the suspect ECM, replace the ECM.
- If the fault is still present with the replacement ECM, do not use the replacement ECM. Contact the Technical Communicator at a Cat dealer.
STOP