C7.1 Engines and Generator Sets Caterpillar

Soot Sensor - Test

Usage:

C7.1 770

Use this procedure to troubleshoot a fault with the soot sensor. Also, use this procedure if the diagnostic code in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table for Soot Sensor
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
4783-3	3397-3	DPF #1 Mean Soot Signal : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage for the soot sensor is greater than 32 VDC for 60 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The EBPR may close as a precaution.
4783-4	3397-4	DPF #1 Mean Soot Signal : Voltage Below Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage for the soot sensor is less than 9 VDC for 60 seconds. The warning lamp will come on. The ECM will log the diagnostic code. The EBPR may close as a precaution.
4783-9	3397-9	DPF #1 Mean Soot Signal : Abnormal Update Rate	The ECM detects the following conditions: There is no signal from the soot sensor. The warning lamp will come on and the ECM will log the diagnostic code. The ECM will use the last good value for the signal.
4783-12	3397-12	DPF #1 Mean Soot Signal : Failure	The ECM detects the following conditions: The soot sensor has failed. The warning lamp will come on and the ECM will log the diagnostic code.
4783-13	3397-13	DPF #1 Mean Soot Signal : Calibration Required	The ECM detects the following conditions: The soot sensor has not been calibrated by the manufacturer. The warning lamp will come on and the ECM will log the diagnostic code.
4783-21	3397-21	DPF #1 Mean Soot Signal : Data Drifted Low	The ECM detects the following conditions: The soot sensor has not received a valid signal from the soot antenna for at least 60 seconds. The warning lamp will come on and the ECM will log the diagnostic code.

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Table 2
Required Tools
Tool	Part Number	Part Description	Qty
A	366-7782	Attenuator	1

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

The ECM has been powered for at least 60 seconds.
There are no active 168 codes.

The following background information is related to this procedure:

The soot sensor is powered from the switched battery voltage. A signal is sent by the soot sensor to one soot antenna. The signal that is received by the other antenna is sent back to the soot sensor. The signal is attenuated by the soot in the Diesel Particulate Filter (DPF). The soot sensor calculates the soot load in the DPF by measuring the attenuation of the signal.

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Illustration 1	g06156441
Schematic diagram for the soot sensor circuit

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Illustration 2	g02458558
View of the pin locations on the P1 connector for the soot sensor (29) CAN B + (21) CAN B -

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

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Table 3
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 speed/timing 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 screw for the ECM connector for the correct torque of 6 N·m (53 lb in). E. Check the ground connection on the ECM for abrasions and pinch points. F. Check the harness for abrasion and pinch points from the suspect sensor to the ECM. G. Check that the suspect sensor is installed correctly. Check that the suspect sensor is fully seated into the engine.	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. Repair: There may be an intermittent fault. Use the electronic service tool to perform a Wiggle Test. If no fault is identified If no fault is identified, 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. Download the "Product Summary Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. D. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes. Look for an active or logged code. E. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: Diagnostic code 4783-3 (3397-3) is active. Proceed to Test Step 3. Result: Diagnostic code 4783-4 (3397-4) is active. Proceed to Test Step 4. Result: Diagnostic code 4783-9 (3397-9) is active. Proceed to Test Step 5. Result: Diagnostic code 4783-12 (3397-12) is active. Proceed to Test Step 6. Result: Diagnostic code 4783-13 (3397-13) is active. Proceed to Test Step 7. Result: Diagnostic code 4783-21 (3397-21) is active. Proceed to Test Step 8.
3. Check for a High Voltage at the Soot Sensor A. Turn the keyswitch to the ON position. B. Measure the voltage across pins 1 and 2 on the soot sensor connector. C. Turn the keyswitch to the OFF position.	Less than 32 VDC	Result: The supply voltage is within the acceptable range for the soot sensor. Return the unit to service Result: The supply voltage is above the acceptable range for the soot sensor. Repair: Investigate the cause of the high voltage. Refer to Systems Operation, Testing and Adjusting, "Charging System - Inspect".
4. Check for a Low Voltage at the Soot Sensor A. Turn the keyswitch to the ON position. B. Measure the voltage across pins 1 and 2 on the soot sensor. C. Turn the keyswitch to the OFF position.	More than 9 VDC	Result: The supply voltage is within the acceptable range for the soot sensor. Return the unit to service. Result: The supply voltage is below the acceptable range for the soot sensor. Repair: Make sure that any in-line fuses are intact. Replace any blown fuses. Check that the supply voltage is adequate. Refer to Systems Operation, Testing and Adjusting, "Charging System - Inspect". If the supply voltage is satisfactory, inspect the wiring and the connectors. Refer to Troubleshooting, "Electrical Power Supply - Test".
5. Diagnostic Code 4783-9 (3397-9) is Active Note: This fault can be caused by a complete loss of voltage to the soot sensor module. The fault can also be caused by a CAN data link fault between the soot sensor module and the ECM. A. Check the fuse for the power supply to the soot sensor module. Inspect all electrical connections associated with the power supply to the soot sensor module. Refer to the Electrical Schematic for the application and refer to Troubleshooting, "Electrical Connectors - Inspect". B. Test the CAN B data link between the soot sensor and the engine ECM. Refer to Troubleshooting, "Can Data Link Circuit - Test".	Data signal	Result: The power supply to the soot sensor module is faulty. Repair: Replace any blown fuses. Make any necessary repairs. Refer to the Electrical Schematic for the application and refer to Troubleshooting, "Electrical Connectors - Inspect". Result: The data link is faulty. Repair: Make any necessary repairs. Refer to Troubleshooting, "Can Data Link Circuit - Test".
6. Diagnostic Code 4783-12 (3397-12) is Active A. If diagnostic code 4783-12 (3397-12) is active, the soot sensor has a fault.	Faulty sensor	Result: Diagnostic code 4783-12 (3397-12) is active. There is a fault in the soot sensor. Repair: Replace the soot sensor.
7. Diagnostic Code 4783-13 (3397-13) is Active Note: If diagnostic code 4783-13 (3397-13) is active, the soot sensor requires a factory calibration.	Sensor calibration	Result: Diagnostic code 4783-13 (3397-13) is active. Repair: The soot sensor requires a factory calibration. Replace the soot sensor.
8. Check the Soot Antennas Note: If diagnostic code 4783-21 (3397-21) is active, the soot sensor is not receiving a signal from the soot antennas. Note: If any corrective action is performed, allow a period of 60 seconds for the diagnostic code to disappear. A. Inspect the coaxial cable. Check each connection for dirt or water ingress. All connectors must be clean and dry before connections are made. Verify that all the connectors are securely connected. B. Torque all coaxial connectors to 1.2 N·m (10.6 lb in). C. After 60 seconds, check for diagnostic code 4783-21 (3397-21). D. If diagnostic code 4783-21 or 3397-21 is still active, continue with this procedure. E. Disconnect the coaxial cables from the antennas. F. Connect the ends of the coaxial cables to Tooling (A). G. Perform the "DPF Soot Loading Sensor Functional Test" on the electronic service tool by selecting the following menus: · "Diagnostics" · "Diagnostic Tests" · "DPF Soot Loading Sensor Functional Test" H. Disconnect the coaxial cables from the attenuator.	Faulty soot antenna	Result: The "DPF Soot Loading Sensor Functional Test" is successful. The fault is in a soot antenna. Repair: Remove the two soot antennas from the DPF. Refer to Disassembly and Assembly, "Soot Antenna - Remove and Install". Inspect the soot antennas for damaged or bent probes. Replace a damaged antenna. If no damage is found, replace both antennas. Install the two soot antennas. Refer to Disassembly and Assembly, "Soot Antenna - Remove and Install". Ensure that the antenna connectors are tightened to a torque of 1.2 N·m (10.6 lb in). After 60 seconds, confirm that diagnostic code 4783-21 (3397-21) is no longer active. Result: The "DPF Soot Loading Sensor Functional Test" is not successful. The fault is in the soot sensor or a coaxial cable. Repair: Replace the soot sensor. Ensure that the antenna connectors are tightened to a torque of 1.2 N·m (10.6 lb in). Repeat the "DPF Soot Loading Sensor Functional Test" and confirm that the test is successful. If the fault has not been eliminated, contact the Dealer Solutions Network (DSN).