C18 Industrial Engine Caterpillar

Use this procedure to troubleshoot a suspected problem with the soot sensing system. Use this procedure if a diagnostic code in Table 1 is active or easily repeated.

Note: Refer to Troubleshooting, "Cat ET Service Features" for information about service features.

Table 1

Diagnostic Trouble Codes
CDL Code	Code Description	Comments
3397-3	DPF #1 Soot Loading Sensor : Voltage Above Normal	The Electronic Control Module (ECM) detects voltage that is not in the acceptable range. The code is logged.
3397-4	DPF #1 Soot Loading Sensor : Voltage Below Normal	The ECM detects voltage that is not in the acceptable range. The code is logged.
3397-19	DPF #1 Soot Loading Sensor : Data Drifted Low	There is an electrical problem with soot sensing system. The code is logged.
3397-21	DPF #1 Soot Loading Sensor : Data Error	There is an electrical problem with soot sensing system. The code is logged.

Table 2

Associated Diagnostic Trouble Codes
168	2,3 or 4

Table 3

Troubleshooting Test Steps	Values	Results
1. Check for Active Diagnostic Codes A. Establish communication between the Cat ET and the engine ECM. B. Turn the keyswitch to the ON position. C. Download the engine "Warranty Report" before performing any troubleshooting or clearing diagnostic trouble codes.	Codes	Result: An associated code is active. Troubleshoot the associated code. Verify that the problem is resolved. Result: A 3397-3 diagnostic code is active. The voltage to the soot sensing system is above 32 VDC. There is a problem with the harness and/or the connectors for the soot sensing module. Repair the harness and/or connectors or replace the harness and/or connectors. Refer to Illustration 1 for additional information.. Verify that the original problem is resolved. Result: A 3397-4 diagnostic code is active. The voltage to the soot sensing system is below 9 VDC. There is a problem with the harness and/or the connectors for the soot sensing module. Repair the harness and/or connectors or replace the harness and/or connectors. Refer to Illustration 1 for additional information. Verify that the original problem is resolved. Result: A 3397-21 diagnostic code is active. There is an electrical and/or mechanical problem with the soot sensing system. Proceed to Test Step 2

Illustration 1	g02161091
Soot sensing module and connector

Illustration 2	g02177161
Connector torque point (1) Torque point

Table 4

Troubleshooting Test Steps	Values	Results
2. Check the Coaxial Cable A. Inspect the coaxial cable. Verify that every connection for the coaxial cable in the soot sensing system is securely connected. Also, check each connection for dirt and water. The dirt and water must be cleaned from the connector each time a connection is made. B. Torque every connector for the coaxial cable to 1.2 N·m (10.6 lb in) / −0.2 N·m (1.8 lb in).	Codes	Result: The coaxial cable is OK. Proceed to Test Step 3. Result: The coaxial cable is not OK. Make the necessary repairs. Reset all active codes and clear all logged codes. Verify that the problem is resolved.

Illustration 3	g02151941
366-7782 Attenuator

Table 5

Troubleshooting Test Steps	Values	Results
3. Perform the "DPF Soot Loading Sensor Functional Test" A. Disconnect the coaxial cable from the antennas. B. Connect the ends of the coaxial cable to the 366-7782 Attenuator. Refer to Illustration 3. C. Perform the "DPF Soot Loading Sensor Functional Test" on Cat ET by selecting the following menus: 1. Diagnostics 2. Diagnostic Tests 3. DPF Soot Loading Sensor Functional Test	Codes	Result: The service test is successful. Remove the antennas from the DPF in order to inspect for bent or broken probes. Replace any faulty antennas and reinstall the good antenna (if applicable). Torque the connector's for the coaxial cable to 1.2 N·m (10.6 lb in) / −0.2 N·m (1.8 lb in). Verify that the problem is resolved. Result: The service test is not successful. Replace the soot sensing module. Torque the connectors for the coaxial cable to 1.2 N·m (10.6 lb in) / −0.2 N·m (1.8 lb in). Verify that the problem is resolved.