C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

Sensor (Data Link Type) - Test

Usage:

793F D3T

Use this procedure to troubleshoot a problem with the CAN data link. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
3216-11 Aftertreatment #1 Intake NOx : Other Failure Mode	3655-11 Aftertreatment #1 Intake NOx Level Sensor : Other Failure Mode	The #1 intake NOx sensor heater cannot generate enough heat or the power supply is intermittent.
3216-12 Aftertreatment #1 Intake NOx : Failure	3655-12 Aftertreatment #1 Intake NOx Level Sensor : Failure	A failed #1 intake NOx sensor has been detected.
3226-11 Aftertreatment #1 Outlet NOx : Other Failure Mode	3609-11 Aftertreatment #1 Outlet #1 NOx Level Sensor : Other Failure Mode	The #1 outlet NOx sensor heater cannot generate enough heat or the power supply is intermittent.
3226-12 Aftertreatment #1 Outlet NOx : Failure	3609-12 Aftertreatment #1 Outlet #1 NOx Level Sensor : Failure	A failed #1 outlet NOx sensor has been detected.
3255–11 Aftertreatment #2 Intake NOx : Other Failure Mode	3656–11 Aftertreatment #2 Intake NOx Level Sensor : Other Failure Mode	The #2 outlet NOx sensor heater cannot generate enough heat or the power supply is intermittent.
3255–12 Aftertreatment #2 Intake NOx : Failure	3656–12 Aftertreatment #2 Intake NOx Level Sensor : Failure	A failed #2 outlet NOx sensor has been detected.
3265–11 Aftertreatment #2 Outlet NOx : Other Failure Mode	5141–11 Aftertreatment #1 Outlet #2 NOx Level Sensor : Other Failure Mode	The #2 outlet NOx sensor heater cannot generate enough heat or the power supply is intermittent.
3265–12 Aftertreatment #2 Outlet NOx : Failure	5141–12 Aftertreatment #1 Outlet #2 NOx Level Sensor : Failure	A failed #2 outlet NOx sensor has been detected.
3360–12 Aftertreatment #1 DEF Controller #1 : Failure	3820–12 Aftertreatment #1 DEF Controller : Failure	The #1 DCU has been flashed or a failed #1 DCU has been detected.
4450–12 Aftertreatment #2 Diesel Exhaust Fluid Controller : Failure	4577–12 Aftertreatment #2 DEF Controller #1 : Failure	The #2 intake NOx sensor heater cannot generate enough heat or the power supply is intermittent.
7538-12 Aftertreatment #1 Diesel Exhaust Fluid Controller #2 : Failure	4797-12 Aftertreatment #1 DEF Controller #2 : Failure	The #2 DCU has been flashed or a failed #2 DCU has been detected.
7539–12 Aftertreatment #2 DEF Controller #2 : Failure	4798–12 Aftertreatment #2 DEF Controller #2 : Failure	The #2 intake NOx sensor heater cannot generate enough heat or the power supply is intermittent.

Note: Turn the keyswitch to the OFF position before connecting or disconnecting these components.

If the Cat^® Electronic Technician (ET) will not communicate with the Electronic Control Module (ECM), refer to Troubleshooting, "Electronic Service Tool Does Not Communicate" before you begin this procedure. The procedure verifies that electrical power is being supplied to the ECM and to the service tool connector.

The data links are used to communicate information between the engine ECM and other control modules that are a part of the application. Cat ET also communicates with the ECM via the data links.

The service tool connector contains connections for electrical power and for the data links.

When the keyswitch is in the OFF position, Cat ET may communicate with the ECM. However, the communications may be disrupted and the communications may require frequent reconnection. To avoid this problem, place the keyswitch in the ON position when Cat ET is being used.

Cat ET may display the following error message:

"The version of the ECM is not recognized and the integrity of the changed parameters and displayed data is not guaranteed."

This message indicates that one of the following conditions exist:

The flash file in the ECM is newer than the version of Cat ET.
The latest version of Cat ET has not been installed.

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Illustration 1	g06190521
The NOx sensors are on the Clean Emissions Module (CEM). (1) Aftertreatment #1 Inlet NOx sensor (2) Aftertreatment #2 Inlet NOx sensor (3) Aftertreatment #2 Outlet NOx sensor (4) Aftertreatment #1 Outlet NOx sensor

Probable Causes

Codes
Electrical connectors and wiring
Battery voltage
DCU

Recommended Actions

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® ET to the service tool connector. B. Determine if a code is active or logged.	Codes	Result: A -11 code is active or logged. Proceed to Test Step 2. Result: A 3360-12, 3820-12, 4450-12, 4577-12, 7538-12, 4794-12, 7539-12, or 4798-12 code is active or logged. Proceed to Test Step 4. Result: A -12 code listed above is active or logged. Repair: Replace the failed NOx sensor. Refer to Special Instruction, REHS8151 for special handling instructions. Proceed to Test Step 5.
2. Inspect the Electrical Connectors and the Wiring A. Turn the keyswitch to OFF. B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information. C. Perform a 45 N (10 lb) pull test on the connector wires. D. Check the harness for abrasions and pinch points.	Connectors and Wiring	Result: The connectors and wiring appear to be OK. Proceed to Test Step 3. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Note: The Diesel Exhaust Fluid Control Unit (DCU) connector is not serviceable. If the problem is not resolved, proceed to Test Step 3.
3. Check the Voltage to the Affected Sensor A. Disconnect the affected sensor from the wiring harness. B. Turn the keyswitch to ON. C. Measure the voltage on the wiring harness connector between the following: - +Battery (supply) and -Battery (return)	Battery Voltage	Result: The measured voltage is equal to battery voltage. Repair: Replace the failed NOx sensor. Refer to Special Instruction, REHS8151 for special handling instructions. Proceed to Test Step 5. Result: The measured voltage is not equal to battery voltage. Repair: There is a problem with an intermittent battery supply. Check the power supply to the affected sensor. If the problem is not resolved, proceed to Test Step 5.
4. Perform the "DEF Dosing Control Module Reset" A. Connect Cat ET. B. Select the "Selective Catalyst Reduction System". C. Use Cat ET to perform the following diagnostic test: - DEF Dosing Control Module Key Switch Line Test	Reset	Result: A 3360-12, 3820-12, 4450-12, 4577-12, 7538-12, 4794-12, 7539-12, or 4798-12 code is active or logged. Return to service. Result: A 3360-12, 3820-12, 4450-12, 4577-12, 7538-12, 4794-12, 7539-12, or 4798-12 code is not active or logged. Repair: Replace the DCU. Proceed to Test Step 5.
5. Perform the "Aftertreatment System Functional Test" A. Connect Cat ET. B. Select the "Selective Catalyst Reduction System". C. Use Cat ET to perform the following diagnostic test: - "Aftertreatment System Functional Test"	Test	Result: The test was successful. Return to service.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).