3512C Engines for 785C Off-Highway Trucks with Dynamic Gas Blending Caterpillar

Sensor Signal (PWM) - Test

Usage:

3512 8BR

Use this procedure to troubleshoot a problem with a turbocharger turbine inlet temperature sensor. 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
1180-3 Engine Turbocharger 1 Turbine Inlet Temperature : Voltage Above Normal	3908-3 Engine Turbocharger #1 Turbine Intake Temperature Sensor : Voltage Above Normal	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.
1180-4 Engine Turbocharger 1 Turbine Inlet Temperature : Voltage Below Normal	3908-4 Engine Turbocharger #1 Turbine Intake Temperature Sensor : Voltage Below Normal	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.
1180-8 Engine Turbocharger 1 Turbine Inlet Temperature : Abnormal Frequency, Pulse Width, or Period	3908-8 Engine Turbocharger #1 Turbine Intake Temperature Sensor : Abnormal Frequency, Pulse Width, or Period	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.
1181-3 Engine Turbocharger 2 Turbine Inlet Temperature : Voltage Above Normal	3909-3 Engine Turbocharger #2 Turbine Intake Temperature Sensor : Voltage Above Normal	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.
1181-4 Engine Turbocharger 2 Turbine Inlet Temperature : Voltage Below Normal	3909-4 Engine Turbocharger #2 Turbine Intake Temperature Sensor : Voltage Below Normal	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.
1181-8 Engine Turbocharger 2 Turbine Inlet Temperature : Abnormal Frequency, Pulse Width, or Period	3909-8 Engine Turbocharger #2 Turbine Intake Temperature Sensor : Abnormal Frequency, Pulse Width, or Period	If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used. The code is logged.

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Illustration 1	g06309261

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Determine if a code is active or logged.	Codes	Result: A -3 code is active or logged. Proceed to Test Step 2. Result: A -4 code is active or logged. Proceed to Test Step 3. Result: A -8 code is active or logged. Proceed to Test Step 5.
2. Create a Short at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -3 code. C. Install the jumper wire between the following terminals at the sensor connector: - Pin 2 (sensor return) and Pin 3 (sensor signal) D. Connect Cat ET. E. Use Cat ET to monitor the following: - -4 code F. Turn the keyswitch to the OFF position.	Create a Short	Result: A -4 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem. Result: A -4 code did not become active. Proceed to Test Step 4.
3. Create an Open at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -4 code. C. Connect Cat ET. D. Use Cat ET to monitor the following: - -3 code E. Turn the keyswitch to the OFF position.	Create an Open	Result: A -3 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem. Result: A -3 code did not become active. Proceed to Test Step 4.
4. Check the 8 VDC Supply Voltage at the Sensor Connector A. Turn the keyswitch to the ON position. B. Measure the voltage at the following pin locations of the affected sensor connector: - Pin 1 and Pin 2 C. Reconnect the sensor.	Supply Voltage	Result: The supply voltage is approximately 8.0 ± 0.2 VDC Proceed to Test Step 8. Result: The supply voltage is not approximately 8.0 ± 0.2 VDC. Repair: There is a short in the wiring harness to the battery. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 5.
5. Check the PWM Circuit for an Open A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -8 code. C. Disconnect the J2 connector at the ECM. D. Measure the resistance between the following locations for the sensor: - Pin 3 (sensor connector) and the appropriate PWM signal wire on the ECM connector	Open Circuit	Result: Less than 10 ohms of resistance between the sensor connector and the ECM connector. Proceed to Test Step 6. Result: More than 10 ohms of resistance between the sensor connector and the ECM connector. Repair: There is an open circuit in the wiring harness. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 6.
6. Check the PWM Circuit for a Short Circuit A. Turn the keyswitch to the OFF position B. Disconnect the sensor with the active -8 code. C. Disconnect the J2 connector at the ECM. D. Measure the resistance between the following locations for the sensor: - Pin 3 (sensor connector) and Engine ground	Short Circuit	Result: There were more than 100 K ohms of resistance between pin 3 and engine ground. Proceed to Test Step 7. Result: There were less than 100 K ohms of resistance between pin 3 and engine ground. Repair: There is a short circuit in the wiring harness. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 7.
7. Check the PWM Circuit for a Pin to Pin Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -8 code. C. Disconnect the J2 connector at the ECM. D. Measure the resistance between the following locations for the sensor: - Pin 3 (sensor connector) and all ECM connector pins	Short Circuit	Result: There were more than 100 K ohms of resistance between the signal pin at the ECM and all other pins in the ECM connector. Proceed to Test Step 8. Result: There were less than 100 K ohms of resistance between the signal pin at the ECM and all other pins in the ECM connector. Repair: There is a short circuit in the wiring harness. Repair or replace the wiring harness If the problem is not resolved, proceed to Test Step 8.
8. Perform the Wiggle Test Carefully following this procedure is the best way to identify the root cause of an intermittent problem. A. Turn the keyswitch to the ON position. B. Connect Cat ET. C. Use CAT ET to perform the following test: - "Wiggle Test" D. Slowly wiggle the wiring and the connectors between the P2 connector and the sensor. Pay particular attention to the wiring near each connector. Be sure to wiggle all the wiring. As you wiggle the wiring look for the following problems: - Loose connectors or damaged connectors - Moisture on the connectors or the wiring - Damaged that is caused by excessive heat - Damage that is caused by chafing - Improper routing of wiring - Damaged insulation	Test	Result: The wiring failed the Wiggle Test. Repair: There is a problem with the wiring harness. Repair or replace the wiring harness. Verify that the repair eliminated the problem. Result: The wiring passed the Wiggle Test. The problem may be intermittent. Inspect the wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. Repair: Perform the following procedure: 1. Turn the keyswitch to the OFF position. 2. Disconnect the connectors. Carefully inspect the terminals for proper installation. 3. Insert a pin into each socket. Verify that each socket grips the pin firmly. Repair any problems. 4. Connect all connectors. Verify that the repair eliminated the problem.

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).