C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

793F D3T

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

Show/hide table

Table 1
J1939 Code and Description	CDL Code and Description	Comments
95-2 Engine Fuel Filter Differential Pressure : Erratic, Intermittent, or Incorrect	95-2 Fuel Filter Differential Pressure Sensor : Erratic, Intermittent, or Incorrect	This code indicates that the fuel pressure sensor connections are swapped. Swap the connectors for the unfiltered and filtered fuel pressure sensors.
99-2 Engine Oil Filter Differential Pressure : Erratic, Intermittent, or Incorrect	99-2 Engine Oil Filter Differential Pressure Sensor : Erratic, Intermittent, or Incorrect	This code indicates that the oil pressure sensor connections are swapped. Swap the connectors for the oil pressure sensor before the secondary filter and the oil pressure sensor after the secondary filter.
100-3 Engine Oil Pressure : Voltage Above Normal	100-3 Engine Oil Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
100-4 Engine Oil Pressure : Voltage Below Normal	100-4 Engine Oil Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
101-3 Engine Crankcase Pressure : Voltage Above Normal	101-3 Crankcase Air Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
101-4 Engine Crankcase Pressure : Voltage Below Normal	101-4 Crankcase Air Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
108–3 Barometric Pressure : Voltage Above Normal	3528–3 Barometric Pressure : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
108–4 Barometric Pressure : Voltage Below Normal	3528–4 Barometric Pressure : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
109-3 Engine Coolant Pressure : Voltage Above Normal	2302-3 Engine Coolant Pump Outlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
109-4 Engine Coolant Pressure : Voltage Below Normal	2302-4 Engine Coolant Pump Outlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
157–3 Engine Injector Metering Rail #1 Pressure : Voltage Above Normal	1797–3 Fuel Rail Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
157–4 Engine Injector Metering Rail #1 Pressure : Voltage Below Normal	1797–4 Fuel Rail Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1176-3 Engine Turbocharger 1 Compressor Inlet Pressure : Voltage Above Normal	2738-3 Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1176-4 Engine Turbocharger 1 Compressor Inlet Pressure : Voltage Below Normal	2738-4 Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1177-3 Engine Turbocharger 2 Compressor Inlet Pressure : Voltage Above Normal	2739-3 Turbocharger #2 Compressor Inlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1177-4 Engine Turbocharger 2 Compressor Inlet Pressure : Voltage Below Normal	2739-4 Turbocharger #2 Compressor Inlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1178-3 Engine Turbocharger #3 Compressor Inlet Pressure : Voltage Above Normal	2740-3 Turbocharger #3 Compressor Inlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1178-4 Engine Turbocharger #3 Compressor Inlet Pressure : Voltage Below Normal	2740-4 Turbocharger #3 Compressor Inlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1179-3 Engine Turbocharger #4 Compressor Inlet Pressure : Voltage Above Normal	2741-3 Turbocharger #4 Compressor Inlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1179-4 Engine Turbocharger #4 Compressor Inlet Pressure : Voltage Below Normal	2741-4 Turbocharger #4 Compressor Inlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1208-3 Engine Pre-filter Oil Pressure : Voltage Above Normal	542-3 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1208-4 Engine Pre-filter Oil Pressure : Voltage Below Normal	542-4 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1381–3 Engine Fuel Supply Pump Inlet Pressure : Voltage Above Normal	2247–3 Fuel Transfer Pump Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
1381–4 Engine Fuel Supply Pump Inlet Pressure : Voltage Below Normal	2247–4 Fuel Transfer Pump Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
3563-3 Engine Intake Manifold #1 Absolute Pressure : Voltage Above Normal	1785-3 Intake Manifold Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
3563-4 Engine Intake Manifold #1 Absolute Pressure : Voltage Below Normal	1785-4 Intake Manifold Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4360-3 Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Above Normal	3105-3 Aftertreatment #1 SCR Catalyst Intake Gas Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4360-4 Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Below Normal	3105-4 Aftertreatment #1 SCR Catalyst Intake Gas Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4413–4 Aftertreatment #2 SCR Catalyst Intake Gas Temperature : Voltage Below Normal	3106–4 Aftertreatment #2 SCR Catalyst Intake Gas Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5417–3 Fuel Filter (suction side) Intake Pressure Sensor : Voltage Above Normal	4594–3 Electric Fuel Transfer Pump Outlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5417–4 Fuel Filter (suction side) Intake Pressure Sensor : Voltage Below Normal	4594–4 Electric Fuel Transfer Pump Outlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5422–3 Engine Intake Manifold #2 Absolute Pressure : Voltage Above Normal	3031–3 Intake Manifold #2 Pressure Sensor " Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5422–4 Engine Intake Manifold #2 Absolute Pressure : Voltage Below Normal	3031–4 Intake Manifold #2 Pressure Sensor " Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5578–3 Engine Fuel Delivery Pressure : Voltage Above Normal	289–3 Fuel Pressure Sensor - Before Fuel Filter : Voltage Above Normal	The Electronic Control Module (ECM) detects signal voltage that is not in the acceptable range. The code is logged.
5578–4 Engine Fuel Delivery Pressure : Voltage Below Normal	289–4 Fuel Pressure Sensor - Before Fuel Filter : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5579–3 Engine Filtered Fuel Delivery Absolute Pressure : Voltage Above Normal	460–3 Fuel Pressure Sensor - After Fuel Filter : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5579–4 Engine Filtered Fuel Delivery Absolute Pressure : Voltage Below Normal	460–4 Fuel Pressure Sensor - After Fuel Filter : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6797-3 Aftertreatment #1 SCR Intake Absolute Pressure : Voltage Above Normal	4054-3 Aftertreatment #1 SCR Catalyst Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6797-4 Aftertreatment #1 SCR Intake Absolute Pressure : Voltage Below Normal	4054-4 Aftertreatment #1 SCR Catalyst Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6798-3 Aftertreatment #2 SCR Intake Absolute Pressure : Voltage Above Normal	4055-3 Aftertreatment #2 SCR Catalyst Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6798-4 Aftertreatment #2 SCR Intake Absolute Pressure : Voltage Below Normal	4055-4 Aftertreatment #2 SCR Catalyst Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.

The supply voltage is routed to terminal 1 of each sensor connector. The sensor return is routed to terminal 2 of each sensor connector. The sensor signal is routed to terminal 3 of each sensor connector. The Electronic Control Module (ECM) provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.

Diagnostics on the Cat^® Electronic Technician (ET)

Wiggle Test - The Wiggle Test allows you to monitor the status of the signals from the sensors.

For additional information regarding the Wiggle Test, refer to the documentation that accompanies the Cat ET software.

Show/hide table




Illustration 1	g06104265
ECM schematic

Show/hide table




Illustration 2	g06104561
Selective Catalyst Reduction (SCR) Controller

Show/hide table

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. Proceed to Test Step 2. Result: A -4 code is active. Proceed to Test Step 3.
2. Create a Short at the Sensor Connector A. Turn the keyswitch to OFF. B. Disconnect the sensor with the active -3 code. C. Install the jumper wire between the following terminals at the sensor connector: - Terminal 3 (signal) and Terminal 2 (sensor return) D. Connect Cat ET. E. Use Cat ET to monitor the following: - -4 code F. Turn the keyswitch to OFF.	Create a Short	Result: A -4 code did not become active. Proceed to Test Step 4. Result: A -4 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem.
3. Create an Open at the Sensor Connector A. Turn the keyswitch to OFF. 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 OFF.	Create an Open	Result: A -3 code did not become active. Proceed to Test Step 4. Result: A -3 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem.
4. Check the 5 VDC Supply Voltage at the Sensor Connector A. Turn the keyswitch to ON. B. Measure the voltage at the sensor connector between the following pins: - Pin 1 and Pin 2 C. Reconnect the sensor.	5.0 ± 0.2 VDC	Result: The supply voltage is approximately 5.0 ± 0.2 VDC. Proceed to Test Step 5. Result: The supply voltage is not approximately 5.0 ± 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. Perform the Wiggle Test Carefully following this procedure is the best way to identify the root cause of an intermittent problem. A. Connect Cat ET. B. Use CAT ET to perform the following test: - "Wiggle Test" C. 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 these 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. Repair: The problem may be intermittent. Inspect the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. If the wiring looks OK, perform the following procedure: 1. Turn the keyswitch to the OFF position. 2. Disconnect the connectors. Carefully inspect the terminals for proper installation. Make sure that each terminal is clean and dry. 3. Insert a pin into each socket. Verify that each socket grips the pin firmly. Repair any problems. 4. Connect all connectors. 5. 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).