C175 Petroleum Engine Caterpillar

Sensor Supply - Test

Usage:

Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor supply. 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
100-21 Engine Oil Pressure : Data Drifted Low	100-21 Engine Oil Pressure Sensor : Data Drifted Low	The code is logged.
101-21 Engine Crankcase Pressure : Data Drifted Low	N/A	The code is logged.
108-21 Barometric Pressure : Data Drifted Low	3528-21 Barometric Pressure Sensor : Data Drifted Low	The code is logged.
678-3 ECU 8 Volt DC Supply : Voltage Above Normal	41-3 8 Volt DC Supply : Voltage Above Normal	The code is logged.
678-4 ECU 8 Volt DC Supply : Voltage Below Normal	41-4 8 Volt DC Supply : Voltage Below Normal	The code is logged.
1208-21 Engine Pre-filter Oil Pressure : Data Drifted Low	542-21 Engine Oil Pressure Sensor - Before Oil Filter : Data Drifted Low	The code is logged.
3509-3 Sensor Supply Voltage 1 : Voltage Above Normal	262-3 5 V Sensor DC Power Supply : Voltage Above Normal	All sensors are set to default values. The code is logged.
3509-4 Sensor Supply Voltage 1 : Voltage Below Normal	262-4 5 V Sensor DC Power Supply : Voltage Below Normal	All sensors are set to default values. The code is logged.
3510-3 or Supply Voltage 2 : Voltage Above Normal	2131-3 5 V Sensor DC Power Supply #2 : Voltage Above Normal	Engine power may be derated. The code is logged.
3510-4 Sensor Supply Voltage 2 : Voltage Below Normal	2131-4 5 V Sensor DC Power Supply #2 : Voltage Below Normal	Engine power may be derated. The code is logged.
3563-21 Engine Intake Manifold #1 Absolute Pressure : Data Drifted Low	1785-21 Intake Manifold Pressure Sensor : Data Drifted Low	The 5 VDC supply to the sensor has been lost. The code is logged.
5578-21 Engine Fuel Delivery Absolute Pressure : Data Drifted Low	289-21 Fuel Pressure Sensor - Before Fuel Filter : Data Drifted Low	The 5 VDC supply to the sensor has been lost. The code is logged.
5580-21 Engine Filtered Fuel Delivery Absolute Pressure : Data Drifted Low	460-21 Fuel Pressure Sensor - After Fuel Filter : Data Drifted Low	The 5 VDC supply to the sensor has been lost. The code is logged.

The Electronic Control Module (ECM) supplies a regulated voltage of 5.0 ± 0.2 VDC to the sensors.

The supply voltage for the sensors is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal 2 of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.

Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If any of the diagnostic codes are active, a sensor may have been damaged. Repair the sensor supply and check for any active sensor diagnostic codes to determine if a sensor has been damaged.

Show/hide table

Table 2
Sensor Supply	Sensor Supply ECM Location
Sensor Supply #1	Sensors on A5:E4 engine ECM J2 connector or A5:E2 aftertreatment controller J2 connector
Sensor Supply #2	Sensors on A5:E4 engine ECM J1 connector

Show/hide table




Illustration 1	g06360484
Schematic for the primary analog sensors that are shown in the right side engine view

Show/hide table




Illustration 2	g06323446
Schematic for the primary analog sensors that are shown in the front engine view

Show/hide table




Illustration 3	g06360516
Schematic for the primary analog sensors that are shown in the top engine view

Show/hide table




Illustration 4	g06323402
Schematic of the PWM sensors for the sensor signal circuit

Show/hide table




Illustration 5	g06321957
Schematic for the secondary analog sensors

Show/hide table




Illustration 6	g06321987
Schematic for the secondary analog sensors

Show/hide table




Illustration 7	g06360518
Schematic for the secondary analog sensors

Show/hide table

Table 3
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 or -4 code is active. Note which ECM is reporting the active code. Proceed to Test Step 2. Result: A -21 code is active. Proceed to Test Step 3.
2. Check for a Failed Sensor A. Connect Cat ET. B. Disconnect a sensor on the affected sensor supply circuit. C. Use Cat ET to monitor following: - Active code changes to logged D. Connect the affected sensor to the wiring harness. E. Repeat Step B through Step D for each sensor on the affected sensor supply.	Sensor	Result: The affected sensor supply active code changed to a logged code when a sensor is unplugged. Repair: Repair or replace the failed sensor. Verify that the repair eliminated the problem. Result: The affected sensor supply active code remains active after all the sensors on the sensor supply circuit have been checked. Repair: A failed wiring harness has been detected. Repair or replace the wiring harness. Verify that the repair eliminated the problem.
3. Check the Sensor Supply A. Remove electrical power from the engine. B. Unplug the sensor from the wiring harness. C. Install the jumper wire between the following terminals at the sensor connector: - Terminal 1 (sensor supply) and Terminal 2 (sensor return) D. Connect Cat ET. E. Use Cat ET to monitor the following: - Codes	Codes	Result: A -4 code is activated on the affected sensor supply. Repair: Remove the sensor. Check the sensor passage for a blockage or obstruction. Also, check for moisture frozen in the lines. If blockage is not found, replace the sensor. Verify that the repair eliminated the problem. Result: A -4 code is not activated on the affected sensor supply. Repair: The problem is in the wiring harness from the ECM to the sensor connector. Repair or replace the wiring harness. 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).