C2.2 Engines For Caterpillar Built Machines Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

239D BL9

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Codes for the Active Analog Sensors
J1939 Code	Code Description	Comments
102-3	Engine Intake Manifold #1 Pressure : Voltage Above Normal	The Electronic Control Module (ECM) detects a signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
102-4	Engine Intake Manifold #1 Pressure : Voltage Below Normal	The ECM detects a signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
108-3	Barometric Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. This sensor is integrated into the engine ECM. Contact the Dealer Solutions Network (DSN) for advice.
108-4	Barometric Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. This sensor is integrated into the engine ECM. Contact the Dealer Solutions Network (DSN) for advice.
157-3	Engine Injector Metering Rail #1 Pressure : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
157-4	Engine Injector Metering Rail #1 Pressure : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
Follow the troubleshooting procedure to identify the root cause of the fault.

The following conditions must exist before any of the above codes will become active:

There are no active 3509 codes.
There are no active 168 codes.

The following background information is related to this procedure:

The 5 VDC sensor supply provides power to all 5 VDC sensors. The ECM supplies 5 VDC to terminal "1" of the fuel rail pressure sensor connector and to terminal "3" of the inlet manifold pressure sensor. The sensor common from the ECM connector goes to terminal "3" of the connector for the fuel rail pressure sensor. The sensor common from the ECM connector goes to terminal "2" of the inlet manifold pressure sensor.

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Illustration 1	g06030260
Schematic for the active sensors

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Illustration 2	g03834424
Fuel rail pressure sensor (1) 5 VDC Supply (2) Signal (3) Ground

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Illustration 3	g03834769
Intake manifold pressure sensor (1) Signal (2) Ground (3) 5 VDC Supply

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Codes A. Establish communication between the electronic service tool and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Turn the keyswitch to the ON position. C. Look for a -3, or -4 active or logged code:	Diagnostic code	Result: A 157-X diagnostic code is active. Proceed to Test Step 2. Result: A 102-X diagnostic code is active. Proceed to Test Step 4. Result: A 108-X diagnostic code is active. Contact the Dealer Solutions Network (DSN).
2. Check the Wiring between the Fuel Rail Pressure Sensor and the ECM for an Open Circuit Refer to Illustration 1. A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the fuel rail pressure sensor. C. Disconnect the engine interface connector. D. Disconnect the J2 connector from the ECM. E. Measure the resistance between the following pairs of pins: · Pin 1 on the sensor harness connector and pin 27 on the engine interface connector. · Pin 2 on the sensor harness connector and pins 23 and 24 on the engine interface connector. · Pin 3 on the sensor harness connector and pin 8 on the engine interface connector. · Pin 27 on the engine interface connector and J2:45. · Pin 23 on the engine interface connector and J2:40. · Pin 24 on the engine interface connector and J2:41. · Pin 8 on the engine interface connector and J2:16. F. Reconnect the harness connector to the fuel rail pressure sensor. G. Reconnect the engine interface connector. H. Reconnect the J2 connector to the ECM.	Less than 2.0 Ohms	Result: One of the resistance measurements is more than 2.0 Ohms. Repair: Repair or replace the wiring harness. Clear the diagnostic code and confirm that the fault has been eliminated. Result: All the resistance measurements are less than 2.0 Ohms. Proceed to Test Step 3.
3. Check the Input Voltage at the Fuel Rail Pressure Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the fuel rail pressure sensor. B. Turn the keyswitch to the ON position. C. Measure the voltage between pins 1 and 3 on the harness connector. Refer to Illustration 2. D. Turn the keyswitch to the OFF position. B. Reconnect the harness connector to the fuel rail pressure sensor.	4.5 VDC to 5.5 VDC	Result: The measured voltage is between 4.5 and 5.5 VDC. Replace the sensor. Clear the diagnostic code and confirm that the fault has been eliminated. Result: The measured voltage is less than 4.5 VDC or more than 5.5 VDC. Contact the Dealer Solutions Network (DSN).
4. Check the Wiring between the Inlet Manifold Pressure Sensor and the ECM for an Open Circuit Refer to Illustration 1. A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the inlet manifold pressure sensor. C. Disconnect the engine interface connector. D. Disconnect the J2 connector from the ECM. E. Measure the resistance between the following pairs of pins: · Pin 1 on the sensor harness connector and pin 30 on the engine interface connector. · Pin 2 on the sensor harness connector and pin 6 on the engine interface connector. · Pin 3 on the sensor harness connector and pin 13 on the engine interface connector. · Pin 30 on the engine interface connector and J2:61. · Pin 6 on the engine interface connector and J2:14. · Pin 13 on the engine interface connector and J2:23. F. Reconnect the harness connector to the inlet manifold pressure sensor. G. Reconnect the engine interface connector. H. Reconnect the J2 connector to the ECM.	Less than 2.0 Ohms	Result: One of the resistance measurements is more than 2.0 Ohms. Repair: Repair or replace the wiring harness. Clear the diagnostic code and confirm that the fault has been eliminated. Result: All the resistance measurements are less than 2.0 Ohms. Proceed to Test Step 5.
5. Check the Input Voltage at the Inlet Manifold Pressure Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector from the inlet manifold pressure sensor. B. Turn the keyswitch to the ON position. C. Measure the voltage between pins 2 and 3 on the harness connector. Refer to Illustration 3. D. Turn the keyswitch to the OFF position. B. Reconnect the harness connector to the inlet manifold pressure sensor.	4.5 VDC to 5.5 VDC	Result: The measured voltage is between 4.5 and 5.5 VDC. Replace the sensor. Clear the diagnostic code and confirm that the fault has been eliminated. Result: The measured voltage is less than 4.5 VDC or more than 5.5 VDC. Contact the Dealer Solutions Network (DSN).