C3.4B Engines Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

CCS7 4B2

Note: This procedure is applicable to all engine pressure sensors except the exhaust gas pressure sensor.

This procedure covers the following codes:

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Table 1
Diagnostic Trouble Codes for the Engine Pressure Sensors
J1939 Code	Description	Notes
102-3	Engine Intake Manifold #1 Pressure : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the intake manifold air pressure sensor is greater than 4.92 V for at least 0.5 seconds. The battery voltage is at least 10 V. The ECM will use the default value for the intake manifold air pressure while this code is active. The default value is 98 kPa (14.2 psi). The warning lamp will flash. The engine will be derated.
102-4	Engine Intake Manifold #1 Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the intake manifold air pressure sensor is less than 0.2 V for at least 0.5 seconds. The battery voltage is at least 10 V. The ECM will use the default value for the intake manifold air pressure while this code is active. The default value is 98 kPa (14.2 psi). The warning lamp will flash. The engine will be derated.
108-3	Barometric Pressure : Voltage Above Normal	The ECM detects that the signal voltage from the barometric pressure sensor is greater than 4.9 V for at least 0.8 seconds. The barometric pressure sensor is contained within the ECM. The ECM will use the default value for the barometric pressure while this code is active. The default value is 97 kPa (14 psi). The warning lamp will flash. The engine will be derated.
108-4	Barometric Pressure : Voltage Below Normal	The ECM detects that the signal voltage from the barometric pressure sensor is less than 0.2 V for at least 0.8 seconds. The barometric pressure sensor is contained within the ECM. The ECM will use the default value for the barometric pressure while this code is active. The default value is 97 kPa (14 psi). The warning lamp will flash. The engine will be derated.
157-3	Engine Injector Metering Rail #1 Pressure : Voltage Above Normal	The ECM detects that the signal voltage from the fuel rail pressure sensor is greater than 4.9 V for at least 0.2 seconds. The engine will be derated. The engine may shut down.
157-4	Engine Injector Metering Rail #1 Pressure : Voltage Below Normal	The ECM detects that the signal voltage from the intake manifold air pressure sensor is less than 0.34 V for at least 0.2 seconds. The engine will be derated. The engine may shut down.
157-10	Engine Injector Metering Rail #1 Pressure : Abnormal Rate of Change	The ECM detects the following conditions: An implausible rate of change in the signal from the fuel rail pressure sensor. The condition has been detected five times within 3 seconds. There are no other active diagnostic codes for the fuel rail pressure sensor. This diagnostic code indicates an intermittent connection in the circuit for the fuel rail pressure sensor. The warning lamp will come on.
102-20	Engine Intake Manifold #1 Pressure : Data Drifted High	The ECM detects the following conditions: The intake manifold pressure is greater than 10 kPa (1.5 psi) above the barometric pressure for at least 5 seconds. The engine is not cranking. The battery voltage is greater than 10 V. The warning lamp will flash. The engine will be derated.
102-21	Engine Intake Manifold #1 Pressure : Data Drifted Low	The ECM detects the following conditions: The intake manifold pressure is greater than 10 kPa (1.5 psi) below the barometric pressure for at least 5 seconds. The engine is not cranking. The battery voltage is greater than 10 V. The warning lamp will flash. The engine will be derated.

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 V sensor supply provides power to all 5 V sensors. The ECM supplies 5.0 ± 0.1 V to each of the pressure sensor connectors. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM.

Pull-up Voltage

The ECM continuously outputs a pull-up voltage on the circuit for the sensor signal wire. This pull-up voltage is required for correct sensor operation and diagnostics.

When the sensor is disconnected, this pull-up voltage can be measured at the harness connector for the sensor.

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Illustration 1	g03732068
Schematic diagram for the engine pressure sensors

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Illustration 2	g03732070
View of the pin locations on the 62-pin engine interface connector for the pressure sensors. (5) Fuel rail pressure sensor ground (6) Fuel rail pressure sensor signal (7) Fuel rail pressure sensor 5 supply (17) Intake manifold air pressure sensor 5 V supply (18) Intake manifold air pressure sensor signal (19) Intake manifold air pressure sensor ground

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Illustration 3	g03623078
Typical view of the pin locations on the P2 connector for the pressure sensors (10) Intake manifold air pressure sensor 5 V supply (11) Fuel rail pressure sensor 5 V supply (25) Intake manifold air pressure sensor ground (26) Fuel rail pressure sensor ground (40) Intake manifold air pressure sensor signal (41) Fuel rail pressure sensor signal

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Thoroughly inspect the terminal connections on the P2/J2 ECM connector. Refer to Troubleshooting, "Electrical Connectors - Inspect". B. Thoroughly inspect the connectors for the engine pressure sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect". C. Perform a 30 N (6.7 lb) pull test on each of the wires in the ECM connector and the sensor connectors that are associated with the engine pressure sensors. D. Check the harness for abrasions and for pinch points from the engine pressure sensors back to the ECM.	Damaged wire or connector	Result: A damaged wire or damaged connector was found. Repair: Repair the damaged wire or the damaged connector. Replace any blown fuses Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, of abrasion or of pinch points. Proceed to Test Step 2.
2. Check For Active Diagnostic Codes A. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. B. Verify if any of the diagnostic codes that are listed in Table 1 are active.	Diagnostic codes	Result: A 108-3 or 108-4 diagnostic code is active. Proceed to Test Step 10. Result: A -3 or a -4 diagnostic code is active for one or more of the other pressure sensors. A 102-20 or 102-21 diagnostic code is active. Proceed to Test Step 3. Result: A 157-10 diagnostic code is active or recently logged. An intermittent connection exists in the circuit for the fuel rail pressure sensor. Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to identify intermittent connections.
3. Check the Supply Voltage at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect sensor. C. Turn the keyswitch to the ON position. Do not start the engine. D. Measure the voltage between the 5 V supply terminal and the ground terminal on the harness connector for the suspect sensor. The voltage measurement should be 5.0 ± 0.1 V. E. Turn the keyswitch to the OFF position. F. Reconnect the sensor.	4.9 V to 5.1 V	Result: The voltage measurement is not within the expected range. Proceed to Test Step 4. Result: The voltage measurement is within the expected range. Proceed to Test Step 5.
4. Check the Supply Voltage at the 62-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 62-pin connector. C. Turn the keyswitch to the ON position. Do not attempt to start the engine. D. Measure the voltage between the 5 V supply terminal and the ground terminal for the suspect sensor on the 62-pin connector on the harness between the engine and the ECM. The voltage measurement should be 5.0 ± 0.1 V. E. Turn the keyswitch to the OFF position. F. Reconnect the 62-pin connector.	4.9 V to 5.1 V	Result: The voltage measurement is 5.0 ± 0.1 V. The fault is in the 5 V supply wire or the ground wire between the 62-pin engine interface connector and the sensor. Repair: Replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault. Result: The voltage measurement is not 5.0 ± 0.1 V. The fault is in the 5 V supply wire or the ground wire between the 62-pin engine interface connector and the ECM. Repair: Replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault.
5. Verify the Type of Active Diagnostic Code A. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. B. Use the electronic service tool to check for active diagnostic codes. Record all active diagnostic codes. C. Determine if the fault is related to an open circuit diagnostic code or a short circuit diagnostic code.	Diagnostic codes	Result: A -4 diagnostic code is active for one or more of the pressure sensors at this time. Proceed to Test Step 6. Result: A -3 diagnostic code is active for one or more of the pressure sensors at this time. Proceed to Test Step 8. Result: None of the preceding diagnostic codes are active. An intermittent fault may exist. Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to identify intermittent faults.
6. Create An Open Circuit at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the sensor with the -4 diagnostic code. C. Turn the keyswitch to the ON position. Wait for at least 10 seconds for activation of the diagnostic codes. D. Use the electronic service tool to check the "Active Diagnostic Code" screen. Check for an -3 diagnostic code for the suspect sensor.	Diagnostic codes	Result: An -3 diagnostic code became active after disconnecting the sensor. Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor. If the fuel rail is replaced, use the electronic service tool to perform the "Rail Pressure Valve Learn Reset". Use the electronic service tool in order to clear all logged diagnostic codes. Result: The -4 diagnostic code is still active with the sensor disconnected. Proceed to Test Step 7.
7. Create an Open Circuit at the 62-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 62-pin connector. C. Turn the keyswitch to the ON position. Wait at least 30 seconds for activation of the diagnostic codes. Note: Diagnostic codes for all of the engine sensors will be active with the 62-pin connector disconnected. Ignore all other diagnostic codes and only look for codes relating to the suspect sensor. D. Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active -3 diagnostic code for the suspect sensor. E. Turn the keyswitch to the OFF position.	Diagnostic Codes	Result: A -3 diagnostic code for the suspect sensor became active after the 62-pin connector was disconnected. The fault is in the wiring between the suspect sensor and the 62-pin ECM connector. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The -4 diagnostic code for the suspect sensor is still active with the 62-pin connector disconnected. The fault is in the wiring between the 62-pin connector and the ECM. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
8. Create a Short at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect sensor. C. Fabricate a jumper wire that is 150 mm (6 inch) long. Install the jumper wire between the sensor signal terminal and the sensor ground terminal on the harness connector for the suspect sensor. D. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. E. Use the electronic service tool to check for an active -4 diagnostic code for the suspect sensor. F. Turn the keyswitch to the OFF position. Remove the jumper wire.	Diagnostic codes	Result: An -4 diagnostic code was active with the jumper installed. Repair: Temporarily connect a new pressure sensor to the harness, but do not install the new sensor in the engine. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor. If the fuel rail is replaced, use the electronic service tool to perform the "Rail Pressure Valve Learn Reset". Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A -3 diagnostic code is still active with the jumper installed. Proceed to Test Step 9.
9. Create a Short at the 62-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 62-pin connector. C. Fabricate a jumper wire that is 150 mm (6 inch) long. Install the jumper wire between the suspect sensor signal terminal and the sensor ground terminal on the 62-pin connector on the harness between the engine and the ECM. D. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. Note: Diagnostic codes for all of the engine sensors will be active with the 62-pin connector disconnected. Ignore all other diagnostic codes. Only look for codes that relate to the suspect sensor. E. Use the electronic service tool to check for an active -4 diagnostic code for the suspect sensor. F. Turn the keyswitch to the OFF position. Remove the jumper wire.	Diagnostic codes	Result: An -4 diagnostic code was active with the jumper installed. The fault is in the wiring between the suspect sensor and the 62-pin connector. Repair; Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A -3 diagnostic code is still active with the jumper installed. The fault is in the wiring between the 62-pin connector and the ECM. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
10. Check if a Replacement ECM Eliminates the Fault A. Contact the Dealer Solution Network (DSN). B. If the DSN recommends the use of a replacement ECM, install a replacement ECM. Refer to Troubleshooting, "Replacing the ECM". C. Use the electronic service tool to recheck the system for active diagnostic codes.	Diagnostic codes	Result: There are no active diagnostic codes with the replacement ECM. Repair: Reconnect the suspect ECM. If the fault returns with the suspect ECM, replace the ECM. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The diagnostic code is still present with the replacement ECM. Contact the DSN.
If the procedure did not correct the fault, contact the DSN.