C3.4B Engines Caterpillar

Sensor Signal (Analog, Active) - Test - Exhaust Gas Pressure Sensor

Usage:

CCS7 4B2

This procedure covers the following codes:

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Table 1
Diagnostic Trouble Codes for the Exhaust Gas Pressure Sensor
J1939 Code	Description	Notes
1209-3	Engine Exhaust Gas Pressure : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the exhaust gas pressure sensor is greater than 4.74 VDC for at least 1.8 seconds. The battery voltage is at least 10 VDC. The ECM will use the default value for exhaust gas pressure while this code is active. The default value is 50 kPa (7.25 psi). The warning lamp will flash. The engine will be derated.
1209-4	Engine Exhaust Gas Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the exhaust gas pressure sensor is less than 0.4 VDC for at least 1.8 seconds. The battery voltage is at least 10 VDC. The ECM will use the default value for exhaust gas pressure while this code is active. The default value is 50 kPa (7.25 psi). 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.

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Illustration 1	g03732081
Schematic diagram for the exhaust gas pressure sensor

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Illustration 2	g03732082
View of the pin locations on the 62-pin connector for the exhaust gas pressure sensor (21) Exhaust gas pressure sensor 5 V supply (22) Exhaust gas pressure sensor ground (23) Exhaust gas pressure sensor signal

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Illustration 3	g03732083
View of the pin locations on the P1 connector for the exhaust gas pressure sensor (18) Exhaust gas pressure sensor 5 V supply (37) Exhaust gas pressure sensor ground (57) Exhaust gas 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 connector for the exhaust gas pressure sensor. 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 exhaust gas pressure sensor. D. Check the harness for abrasions and for pinch points from the exhaust gas pressure sensor 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. 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: None of the preceding diagnostic codes are active. Repair: If the codes in Table 1 are logged, an intermittent condition may be causing the logged codes. Refer to Troubleshooting, "Electrical Connectors - Inspect". Result: A 1209-3 or a 1209-4 diagnostic code is active. Proceed to Test Step 3.
3. Check the Supply Voltage at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the exhaust gas pressure sensor. C. Turn the keyswitch to the ON position. Do not start the engine. D. Measure the voltage between terminal 1 and terminal 2 on the harness connector for the exhaust gas pressure sensor. The voltage measurement should be 5.0 ± 0.1 VDC. 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 terminal 21 and terminal 22 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 1209-3 diagnostic code is active. Proceed to Test Step 6. Result: A 1209-4 diagnostic code is active. Proceed to Test Step 8. Result: Neither 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 exhaust gas pressure sensor. 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 active 1209-4 diagnostic code.	Diagnostic codes	Result: A 1209-4 diagnostic code became active after disconnecting the sensor. Repair: Temporarily connect a new exhaust gas 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. Use the electronic service tool in order to clear all logged diagnostic codes. Clear all logged diagnostic codes. Result: The 1209-3 diagnostic code is still active with the exhaust gas pressure 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 a 1209 diagnostic code. D. Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active 1209-3 diagnostic code for the suspect sensor. E. Turn the keyswitch to the OFF position.	Diagnostic Codes	Result: A 1209-3 diagnostic code 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 1209-4 diagnostic code 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 exhaust gas pressure sensor. C. Fabricate a jumper wire that is 150 mm (6 inch) long. Install the jumper wire between terminal 1 and terminal 3 on the harness connector for the exhaust gas pressure 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 1209-3 diagnostic code. F. Turn the keyswitch to the OFF position. Remove the jumper wire.	Diagnostic codes	Result: A 1209-3 diagnostic code was active with the jumper installed. Repair: Temporarily connect a new exhaust gas 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. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 1209-4 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 terminal 21 and terminal 23 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 1209 diagnostic codes. E. Use the electronic service tool to check for an active 1209-4 diagnostic code. F. Turn the keyswitch to the OFF position. Remove the jumper wire.	Diagnostic codes	Result: A 1209-4 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 1209-3 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.
If the procedure did not correct the fault, contact the Dealer Solution Network (DSN).