C7.1 Engines and Generator Sets Caterpillar

Sensor Calibration Required - Test

Usage:

C7.1 770

The Electronic Control Module (ECM) performs calibrations of pressure sensors automatically. Use this procedure if the diagnostic code in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table for Sensor Calibration
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
411-13	3387-13	Engine Exhaust Gas Recirculation Differential Pressure : Out of Calibration	The ECM detects the following conditions: NRS differential pressure is outside the acceptable range during initialization check, or during sensor calibration when the engine is not running. The warning lamp will come on and the engine will be derated. The code is logged.
3358-13	3385-13	Engine Exhaust Gas Recirculation Inlet Pressure : Out of Calibration	The ECM detects the following conditions: The offset between NRS inlet pressure and barometric pressure is outside the acceptable range during initialization check. The offset between NRS inlet pressure and barometric pressure is outside the acceptable range during sensor calibration when the engine is not running. The warning lamp will come on and the engine will derate. The code is logged.
3563-13	1785-13	Engine Intake Manifold #1 Absolute Pressure : Out of Calibration	The ECM detects the following conditions: The offset between intake manifold air pressure and barometric pressure is outside the acceptable range during initialization check. The offset between the intake manifold air pressure and the barometric pressure is outside the acceptable range during sensor calibration with the engine not running. The warning lamp will come on and the engine will derate. The code is logged.
3609-13	3464-13	DPF #1 Intake Pressure : Out of Calibration	The ECM detects the following conditions: The offset between DPF intake pressure and barometric pressure is outside the acceptable range during initialization check. The offset between the intake manifold air pressure and the barometric pressure is outside the acceptable range during sensor calibration with the engine not running. The warning lamp will come on and the engine will derate. The code is logged.
3837-13	3493-13	Aftertreatment 1 Secondary Air Pressure : Out of Calibration	The ECM detects the following conditions: The offset between aftertreatment secondary air pressure and barometric pressure is outside the acceptable range during initialization check. The offset between aftertreatment secondary air pressure and barometric pressure is outside the acceptable range during sensor calibration with the engine not running. The warning lamp will come on and the engine will derate. The code is logged.

During normal operation, each pressure sensor outputs a signal voltage that accurately represents the pressure that is sensed by the sensor. However, certain circuit conditions can cause a signal voltage to become inaccurate.

During each key on event of at least 2 seconds, the Electronic Control Module (ECM) evaluates the signal voltage from each pressure sensor. The ECM compares each signal voltage to a reference voltage. The reference voltage that is used depends on the sensor.

If a signal voltage is close to the reference voltage, the ECM will internally adjust the signal voltage. The internal adjustment causes the pressure value for the sensor to be correct. This process is called automatic sensor calibration.

If a signal voltage is not close to the reference voltage, the ECM will not internally adjust the signal voltage. The ECM will set a fault code that indicates there is a problem with the signal voltage.

During the following procedure, refer to the electrical schematic for the application.

Complete the procedure in the order in which the steps are listed.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check For Active Diagnostic Codes A. Turn the keyswitch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the keyswitch to the ON position. Download the "Product Summary Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. D. Use the electronic service tool to check that coolant temperature, intake manifold air temperature, and NRS temperature are all at least 5° C (41° F). Note: Wait at least 10 seconds in order for the diagnostic codes to become active. E. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes. Look for an active or logged -3 or -4 codes for the pressure sensor or the barometric pressure sensor. F. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes. Look for an active or logged -13 code for a pressure sensor or the barometric pressure sensor. G. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: There are no active diagnostic codes for the pressure sensors. If there are logged diagnostic codes for the intake manifold pressure sensor, the fault may be intermittent. Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" to identify intermittent faults. Result: One or more of the temperature sensors is reading less than 5° C (41° F). Proceed to Test Step 4. Result: There is an active -3 or -4 diagnostic code for a pressure sensor or the barometric pressure sensor. Repair: Troubleshoot these codes before continuing with this procedure. Result:Several -13 diagnostic codes are active. Proceed to Test Step 5. Result: There is an active 3358-13 (3385-13), 3563-13 (1785-13), 3609-13 (3464-13), or 3837-13 (3493-13) diagnostic code for only one sensor. Proceed to Test Step 6. There is an active 411-13 (3387-13) diagnostic code. Proceed to Test Step 2.
2. Check the Signal Wire for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector and disconnect the connector from the suspect sensor. C. Check the resistance between the applicable signal terminal on the P2 connector and all other terminals on the P2 connector.	Greater than 100 Ohms	Result: At least one of the resistance measurements is less than 100 Ohms. The fault is in the engine harness. Repair: Repair the faulty connector or replace the faulty harness. Use the electronic service tool to verify that the repair eliminates the fault. Result: All resistance measurements are greater than 100 Ohms. Proceed to Test Step 3.
3. Create a Short Circuit 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. Crimp a terminal to both ends of the wire. D. Use the jumper to connect the sensor signal terminal to the sensor ground terminal on the harness connector for the suspect sensor. E. Turn the keyswitch to the ON position. Do not start the engine. F. Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-4 diagnostic code for the suspect sensor. G. Remove the jumper. Reconnect the sensor.	Diagnostic codes	Result: An XXXX-4 diagnostic code became active with the jumper installed. The sensor may be faulty. Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Use the electronic service tool 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: The XXXX-4 diagnostic code did not become active when the jumper is installed. Proceed to Test Step 4.
4. Ensure that the Systems are Fully Thawed A. Move the machine into an environment where the ambient temperature is greater than 5° C (41° F) during any troubleshooting. B. If engine has been operated or stored in cold ambient conditions, there is a risk of ice formation on a sensor or sensor pipes. Run the engine until the coolant temperature exceeds 65° C (149° F)for 20 minutes. C. Turn the keyswitch to the OFF position. Wait for at least 20 seconds. The electronic service tool will disconnect. D. Turn the keyswitch to the ON position. E. Verify that coolant temperature, intake manifold air temperature, and NRS temperature are all now at least 5° C (41° F). F. Check for active -13 diagnostic codes. G. Check that the suspect sensor is installed correctly. Check that the suspect sensor is fully seated into the engine.	Diagnostic codes	Result: There are no active -13 codes. The fault was caused by ice in the system that has now been thawed. Return the unit to service Result: Several -13 codes are active or logged. Proceed to Test Step 5. Result: A single -13 code is active or logged. Proceed to Test Step 6.
5. Check the Barometric Pressure Sensor A. Turn the keyswitch to the OFF position. B. Install a new barometric pressure sensor. C. Turn the keyswitch to the ON position. Do not start the engine. Note: Wait at least 10 seconds in order for the diagnostic codes to become active. D. Monitor the status parameter for the suspect sensor on the electronic service tool.	Barometric pressure sensor fault	Result: There is no active -13 code. The fault was caused by a faulty barometric pressure sensor. Use the electronic service tool to clear all logged codes. Return the unit to service. Result: Either a 3563-13, 1785-13, 3358-13, or 3386-13 code is active. Proceed to Test Step 6.

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Illustration 1	g03791820
(1) Pipe for the NRS differential pressure sensor (2) Pipe for the NRS inlet pressure sensor and the NRS differential pressure sensor

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Table 3
Troubleshooting Test Steps	Values	Results
6. Check the Suspect Pressure Sensor A. Turn the keyswitch to the OFF position. B. Disconnect the connector for the suspect sensor and remove the sensor from the engine. C. Check the sensor for a blockage. D. Temporarily reconnect the sensor to the harness. Do not install the sensor on the engine. E. Turn the keyswitch to the ON position. Do not start the engine. F. Check for an active -13 diagnostic code for the suspect sensor.	Barometric pressure sensor fault	Result: There is an active -13 code or the sensor is blocked Repair: Temporarily connect a new sensor to the harness. Use the electronic service tool to confirm that the repair eliminates the fault. If the fault is eliminated, permanently install the new sensor. Refer to Disassembly & Assembly for the correct installation procedure. If the fault is still present, proceed to Test Step 5. Result: There is no active -13 code. Check that the sensor pipes are free of blockages or restrictions. Refer to Illustration 1. If necessary, remove the pipes and clear any blockage with an air line that is set at a maximum pressure of 200 kPa (29 psi). If the blockage is cleared, reinstall the pipes. If the blockage cannot be cleared or there is a restriction, replace the pipe. Install the sensor. Refer to Disassembly & Assembly for the correct installation procedure. Turn the keyswitch to the ON position. Run the engine at idle speed for 5 minutes. Turn the keyswitch to the OFF position. Ensure that the ECM is fully powered-down. Turn the keyswitch to the ON position. Do not start the engine. Wait for 10 seconds. Confirm that the code is not active. Use the electronic service tool to clear all logged codes. If the fault is still present, contact the Dealer Solutions Network (DSN).