TUBE AS 4480617 - Caterpillar

The supply voltage is routed to terminal 1 of each sensor connector. The sensor return is routed to terminal 2 of each sensor connector. For the pressure sensors, the sensor signal is routed to terminal 3 of each sensor connector. The sensor signal for the exhaust temperature sensors is routed to terminals 3 and 4 of the connector for the sensor buffer.The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Diagnostic Testing using Caterpillar Electronic Technician (ET)Wiggle Test - The wiggle test allows the technician to monitor the status of the signals from the sensors. For additional information regarding the wiggle test, refer to the documentation that accompanies the Cat ET software.
Illustration 1 g02272593
Schematic for the active sensors
Illustration 2 g02272534
Terminal locations at the P1 ECM connector for the analog sensors
(P1-2) Analog supply
(P1-3) Analog return
(P1-15) Turbocharger compressor inlet pressure sensor (right side #1)
(P1-16) Turbocharger compressor inlet pressure sensor (left side #2)
Illustration 3 g02272575
Terminal locations at the P2 ECM connector for the analog sensors
(P2-13) Front exhaust temperature sensor for the left side of the engine
(P2-15) Intake manifold pressure sensor (right side #2)
(P2-17) Analog return
(P2-27) Fuel pressure sensor (filtered fuel pressure)
(P2-28) Engine oil pressure sensor
(P2-30) Analog return
(P2-38) Rear exhaust temperature sensor for the right side of the engine
(P2-41) Intake manifold pressure sensor (left side #1)
(P2-55) Rear exhaust temperature sensor for the left side of the engine
(P2-72) Analog supply
(P2-78) Atmospheric pressure sensor
(P2-81) Analog supply
(P2-83) Analog return
(P2-91) Front exhaust temperature sensor for the right side of the engine Test Step 1. Check for Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector. Establish a connection with the engine ECM.
Turn the keyswitch to the ON position.
Look for the following codes that are active or logged:
-3
-4
-21Results:
Active -3 Code - A -3 diagnostic code is active. Proceed to Test Step 2.
Active -4 code - A -4 diagnostic code is active. Proceed to Test Step 3.
Active -21 code - A -21 diagnostic code is active.Repair: The -21 diagnostic codes indicate that the sensor is not receiving the correct supply voltage. Refer to Troubleshooting, "Sensor Supply - Test" for information that is related to troubleshooting the supply circuit for the suspect sensor.STOPTest Step 2. Create a Short at the Sensor Connector
Use a test lamp in order to create a short between terminal 3 (signal) and terminal 2 (return) at the sensor connector.
Turn the keyswitch to the ON position.
Monitor the diagnostic codes on Cat ET. Check for an active -4 diagnostic code for the suspect sensor.
Turn the keyswitch to the OFF position. Results:
Active -4 - A -4 diagnostic code became active after creating the short at the sensor connector.Repair: The wiring is OK. Replace the sensor.Verify that the problem is resolved.STOP
Active -3 - The -3 diagnostic code remains active for the suspect sensor. Proceed to Test Step 4.Test Step 3. Create an Open at the Suspect Sensor Connector
Turn the keyswitch to the OFF position.
Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic