BASE AS-JOYSTICK 4338500 - 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 g03884043
Illustration 2 g02151854
Terminal locations at the P1 ECM connector for the analog sensors
(P1-2) Analog supply
(P1-3) Analog return
(P1-15) Auxiliary pressure sensor
Illustration 3 g03885087
Terminal locations at the P2 ECM connector for the analog sensors
(P2-15) Intake manifold pressure sensor (left-hand)
(P2-27) Fuel pressure after filter sensor
(P2-28) Engine oil pressure sensor
(P2-30) Analog return
(P2-33) Crankcase pressure sensor
(P2-40) NRS differential pressure sensor
(P2-41) Intake manifold pressure sensor (right-hand)
(P2-27) Fuel pressure before filter sensor
(P2-72) Analog supply
(P2-74) NRS absolute pressure sensor
(P2-78) Barometric pressure sensor
(P2-80) Analog supply
(P2-81) Analog supply
(P2-82) Analog supply
(P2-83) Analog return
(P2-93) Analog return 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 -10 or -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 Code - 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 Code - 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 code.
Turn the keyswitch to the ON position.
Monitor the diagnostic codes on Cat ET. Check for an active -3 diagnostic code for the suspect sensor.
Turn the keyswitch to the OFF position. Results:
Active -3 Code - A -3 diagnostic code became active after disconnecting