COUPLER AS 2520426 - Caterpillar

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Schematic
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P2 ECM connector
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P1 ECM connector
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Sensor connectorTest Step 1. Disconnect the ECM Connectors
Turn the keyswitch to the OFF position.
Connect the Caterpillar Electronic Technician (Cat ET) to the service tool connector.
Disconnect the P1 ECM connector and the P2 ECM connector from the ECM.
Check the connectors for corrosion and moisture.
Connect a 140-2266 Cable (Seventy-Pin Breakout) at the J1/P1 ECM connector.
Turn the keyswitch to the ON position.
Check for active diagnostic codes on Cat ET.Note: An open circuit diagnostic code should be active for all of the engine pressure sensors.Expected Result:The 5 volt diagnostic codes are not active. An open circuit diagnostic code is active for all of the engine pressure sensors.Results:
OK - The 5 volt diagnostic codes are not active.Repair: Reconnect the P2 ECM connector. Remove the breakout T. Reconnect the P1 ECM connector. Proceed to Test Step 2.
Not OK - The 5 volt diagnostic codes are still active.Repair: Connect a test ECM.If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns, permanently install the new ECM.Verify that the repair eliminates the problem.STOPTest Step 2. Disconnect the Sensors
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET.
Disconnect the pressure sensors one at a time. Wait for 30 seconds after each pressure sensor is disconnected.Note: The 5 volt diagnostic code will become inactive if a pressure sensor is the cause of the 5 volt diagnostic code.
Ensure that all of the pressure sensors are disconnected.Expected Result:The 5 volt diagnostic code is still active when all of the pressure sensors are disconnected.Results:
OK - The 5 volt diagnostic code is still active.Repair: Leave all of the pressure sensors disconnected. Proceed to Test Step 4.
Not OK - The 5 volt diagnostic code disappears when the pressure sensors are disconnected. Repair: Reconnect all of the pressure sensors except the suspect sensor. Proceed to Test Step 3.Test Step 3. Check the Signal Wire
Turn the keyswitch to the ON position.Note: The suspect sensor should be disconnected.
Measure the voltage between terminal C (Signal) and terminal B (Common) of the connector for the suspect sensor on the engine harness.Expected Result:The voltage is less than 7.0 VDC.Results:
OK - The voltage is less than 7.0 VDC.Repair: Temporarily connect a new sensor.If the problem is resolved with the new sensor, reconnect the suspect sensor.If the problem returns, replace the suspect sensor.Verify that the repair eliminates the problem.STOP
Not OK - The voltage is greater than 7.0 VDC.Repair: Inspect the signal wire for a short circuit to a voltage source.Repair the signal wire or replace the signal wire.Verify that the repair eliminates the problem.STOPTest Step 4. Determine the Condition that is Present
Turn the keyswitch to the ON position.
Access the active diagnostic code screen on Cat ET.Expected Result:262-03 or 262-04 is active.Results:
262-03 - Proceed to Test Step 5.
262-04 - Proceed to Test Step 7.Test Step 5. Measure the 5 Volt Supply to the Sensor
Turn the keyswitch to the ON position.Note: All of the pressure sensors should be disconnected.
Measure the voltage between terminal A (+5V) and