PLUG-MAGNETIC 1645622 - Caterpillar

System Operation Description:This test should be used for troubleshooting opens and/or shorts in any of the analog engine sensor circuits. These sensors provide various signals to the engine ECM. These sensors receive a regulated supply of 5.0 VDC from the ECM.The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine is OFF for at least five seconds. During an automatic calibration, the ECM calibrates pressure sensors against the atmospheric pressure sensor and an acceptable offset pressure range.Note: Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test" if the ECM has detected a problem with the analog sensor supply voltage.Note: There are separate procedures for troubleshooting opens and/or shorts in digital engine sensor circuits. Refer to the appropriate topic in the "Troubleshooting with a Diagnostic Code" section of this manual.
Illustration 1 g01852233
Schematic
Illustration 2 g00894495
P1 and P2 ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect the J1/P1 ECM connector, the J2/P2 ECM connector, the J3/P3 customer connector, and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:All connectors, pins, and sockets should be completely inserted, and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Sensor Supply Voltage at the Sensor Connector
Disconnect the suspect sensor.
Turn the keyswitch to the ON position.
Use a multimeter to measure the voltage across terminal A (+5V Analog) and terminal B (Analog Return) at the harness side of the suspect sensor connector.
Turn the keyswitch to the OFF/RESET position.Expected Result:The analog sensor supply voltage should be 5.0 0.5 VDC.Results:
OK - The supply voltage is reaching the sensor. Proceed to Test Step 3.
Not OK - The supply voltage is not reaching the sensor.Repair: Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test" for the appropriate troubleshooting procedure.STOPTest Step 3. Short the Sensor Signal at the Sensor Connector
Turn the keyswitch to the OFF/RESET position.
Connect the Caterpillar Electronic Technician (Cat ET) to the service tool connector.
Disconnect the suspect sensor from the harness.
Turn the keyswitch to the ON position.
Check the active diagnostic codes on Cat ET.
Use a suitable piece of wire to short terminal B (Analog Return) and terminal C (Signal) at the harness side of the suspect sensor connector.
Check the active diagnostic codes on Cat ET.Expected Result:The FMI for the active diagnostic code should change from a "03" (Open/Short to +Battery) to a "04" (Short to Ground) when the terminals are shorted.Results:
OK - The harness appears to be OK. The problem is with the sensor.Repair: Replace the suspect sensor.Verify that the repair eliminates the problem.STOP
Not OK - Proceed to Test Step 4.Test Step 4. Measure the Resistance of the Signal Wire
Turn the keyswitch to the OFF position.
Disconnect the suspect sensor and the appropriate ECM connector for that sensor.
Measure the resistance