Illustration 1 g01418511 Schematic for the passive analog sensors Illustration 2 g01418512 Terminal locations at the P2 ECM connector for the passive analog sensors (P2-13) Engine coolant temperature (P2-30) Analog sensor return (P2-56) Intake manifold air temperature (P2-62) Fuel temperature Illustration 3 g01155187 Terminal locations at the connector for the passive analog sensors (Terminal 1) Sensor signal (Terminal 2) Analog sensor returnTest Step 1. Check for "Active" and "Logged" Diagnostic Codes Turn the keyswitch to the OFF position. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Turn the keyswitch to the ON position. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.Note: Wait at least 30 seconds in order for the diagnostic codes to become active. Determine if a diagnostic code has occurred several times.Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection between a socket and a pin in a connector or of a poor connection between a wire and a terminal. Determine if the problem is active and related to one of the following diagnostic codes: -3 -4Expected Result:A diagnostic code is not active.Results: OK - A diagnostic code is not active.Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP Not OK - An active -3 diagnostic code is present. Proceed to Test Step 2. Not OK - An active -4 diagnostic code is present. Proceed to Test Step 4.Test Step 2. Check for Battery Voltage on the Signal Wire Measure the voltage on the harness side of the sensor connector between pin 1 and engine ground for the suspect sensor(s). Turn the keyswitch to the OFF position.Expected Result:The signal voltage is less than battery voltage.Results: OK - The signal voltage is less than battery voltage. Proceed to Test Step 3. Not OK - The signal voltage is equal to battery voltage.Repair: There is a short circuit to battery voltage in the harness. Repair the wiring harness or replace the wiring harness. Verify that the repair has resolved the original problem.STOPTest Step 3. Create a Short Circuit at the Connector for the Suspect Sensor Disconnect the suspect sensor. Fabricate a jumper wire that is long enough to create a test circuit across the harness side of the sensor connector. Crimp connector pins to each end of the jumper wire. Install the jumper wire between terminal 1 (sensor signal) and terminal 2 (sensor return) at the sensor connector. Turn the keyswitch to the ON position. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -4 diagnostic code for the suspect sensor.Wait at least 30 seconds in order for the diagnostic codes to become active. Turn the keyswitch to the OFF position.Expected Result:A -4 diagnostic code is now active for the suspect sensor(s).Results: OK - A -3 diagnostic code was active before creating the short at the sensor connector. A -4 diagnostic code became active after creating the short at the sensor connector. The wiring between the ECM and the sensor connector is OK.Repair: Temporarily connect a new sensor to the harness,
