CABLE AS- 4977278 - Caterpillar

System OperationUse this procedure to troubleshoot any suspect problems with the following sensors:
Coolant temperature sensor
Intake manifold air temperature sensor
Fuel temperature sensorThe sensor signal for the passive sensor is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the passive sensors is routed from the ECM to terminal 2 of each sensor connector.
Illustration 1 g01303228
Typical schematic
Illustration 2 g01193814
P2 ECM connector
(P2-13) Engine coolant temperature
(P2-30) Sensor return
(P2-56) Intake manifold air temperature
(P2-62) Fuel temperature
Illustration 3 g01155187
Connector for the temperature sensors
(1) Sensor signal
(2) Sensor return
Illustration 4 g01200241
Sensor locations (typical left side engine view)
(1) Engine coolant temperature sensor
(2) Intake manifold air temperature sensor
(3) Fuel temperature sensor Test Step 1. Check for "Active" or "Logged" Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the ECM.
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). 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 in the harness to the Battery. Repair the wiring.STOPTest Step 3. Create a Short at the Sensor Connector
Remove electrical power from the ECM.
Disconnect the suspect sensor.
Use a wire jumper in order to create a short between terminal 1 (signal) and terminal 2 (sensor return) at the sensor connector.
Restore electrical power to the ECM.
Access the "Active Diagnostic Code" screen on Cat ET. Check for an active 4 diagnostic code for the suspect sensor.
Remove power from the ECM. 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, but do not install the new sensor in the engine. Verify that there are no active