CLIP 3992810 - Caterpillar

Operation Description:The Caterpillar Underspeed control system varies the hydraulic pump flow in order to maintain the correct engine speed. The power shift pressure sensor is used to measure power shift pressure during the calibration procedure. After the calibration is complete, the Electronic Control Module (ECM) will use engine speed, throttle input signal, and calibration data in order to control the flow of the hydraulic pump. The output of the pump is controlled by adjusting the pulse width modulation to the power shift solenoid.The underspeed control system must be calibrated if one of the following components is replaced:
Power shift pressure sensor
Power shift solenoid
ECMThe ECM will default to a preset map for pressure if the system is out of calibration. This may cause "lack of power" complaints from the operator.Note: The term "power shift" does not refer to the transmission of the machine.Test Step 1. Start the Engine and Check for Active Diagnostic Codes.
Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector.
Start the engine.
Turn the keyswitch to the "ON" position.
Operate the machine controls in order to bring the hydraulic system to normal operating temperature.
Check for any active diagnostic codes.Expected Result:There are no active diagnostic codes.Results:
OK - Proceed to Test Step 2.
Not OK - A calibration cannot be performed. Perform the appropriate troubleshooting procedure for the Active Diagnostic Code.Test Step 2. Calibrate the Caterpillar Underspeed Control System.Select "Power Shift Solenoid Calibration" from the "Calibrations" menu on Cat ET.Note: The ECM will vary engine speed during the calibration. Do not operate the machine controls while the calibration is being performed. Do not disconnect Cat ET while the calibration is being performed.Cat ET will display the results of the calibration.The following list describes the reasons for a failed calibration procedure:"Machine was moved" - The throttle switch, the AESC enable switch, or the AESC resolver switch was changed during the calibration procedure. The engine speed is not within 15 rpm of the "Hi" and "Low" calibration values."Active Diagnostics" - There is an Active Diagnostic Code with the power shift solenoid, the power shift pressure sensor, or the throttle switch."Hydraulic Circuit Not Responding" - The power shift pressure does not correspond to the power shift solenoid."Engine Not Running" - The engine was not running before the calibration procedure was started, or the engine was stopped during the procedure.Expected Result:The calibration procedure was successful.Results:
OK - Stop.
Not OK - Repair: Cat ET will indicate the reason for the failure of the calibration. Correct the problem. Repeat Test Step 2.