621H, 623H and 627H Wheel Tractor-Scrapers Implement Electronic Control System Caterpillar

This procedure is used when the automatic ejector function does not operate, and there are no active diagnostic codes.

Test Step 1. CHECK THE MECHANISM OF THE EJECTOR.

1. Stop the machine, and turn the Key Start switch and the battery disconnect to the OFF position.

2. Check the area behind the ejector for obstructions of any kind.

Expected Result:

There are obstructions that are impeding the operation of the ejector.

Results:

• YES - There are obstructions that are impeding the operation of the ejector return.

  Repair: Remove the obstructions and resume normal machine operation.

  STOP

• NO - There are no obstructions that are impeding the operation of the ejector return. Proceed to Test Step 2.

Test Step 2. CHECK THE EJECTOR ROD END PRESSURE SENSOR.

For this step, Cat ET will be used to check the Ejector Rod End Pressure Sensor. The battery disconnect and Key Start switch should be in the ON position.

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Illustration 1	g02618978
Communication Adapter, Cables, and Cat ET Software

1. Connect a laptop and a Communication Adapter to the machine. The laptop must have the latest version of the Cat ET software. Refer to the Troubleshooting, "Service Tools" section of this manual.

2. Select the "Implement ECM" and press "OK".

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Illustration 2	g02644602
Status Screen

3. Navigate to the Status screen and observe the Ejector Rod End Pressure.

4. Start the machine and observe the pressure.

Expected Result:

With no Ejector Return command, there should be a pressure of less than 250 kPa (36.2 psi).

The pressures to stop the Ejector Auto Return are as follows:

• 24400 kPa (3538.9 psi) for the 627H and 621H

• 18000 kPa (2610.7 psi) for the 623H

The observed pressure should not be above the given values until the cylinder has fully retracted.

Results:

• NO - The pressure observe through Cat ET is above the Auto Return stop pressure and the Ejector Cylinder is not fully retracted.

  Repair: The Ejector Rod End Pressure Sensor has likely been damaged or failed. Replace the sensor and resume normal operation.

  STOP

• YES - The pressure observed in Cat ET shows that the pressures at the cylinder are in the normal range.

  Repair: It is unlikely that the ECM has failed. First try flashing the Implement ECM with the latest software and perform this procedure again. If the Ejector Auto Return continues to not function, the ECM may have failed. Prior to replacing an ECM, always contact your dealership Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, See Testing and Adjusting, "Electronic Control Module (ECM) - Replace" section of this manual for additional information.

  STOP