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

This procedure is used when a calibration of a solenoid fails. The procedure assumes that the Electronic Technician (ET) is ON after a failed calibration.

Test Step 1. CHECK THE ERROR MESSAGE

1. Check the error message on the ET screen.

Expected Result:

There is an error message.

Results:

• Active diagnostic present - The error message on the ET screen is "Active diagnostic present". Proceed to Test Step 2.

• Calibration value too large - The error message on the ET screen is "Calibration value too large". Proceed to Test Step 3.

Test Step 2. CHECK FOR DIAGNOSTIC CODES

1. Use the ET in order to check for diagnostic codes.

Expected Result:

There are no diagnostic codes present.

Results:

• YES - There are no diagnostic codes present. Proceed to Test Step 3.

• NO - Diagnostic codes are present.

  Repair: Refer to the appropriate diagnostic code procedure. See Troubleshooting, "Diagnostic Code List".

  STOP

Test Step 3. INSPECT THE HARNESS CONNECTIONS

1. Turn the disconnect switch to the OFF position.

2. Inspect all harness connections that are related to the circuit for the calibration pressure sensor. Make sure that the connectors are clean and tight.

3. Check the connectors for proper mating. Ensure that all the seals are present and in place.

4. Check the harness for signs of damage or abrasion.

5. Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector.

6. Check the exposed wires at the connectors for nicks or signs of abrasion.

7. Check for moisture inside the connector.

8. Check the connectors for dirty contacts or corroded contacts.

9. Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.

Expected Result:

The machine harness connectors are tight and free of corrosion.

Results:

• OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 4.

• NOT OK - The machine harness connectors are in need of repair.

  Repair: Repair the machine harness or replace the machine harness. Retry the component calibration.

  STOP

Test Step 4. CHECK THE CALIBRATION SENSOR CIRCUIT HIGH VOLTAGE CONDITION

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

1. The disconnect switch remains in the OFF position.

2. Disconnect the J2 connector from the Implement ECM.

3. Disconnect the connector at the Calibration Pressure Sensor

4. At the J2 connector for the Implement ECM, measure the resistance from the signal contact J2-50 (wire X805-WH) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the ECM.

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Test Step 5.

• NOT OK - The resistance is less than 5000 ohms. The machine harness has failed.

  Repair: There is a short between frame ground and the circuit for the calibration pressure sensor. Repair or replace the calibration harness. Retry the component calibration.

  STOP

Test Step 5. CHECK FOR POWER AT THE CALIBRATION PRESSURE SENSOR

1. The disconnect switch remains in the OFF position.

2. Reconnect the Implement ECM connector

3. The wiring harness remains disconnected from the calibration pressure sensor.

4. Turn the key start switch and the disconnect switch to the ON position.

5. At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the voltage supply wire (contact 1).

6. Measure the voltage from contact 1 to frame ground.

Expected Result:

The voltage is between +7 VDC to +14 VDC.

Results:

• OK - The voltage is between +7 VDC to +14 VDC. Proceed to Test Step 6.

• NOT OK - The voltage is not between +7 VDC to +14 VDC. The sensor power supply circuit in the calibration harness has failed.

  Repair: Replace or repair the calibration harness and retry the component calibration.

  STOP

Test Step 6. CHECK FOR PROPER GROUND AT THE SENSOR

1. Reconnect the calibration circuit connectors.

2. Turn the key start switch and the disconnect switch to the OFF position.

3. Remove the 7X-1710 Multimeter Probe from the voltage supply wire (contact 1).

4. At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the ground wire (contact 2).

5. Measure the resistance from contact 2 to frame ground.

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. The ground circuit is correct. Proceed to Test Step 7.

• NOT OK - The resistance is greater than 5 ohms. The ground circuit in the calibration harness has failed.

  Repair: Replace or repair the calibration harness and retry the component calibration.

  STOP

Test Step 7. CHECK FOR AN OPEN CIRCUIT.

1. The disconnect switch remains in the OFF position.

2. Disconnect the calibration harness from the sensor.

3. At the harness connector for the sensor, connect a jumper wire between contact 2 and contact 3.

4. Disconnect both connectors from the Implement ECM.

5. At the J2 connector for the ECM, measure the resistance between contact J2-50 (wire X805-WH) and contact J1-45 (wire P770-WH).

Expected Result:

The resistance measures less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. The solenoid circuit is not open. Proceed to Test Step 8.

• NOT OK - The resistance is greater than 5 ohms. The machine harness has failed.

  Repair: The calibration circuit is open in the harness. Repair or replace the calibration harness. Retry the component calibration.

  STOP

Test Step 8. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO THE +BATTERY CIRCUIT

1. The key start switch and the disconnect switch remain in the OFF position.

2. The harness remains disconnected from the sensor. Remove the jumper wire that was installed in the previous step.

3. The harness connectors remain disconnected from the Implement ECM.

4. At the J2 connector for the Implement ECM, measure the resistance between the signal contact J2-50 (wire X805-WH) and all contacts that are used in the machine harness connectors for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 9.

• NOT OK - One measurement or more resistance measurement is not correct. There is a short in the machine harness.

  Repair: The short is between signal contact J2-50 (wire X805-WH) and the circuit with the low resistance measurement. Repair or replace the wiring harness and retry the component calibration.

  STOP

Test Step 9. CHECK THE FUNCTION OF THE SENSOR THROUGH CAT ET

1. Reconnect the harness to the Calibration Sensor and the connectors to the Implement ECM

2. Turn the key start switch and the disconnect switch to the ON position.

3. Using CAT ET, begin the Implement Solenoid Valve Calibration procedure.

4. When the step in the procedure is reached that requires an Implement command to be held in full command position, the ET screen should be displaying, in the status field columns, command current measurement to the solenoid and load sense pressure measured by the Calibration Pressure Sensor. Monitor these readings during this step in the calibration procedure.

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Illustration 1	g02638296
Bowl Down Solenoid Calibration Screen

5. The initial readings should display a measured pressure of less than 250 kPa (36.2 psi) when the command current is inactive. When the command current to the solenoid becomes active, the measured pressure should be greater than 2000 kPa (290.0 psi).

Expected Result:

The Calibration Pressure Sensor measurements were in the proper range during the procedure.

Results:

• OK - The Calibration Pressure Sensor is functioning properly.

  Repair: Retry the component calibration.

  STOP

• NOT OK - The Calibration Presure Sensor measurements were not in the proper range

  Repair: If the initial pressure reading was not less than 250 kPa (36.2 psi), replace the Calibration Pressure Sensor. Retry the component calibration.

  If a pressure reading above 2000 kPa (290.0 psi) was never achieved, proceed to test step 10.

Test Step 10. CHECK THE PRESSURE AT THE TEST PORT

1. Remove the Calibration Kit for the Implement Solenoid calibrations.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates.

2. Locate the same pressure test port at the Implement Pump as used in the solenoid calibrations.

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Illustration 2	g02627458
Pressure Test Port

3. Connect one end of 177-7861 Hose As from 1U-5482 Pressure Adapter Group to 8T-0852 Pressure Gauge from the 1U-5481 Pressure Gauge Group. Connect the other end of the hose to the pressure tap (implement pump).

   Note: Use a hose long enough to reach the cab. If a helper is available, use a hose long enough to be read by the helper from a safe distance away from any machine movement.

4. Move the bowl, apron, and ejector in both directions and observe the pressure gauge.

Expected Result:

The pressure rises above 2000 kPa (290.08000 psi).

Results:

• OK - The pressure rises above 2000 kPa (290.0 psi). The Calibration Kit may have a failure.

  Repair: Replace the Calibration Kit and perform the calibration again with the new service tool.

  STOP

• NOT OK - The pressure does not rise above 2000 kPa (290.0 psi).

  Repair: Refer to Troubleshooting, KENR9477, "621H, 623H, and 627H Hydraulic and Steering Systems" for further assistance.

  STOP