770, 772, 773E, 773F, 777E and 777F Off-Highway Trucks and 775F Quarry Truck VIMS Truck Payload System Caterpillar

Test Step 1. PAYLOAD WEIGHT DOES NOT SEEM CORRECT FOR A GIVEN TRUCK.

The VIMS does not indicate that a diagnostic code is present for one or more of the suspension cylinder pressure sensors.

Expected Result:

No active diagnostic codes are present for one or more of the suspension cylinder pressure sensors.

Results:

• YES - The VIMS does not indicate that a diagnostic code is present for one or more of the suspension cylinder pressure sensors. proceed to test step 2.

• NO - Diagnostic codes are present for one or more of the suspension cylinder pressure sensors.

  Repair: Perform the Troubleshooting, "Suspension Cylinder Pressure Sensor" procedure that is located in this manual.

  STOP

Test Step 2. PAYLOAD WEIGHTS ONLY APPEAR TO BE INCORRECT OCCASIONALLY.

Verify that SOME of the payload measurements appear to be correct.

Expected Result:

Some of the payload measurements seem correct.

Results:

• YES - Some of the payload measurements appear to be correct. Proceed to test step 3.

• NO - All payload measurements appear to be incorrect. proceed to test step 6.

Test Step 3. CHECK FOR DIAGNOSTIC EVENTS

Verify that no “active diagnostic events” or “intermittently active diagnostic events” are present for the suspension cylinder pressure sensors or other components of the payload system.

Expected Result:

No active Diagnostic Events are present for the suspension cylinder pressure sensors. No Diagnostic Events are listed in the event list for the suspension cylinder pressure sensors.

Results:

• YES - No active Diagnostic Events are present for the suspension cylinder pressure sensors. No Diagnostic Events are listed in the event list for the suspension cylinder pressure sensors. Proceed to test step 4.

• NO - Active Diagnostic Events are present for the suspension cylinder pressure sensors. No Diagnostic Events are shown in the event list for the suspension cylinder pressure sensors.

  Repair: Perform the Troubleshooting, "Suspension Cylinder Pressure Sensor" procedure that is located in this manual.

  STOP

Test Step 4. CALIBRATE THE PAYLOAD SYSTEM.

1. Ensure that the truck body is empty. Carryback weight in the truck body can affect the payload measurements.

2. Operate the empty truck to a minimum ground speed of four mph on hard level ground.

3. Move the transmission gear selector to the neutral position and allow the truck to coast to a stop. Do not use the service brakes or the retarder.

4. After the truck stops moving, manually calibrate the payload system by entering the service program code of “729225” (PAYCAL). Then press the "OK" key. The following message will appear if the calibration was successful.

Illustration 1	g00490356

Expected Result:

The payload weights for a given truck seem correct after performing the calibration of the payload system.

Results:

• YES - The payload weights for a given truck seem correct after performing the calibration of the payload system. The condition that was responsible for the incorrect payload measurement has been eliminated. Return the truck to service.

  Repair: The condition that was responsible for the incorrect payload measurement has been eliminated. Return the truck to service.

  STOP

• NO - The payload weights for a given truck remain incorrect after performing the calibration of the payload system. Proceed to test step 5.

Test Step 5. CHECK FOR THE CORRECT PLACEMENT OF THE LOAD

Observe the loading operation. Ensure that the operator of “loading tool” is placing the load in the “truck body” in the proper area.

Illustration 2	g00670357
The 175-2624 Position Load Markers are available via MSO through the machine order system. For information on proper placement of the marker on the body, contact Decatur CMT Product Support. Product Support will need the information that is listed here: the serial number of the truck, the part number of the truck body, the sequence number of the truck body and information on modifications that have been made to the body. (1) Center of Load Marker

Expected Result:

The operator is loading the truck correctly. Refer to Illustration 2.

Results:

• YES - The operator of the loading tool is positioning the load correctly. Proceed to test step 6.

• NO - The operator of the loading tool is not positioning the load correctly in the body.

  Repair: In order to ensure that the load will be placed properly, provide the operator of the loading tool with training.

  STOP

Test Step 6. CHECK FOR ANY SERVICE WORK THAT MAY AFFECT THE MEASUREMENT OF THE PAYLOAD

Check the maintenance records of the truck for any work that may affect the VIMS components. This includes the following:

• Replacement of the body raise switch

• Work on the truck body

• Work on any other component of the payload system

Expected Result:

No work that is related to the payload system was performed on the machine.

Results:

• YES - No work that is related to the payload system was performed on the machine. Proceed to test step 7.

• NO - Work was performed on the truck that is related to the payload system. When the payload system has not not been calibrated after replacing components, proceed to Test Step 8. Service work may have an effect on the payload measurement.

Test Step 7. CHECK FOR DIAGNOSTIC EVENTS

Verify that no “active diagnostic events” or “intermittent diagnostic events” are present for the suspension cylinder pressure sensors or other components of the payload system.

Expected Result:

No active Diagnostic Events are present for the suspension cylinder pressure sensors. No Diagnostic Events are listed in the event list for the suspension cylinder pressure sensors.

Results:

• YES - No active Diagnostic Events are present for the suspension cylinder pressure sensors. No Diagnostic Events are listed in the event list for the suspension cylinder pressure sensors. Proceed to test step 8.

• NO - Active Diagnostic Events are present for the suspension cylinder pressure sensors. Diagnostic Events are shown in the event list for the suspension cylinder pressure sensors.

  Repair: Perform the Troubleshooting, "Suspension Cylinder Pressure Sensor" procedure that is located in this manual.

  STOP

Test Step 8. CALIBRATE THE PAYLOAD SYSTEM.

1. Ensure that the truck body is empty. Carryback weight in the truck body can affect the payload measurements.

2. Operate the empty truck to a minimum ground speed of four mph on hard level ground.

3. Move the transmission gear selector to the neutral position and allow the truck to coast to a stop. Do not use the service brakes or the retarder.

4. Manually calibrate the payload system by entering the service program code of “729225” (PAYCAL). Then press the "OK" key. The following message will appear if the calibration was successful.

Illustration 3	g00490356

Expected Result:

The payload weights for a given truck seem correct after performing the calibration of the payload system.

Results:

• YES - The payload weights for a given truck seem correct after performing the calibration of the payload system.

  Repair: The condition that was responsible for the incorrect payload measurement has been eliminated. Return the truck to service.

  STOP

• NO - The payload weights for a given truck remain incorrect after performing the calibration of the payload system. Proceed to test step 9.

Test Step 9. CHECK THE PAYLOAD CONFIGURATION SETTING

Check the payload configuration setting by entering the service program code 7292663 (PAYCONF) via the keypad. This will display the maximum payload weight of the truck. Verify that the payload weight is correct for the suspect truck.

Expected Result:

The payload configuration is correct.

Results:

• YES - The payload configuration is correct. Proceed to test step 10.

• NO - The payload configuration is incorrect.

  Repair: Perform the “Payload Configuration”. See the Systems Operation, "Truck Payload - Configure" section in this manual.

  STOP

Test Step 10. CHECK THE PART NUMBER OF THE VIMS ONBOARD SOFTWARE.

Verify that the correct VIMS onboard software is installed in the VIMS electronic control module. Contact the Product Support staff of the appropriate Business Unit for a list of compatible “VIMS software”. Reference the Service Magazine article that listed the available VIMS onboard software.

Expected Result:

The correct software is installed on the machine.

Results:

• YES - The correct software is installed on the machine. Proceed to test step 11.

• NO - The software is incorrect.

  Repair: Install the correct “VIMS software” and then perform the Payload Calibration. See the Systems Operation, "Truck Payload - Calibration" section in this manual.

  STOP

Test Step 11. CHECK THE SUSPENSION CYLINDERS.

Verify that the conditions that are listed below are not present.

• The suspension cylinders are NOT sticking when the truck is empty.

• The suspension cylinders are not bottoming out when the truck is loaded.

Expected Result:

The conditions that are listed above are not present.

Results:

• YES - The conditions that are listed above are not present. The cause of this failure is a failed sensor.

  Repair: Perform the Troubleshooting, "Suspension Cylinder Pressure Sensor" procedure that is located in this manual.

  STOP

• NO - The conditions that are listed above are present. The cause of the failure is an incorrectly charged suspension cylinder.

  Repair: Verify the above conditions by any of the means that are listed below.

  • Ride in the truck during the loading operation. Observe the operation of the four suspension cylinder pressure sensors. This is done with the “VIMSpc99 View Real Time” option.

  • Activate a data logger.
  Compare the signal outputs of the four sensors. Verify that the suspect sensor or the suspect suspension cylinder does not respond to truck loading in the same manner as the other sensors or suspension cylinders.

  Service the suspension cylinder in accordance with the Special Instruction, SEHS9411, "Charging Procedure for Front and Rear Suspension Cylinders".

  STOP