5130, 5130B and 5230 Excavators, 784B, 785B, 785C, 789B, 789C, 793B and 793C Off-Highway Truck/Tractors and 992G, 994 and 994D Wheel Loaders Vital Information Management System (VIMS) Caterpillar

Illustration 1	g00774499
Schematic of the Left Front Suspension Cylinder

Illustration 2	g00774502
Schematic of the Right Front Suspension Cylinder

Illustration 3	g00774507
Schematic of the Left Rear Suspension Cylinder

Illustration 4	g00774508
Schematic of the Right Rear Suspension Cylinder

Note: In addition to the Testing and Adjusting, "Suspension Cylinder Pressure Sensor -Troubleshoot "procedure, the VIMS diagnostics are helpful in the troubleshooting of sensors.

Use this procedure to troubleshoot the suspect performance of suspension cylinder pressure sensors or any failure that is associated with the suspension cylinder pressure sensors.

Note: This test checks for sensor voltages at the sensor when all the circuits are connected. DISCONNECT NOTHING, unless directed to do so. Troubleshoot the circuit "as is" before disconnecting any circuits. Disconnecting the sensor from the harness before measuring the voltage may alter a poor connection. This will make the proof of cause difficult or impossible.

Locate the suspect sensor. Identify the sensor wires and connector contacts. DO NOT DISCONNECT ANY HARNESS CONNECTORS AT THIS TIME. Turn the key start switch to the ON position. Do not shut off the engine, unless conditions require the engine to be on. The truck can be empty or the truck can be loaded.

1. CHECK THE SENSOR SUPPLY VOLTAGE.

   1. At the connector of the sensor, identify the +V circuit and the ground circuit.

   2. Insert the 7X-1710 Multimeter Probe leads into the back of the sensor's connector along side of "+V" and ground circuit wires.

   3. Measure the system voltage.

      Expected Results: The voltage is between 22.0 DCV and 29.5 DCV.

      Note: System voltage at the battery must be above 24.3 DCV.

      Results:

      • YES - The voltage is between 22.0 DCV and 29.5 DCV. The system voltage is present. Proceed to test step 2.

      • NO - The voltage is less than 22.0 DCV. The circuit is not correct. Trace the "+V" circuit and the ground circuit in the machine harness. Repair the machine harness or replace the machine harness. If the machine harness has not failed the sensor is the cause of the failure. Replace the sensor. A failed sensor is unlikely. STOP.

2. CHECK THE SENSOR SIGNAL VOLTAGE.

   1. At the sensor connector, identify the signal and ground circuits.

   2. Insert the 7X-1710 Multimeter Probe leads into the back of the sensor's connector along side of the signal and ground circuit wires.

   3. Measure the signal voltage.

      Expected Results: The signal voltage is between approximately 1.0 DCV and 9.0 DCV.

      Results:

      • The voltage is greater than 9.0 DCV. The signal voltage is not correct. Proceed to test step 3.

      • The voltage is less than 1.0 DCV. The signal voltage is not correct. Proceed to test step 4.

      • The voltage is between 1.0 DCV and 9.0 DCV. The signal circuit is correct. Proceed to test step 5.

3. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO THE +BATTERY CIRCUIT.

   1. Disconnect the sensor from the machine harness.

   2. At the machine harness connector for the sensor, measure the voltage between the signal contact and the ground contact.

      Expected Results: The voltage is above 9.0 DCV.

      Results:

      • YES - The voltage is above 9.0 DCV. The signal circuit is shorted to the +battery circuit or the VIMS interface module has failed. Trace the signal circuit and the ground circuits in the harness. Repair the harness or replace the harness. If the harness is correct, the VIMS interface module has failed. Replace the VIMS interface module. STOP.

      • NO - The voltage is between 1.0 and 9.0 DCV. The voltage is correct. The sensor has failed. Replace the sensor. STOP.

4. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND.

   1. Disconnect the sensor from the machine harness.

   2. At the machine harness connector for the sensor, measure the voltage between the signal contact and the ground contact.

      Expected Results: The voltage is less than 1.0 DCV.

      Results:

      • YES -The voltage is less than 1.0 DCV. The possible cause of the failure is listed here: The incorrect VIMS onboard software is installed, the signal circuit is shorted to ground in the machine harness or the VIMS interface module has failed. Verify the possible causes in the order that is listed below:

      Verify that the correct VIMS onboard software is installed. Install the correct VIMS onboard software.

      If the software is correct, trace the signal circuit and the ground circuit in the harness. Repair the harness or replace the harness.

      If the harness is correct, the VIMS interface module has failed. Replace the VIMS interface module.

      STOP.

      • NO - The voltage is between 1.0 and 9.0 DCV. The voltage is correct. The sensor has failed. Replace the sensor.

      STOP.

5. CHECK THE FREQUENCY OF THE SENSOR SIGNAL.

   1. Remove the SENSOR from the suspension cylinder. This is done so the sensor can not sense the pressure within the suspension cylinder. DO NOT DISCONNECT THE HARNESS CONNECTOR.

   2. At the machine harness connector of the sensor, identify the signal and ground circuits. DO NOT DISCONNECT THE HARNESS CONNECTOR OR RECONNECT THE HARNESS CONNECTOR.

   3. Insert the 7X-1710 Multimeter Probe leads into the back of the sensor's connector along side of the signal and ground circuit wires.

   4. Measure the frequency between the signal and the ground contacts.

      Expected Results: The frequency is between 186 Hz and 214 Hz.

      Results:

      • YES - The frequency is between 186 Hz and 214 Hz when ambient temperature is between 10 °C (50 °F) and 40 °C (104 °F). The sensor is generating a valid frequency. If the problem of incorrect payload measurement persists proceed to test step 6.

      • NO -The frequency is NOT between 186 Hz and 214 Hz. The sensor is generating an incorrect frequency. The sensor has failed. Replace the sensor. STOP.

6. MOVE THE SENSOR.

   1. Substitute the suspect sensor with a sensor that is functioning correctly. For example, substitute a good left rear suspension cylinder pressure sensor with the suspect right rear suspension cylinder pressure sensor.

   2. Verify that the problem followed the suspect sensor to the other suspension cylinder. The service technician can verify that the problem followed the suspect sensor by riding in the truck during the loading operation. The service technician can observe the performance of the four suspension cylinder pressure sensors by using the "VIMSpc99 View Real Time" option. The service technician can also activate a "data logger". Compare the signal outputs of the four sensors. Verify that the suspect sensor does not respond to the loading of the truck in the same manner as the other sensors.

      Expected Results: The problem followed the sensor to the other suspension cylinder.

      Results:

      • YES - The problem followed the sensor to the other suspension cylinder. The sensor has failed. Replace the sensor. STOP.

      • NO - The problem did not follow the sensor to the other suspension cylinder. The suspension cylinder is causing the failure. Proceed to test step 7.

7. CHECK THE SUSPENSION CYLINDERS.

   1. 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.

      The service technician can verify that the conditions that are listed above are present by riding in the truck during the loading operation. The service technician can observe the operation of the four suspension cylinder pressure sensors with the "VIMSpc99 View Real Time" option. The service technician may also activate a "data logger" in order to observe the performance of the suspension cylinder. Compare the signal outputs of the four sensors. Verify that the sensor responds to the loading of the truck in the same manner as the other sensors.

      Expected Results: The conditions that are listed above are not present.

      Results:

      • YES -The conditions that are listed above are not present. Perform the “Payload System - Troubleshoot procedure” that is provided below.

      • NO - The conditions that are listed above are present. Service the suspension cylinder in accordance with the Special Instruction, SEHS9411, "Charging Procedure for Front and Rear Suspension Cylinders". STOP.

Payload System - Troubleshoot

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

   Result:

   • 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. Perform the Testing and Adjusting, "Suspension Cylinder Pressure Sensor -Troubleshoot " procedure that is listed above. STOP.

2. PAYLOAD WEIGHTS ONLY APPEAR TO BE INCORRECT OCCASIONALLY.

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

      Expected Result: SOME of the payload measurements seem correct.

      Result:

      • 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.

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. There are no diagnostic events listed in the event list for the suspension cylinder pressure sensors.

   Result:

   • YES - No active diagnostic events are present for the suspension cylinder pressure sensors and there are no diagnostic events listed in the event list for the suspension cylinder pressure sensors. Proceed to test step 4.

   • NO - There are active diagnostic events present for the suspension cylinder pressure sensors or there are diagnostic events shown in the event list for the suspension cylinder pressure sensors. Perform the Testing and Adjusting, "Suspension Cylinder Pressure Sensor -Troubleshoot " procedure that is listed above. STOP.

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.
      Show/hide table

      Table 2

      PAYLOAD CALIBRATED

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

      Result:

      • 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. STOP.

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

5. CHECK FOR THE CORRECT PLACEMENT OF THE LOAD
   Show/hide table

   Illustration 5	g00670357
   The 175-2624 Center of Load Markers are available via MSO through the machine order system. For information on proper placement of the marker on the body, contact your Caterpillar Dealer. 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 (such as side board or tail extensions). (1) Center of Load Marker

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

      Expected Result: The operator is loading the truck correctly. Refer to Illustration 5.

      Result:

      • 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. Provide the operator of the loading tool with training/supervision in order to ensure that the load will be placed properly. STOP.

6. CHECK FOR SERVICE WORK THAT MAY HAVE AN AFFECT ON THE MEASUREMENT OF THE PAYLOAD.

   Check the maintenance records of the suspect truck for any work that was performed on the suspension CYLINDERS or payload related VIMS components. This includes replacement of the body raise switch, the truck body or any other payload related component.

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

   Result:

   • 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. If the payload system was not calibrated after the components were replaced, proceed to test step 8. Otherwise, analyze the possible effects that the service work could have had on payload accuracy.

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 and there are no diagnostic events listed in the event list for the suspension cylinder pressure sensors.

   Result:

   • YES - No active diagnostic events are present for the suspension cylinder pressure sensors and there are no diagnostic events listed in the event list for the suspension cylinder pressure sensors. Proceed to test step 8.

   • NO - There are active diagnostic events present for the suspension cylinder pressure sensors or there are diagnostic events shown in the event list for the suspension cylinder pressure sensors. Perform the Testing and Adjusting, "Suspension Cylinder Pressure Sensor -Troubleshoot " procedure that is listed above. STOP.

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. 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.
      Show/hide table

      Table 3

      PAYLOAD CALIBRATED

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

      Result:

      • 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. STOP.

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

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.

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   Table 4

   Maximum Payload Weight by Model(1)
   Model	Maximum Payload Weight
   	Tonnes	Tons
   785B 785C	136	150
   789B 789C	177	195
   793B 793C	219	240

   Show/hide table

   (1)	The information in this table was obtained from the Caterpillar Performance Handbook, Edition 30.

   Expected Result: The payload configuration is correct.

   Result:

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

   • NO - The payload configuration is incorrect. Perform the Payload Configuration procedure that is located in the Systems Operation, "TPS Service Operation" section of this manual. STOP.

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

    Verify that the correct VIMS onboard software is installed in the VIMS interface module. Contact the Product Support staff of the appropriate Business Unit for a list of compatible VIMS software or reference the Service Magazine announcement that listed the available VIMS onboard software.

    Expected Result: The correct software is installed on the machine.

    Result:

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

    • NO - The software is incorrect. Install the correct VIMS software and then perform the Payload Calibration. The "Payload Calibration " procedure is located in the of the Systems Operation, "TPS Service Operation" section of this manual. STOP.

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.

    Result:

    • YES - The conditions that are listed above are not present. This failure was likely caused by a failed sensor. Perform the Troubleshooting, "Suspension Cylinder Pressure Sensor - Troubleshoot" procedure. STOP.

    • NO - The conditions that are listed above are present. The cause of the failure is likely related to an incorrectly charged suspension cylinder. The service technician can verify that the conditions that are listed above are present by any of the means listed below:

    The service technician can ride in the truck during the loading operation. During the loading operation the service technician observes the operation of the four suspension cylinder pressure sensors. This is done with the "VIMSpc99 View Real Time" option.

    The service technician can 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, SEHS9411-01, April 1992, "Charging Procedure for Front and Rear Suspension Cylinders". STOP.