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


Lift or Tilt Cylinder Sensor - Troubleshoot

Usage:

793B 1HL


Illustration 1g00508961
Schematic of the Lift Cylinder Head Pressure Sensor


Illustration 2g00508965
Schematic of the Tilt Cylinder Rod Pressure Sensor

Table 1
Tools Needed 
9U-7330  Multimeter 
7X-1710  Multimeter Probe 

Note: In addition to the Testing and Adjusting, "Tilt or Lift Cylinder Sensor Test", the VIMS diagnostics are helpful in troubleshooting sensors.

Use the “Lift or Tilt Cylinder Sensor - Test” to troubleshoot any fault that is associated with tilt cylinders and lift cylinders.

Troubleshoot sensor circuits in the following order.

  1. Perform the Testing and Adjusting, "Lift or Tilt Clyinder Pressure Sensor Signal Voltage Test". This test checks for sensor voltages at the sensor, when all the circuits are connected. DISCONNECT NOTHING. Troubleshoot 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.

  2. Perform the Testing and Adjusting, "Lift or Tilt Cylinder Sensor Dynamic Test", if necessary.

  3. The VIMS interface module is the cause of the fault if the sensor and the harness are correct. Replace the VIMS interface module. Refer to the Testing and Adjusting, "Module-Replace"section.

Lift or Tilt Cylinder Sensor Signal Voltage - Test

Note: This procedure is performed while the VIMS interface module is connected to the sensor.

Procedure

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 START THE ENGINE.

  1. CHECK THE SENSOR POWER.

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

    2. Insert the 7X-1710 Multimeter Probe leads into the back of the sensor connector between the +V and the ground circuit wire.

    3. Measure the system voltage.

      Expected Result: The voltage is between 18 and 32 DCV.

      Results:

      • OK - Voltage is between 18 and 32 DCV. The system voltage is present. Proceed to Step 2.

      • NOT OK - Voltage is not between 18 and 32 DCV. There is an open circuit. Trace the +V and ground circuits in the machine harness. Repair the machine harness or replace the machine harness. Repair the charging system of the machine. STOP.

  2. CHECK THE 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 connector along side of the signal and ground circuit wires.

    3. Measure the signal voltage and record the signal voltage.

      Expected Result: The signal voltage is approximately 5.0 DCV.

      Results:

      • VOLTAGE is 5.0 DCV. The signal voltage is approximately 5.0 DCV. The signal voltage at the sensor is correct. Proceed to Step 3.

      • VOLTAGE is GREATER THAN 6.0 DCV. The voltage is greater than 6.0 DCV. The signal voltage is not correct. Proceed to Step 4.

      • VOLTAGE is LESS THAN 1.0 DCV. The voltage is less than 1.0 DCV. Proceed to Step 2.

  3. CHECK THE SIGNAL CIRCUIT OF THE MACHINE HARNESS.

    1. At the machine harness connector for the VIMS interface module, identify the signal and ground circuits. DO NOT DISCONNECT THE HARNESS CONNECTOR.

    2. Insert the 7X-1710 Multimeter Probe leads in the back of the machine harness connector along side of the signal and ground circuit wires.

    3. Measure the signal voltage.

    4. Compare this measurement with the voltage that was recorded in Step 2. CHECK THE SIGNAL VOLTAGE.

      Expected Result: The signal voltage is equal to the voltage that was recorded in Step 2.

      Results:

      • OK - Signal voltage is equal to the voltage that was recorded in Step 2. The VIMS interface module is receiving a valid signal voltage. Proceed to Step 10.

      • NOT OK - Signal voltage is NOT equal to the voltage that was recorded in Step 2. The machine harness has an open in the signal or ground circuits. Repair the machine harness or replace the machine harness. STOP.

  4. CHECK THE MACHINE HARNESS.

    1. Signal voltage is greater than 6.0 DCV. The probable cause is a short to +battery in the machine harness or the sensor could be the cause.

    2. Disconnect the machine harness connector for the sensor.

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

      Expected Result: The voltage that is measured is less than 0.5 DCV.

      Results:

      • OK - Voltage is less than 0.5 DCV. The voltage is correct for a good harness. The sensor has failed. Replace the sensor. STOP.

      • NOT OK - Voltage is greater than 0.5 DCV. The voltage is not correct. The signal circuit of the machine harness is shorted to the +battery circuit. Repair the machine harness or replace the machine harness. If the machine harness is not the cause, replace the VIMS interface module. STOP.

  5. CHECK THE VOLTAGE OF THE SIGNAL CIRCUIT.

    1. Signal voltage is less than 1.0 DCV. The probable cause of this fault is a short to ground in the machine harness, the sensor or the VIMS interface module. Disconnect the machine harness from the sensor.

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

      Expected Result: The voltage is less than 0.5 DCV.

      Results:

      • OK - Voltage is less than 0.5 DCV. The voltage is correct. Proceed to Step 6.

      • NOT OK - Voltage is greater than 0.5 DCV. Disconnect the VIMS interface module. Recheck the voltage measurement. If the voltage is less than 0.5 DCV, replace the VIMS interface module. If the voltage is greater than 0.5 DCV, repair the machine harness or replace the machine harness. STOP.

  6. CHECK THE RESISTANCE OF THE SIGNAL CIRCUIT.

    1. Disconnect the sensor. At the machine harness connector for the sensor, measure the resistance between the signal contact and the ground contact.

      Expected Results: The resistance is approximately 47 K ohms.

      Results:

      • OK - Resistance is approximately 47 K ohms. The resistance is correct. The sensor has failed. Replace the sensor. STOP.

      • NOT OK - Resistance is less than 30 K ohms or the resistance is greater than 50 K ohms. The resistance is not correct. The machine harness or the VIMS interface module have failed. Proceed to 7.

  7. CHECK THE HARNESS.

    1. Disconnect the VIMS interface module from the machine harness.

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

      Expected Results: The resistance is greater than 100 K ohms.

      Results:

      • OK - Resistance is greater than 100 K ohms. The resistance is correct. Proceed to Step 8.

      • NOT OK - Resistance is less than 30 K ohms. The resistance is not correct. There is a short in the machine harness from ground to the sensor signal circuit. Repair the machine harness or replace the machine harness.

  8. CHECK THE HARNESS.

    1. Check continuity of harness. Place a jumper wire at the machine harness connector of the VIMS interface module between contact 2 and the sensor signal wire that is being tested.

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

      Expected Results: The resistance is less than 5 ohms.

      Results:

      • OK - Resistance is less than 5 ohms . The harness resistance is correct. The VIMS interface module has failed. Replace the VIMS interface module. STOP.

      • NOT OK - Resistance is greater than 5 ohms. The harness has failed. There is an open in the sensor signal circuit or the ground circuit of the machine harness. Repair the machine harness or replace the machine harness. STOP.

  9. CHECK THE SIGNAL CIRCUIT. VOLTAGE

    1. Disconnect the VIMS interface module 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 0.5 DCV.

      Results:

      • OK - Voltage is less than 0.5 DCV. The voltage is correct. The VIMS interface module has failed. Replace the VIMS interface module. STOP.

      • NOT OK - Voltage is greater than 0.5 DCV. there is a short in the machine harness from +battery to the sensor signal circuit. Repair the machine harness or replace the machine harness. STOP.

  10. CHECK THE FREQUENCY OF THE SENSOR.

    1. At the machine harness connector for the VIMS interface module, identify the signal and ground circuits. DO NOT DISCONNECT THE HARNESS CONNECTOR.

    2. Insert the 7X-1710 Multimeter Probe leads in the back of the machine harness connector along side of the signal and ground circuit wires.

    3. Measure the frequency of the signal.

      Expected Results: The frequency is between 150 and 2500 Hz.

      Results:

      • OK - Frequency is between 150 and 2500 Hz. The frequency is valid. The VIMS is receiving a good signal. If the problem still persists, further testing is required. Refer to the Testing and Adjusting, "Lift or Tilt Cylinder Sensor Dynamic Test".

      • NOT OK - Frequency is NOT between 150 Hz and 2500 Hz. The sensor frequency is out of range. Replace the sensor. STOP.

Lift or Tilt Cylinder Sensor Dynamic - Test

Note: This procedure is performed while the signal wire is disconnected from the VIMS interface module.

This quick check is used to determine if the sensor is functioning. The accuracy of the sensor is not checked. Perform this test only after successfully completing the Testing and Adjusting, "Lift or Tilt Cylinder Sensor Dynamic Test".

The Electrical System Schematic can be used to determine the connector contacts that correspond to a failed machine condition. Use the proper service tools to remove the connector contact of the signal wire from the machine harness connector of the VIMS interface module.

Two items are checked in this test:

  • A sensor signal is present at the VIMS interface module.

  • The signal voltage increases with a corresponding increase in the monitored system. The signal voltage decreases with a corresponding decrease in the monitored system.

Procedure

  1. CHECK THE FREQUENCY OF THE SIGNAL. .

    1. Ensure that the key start switch is in the OFF position and that the sensor is connected to the machine harness.

    2. Insert the 7X-1710 Multimeter Probeleads in the back of the machine harness connector along side of the signal and ground circuit wires.

    3. Turn the key start switch to the ON position. DO NOT START THE ENGINE.

    4. Measure the frequency between the signal contact and the ground contact. Record the frequency.

      Expected Result: The frequency is between 150 Hz and 2500 Hz.

      Results:

      • OK - Frequency is between 150 Hz and 2500 Hz. The frequency is correct. The VIMS is receiving a valid signal. If the problem still persists further testing is required. Proceed to Step 2.

      • NOT OK - Frequency is NOT between 150 Hz and 2500 Hz. The frequency is not correct. The sensor is out of range. Replace the sensor. STOP.

  2. CHANGE THE LIFT OR TILT CYLINDER PRESSURE.

    1. Load the bucket in order to increase the cylinder pressure. Proceed to Step 3.

  3. CHECK THE FREQUENCY OF THE SIGNAL.

    1. At the machine harness connector for the VIMS interface module, measure the frequency between the signal contact and the ground contact.

      Expected Result: The frequency is greater than the value that was recorded in Step 1.

      Note: The frequency should increment smoothly. The difference between the frequencies of this test CHECK THE FREQUENCY OF THE SIGNAL and the previous step CHECK THE FREQUENCY OF THE SIGNAL depend on the amount of change that is introduced into the system.

      Results:

      • OK - Frequency is greater. The frequency incremented smoothly. The sensor is not the cause. STOP.

      • NOT OK - Frequency is NOT greater. The probable cause is a failed sensor. Replace the sensor. STOP.

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