992G Wheel Loader Electrohydraulic System Caterpillar

This test is an easy method and an accurate method of measuring the drift on the lift linkage and the drift on the tilt linkage. There are two modes for the measurement of drift rate. In these tests, cylinder drift is determined by comparing the change in the cylinder movement to a specified time.

Prepare the machine for the testing.

1. Park the machine on a smooth, level surface. The area must be clear so that the bucket can be fully raised and lowered.

2. The bucket must be empty.

3. The parking brake must be engaged.

4. The transmission should be in neutral.

5. The hydraulic oil must be between 62 °C (143 °F) and 68 °C (154 °F).

The machine should be ready for the drift tests. Follow the steps in order to set up the VIMS module.

Drift Check for the Lift Linkage

Show/hide table



Illustration 1	g00284487
Right Console (1) Keypad.

Show/hide table



Illustration 2	g00286975
Front Dash (2) Diagnostic message screen.

1. Press the "OK" key on keypad (1) repeatedly. The hour meter will appear on diagnostic message screen (2) . Press the "OK" key on keypad (1) repeatedly until the hour meter appears on diagnostic message screen (2) .

2. On the keypad, enter "SERV (7378)" and then press "OK". Press the ">" key until the diagnostic message screen registers "LIFT CYL DRIFT - CHECK". The first test will calculate the drift for the lift linkage. This test will calculate the drift for the tilt linkage.
   Show/hide table

   Table 1

   "SELECT CALIBRATION" "LIFT CYL DRIFT - CHK"

3. The lift linkage is ready to check for drift through the VIMS module. When you are ready to start the test press the "OK" key.
   Show/hide table

   Table 2

   "LIFT CYL DRIFT - CK" "PRESS [OK] TO START"

4. In this step, the parking brake must be engaged. If the parking brake is already engaged, the calibration will proceed to the next step. If the drift check has failed, proceed to Step 14.
   Show/hide table

   Table 3

   "PARKING BRAKE" "MUST BE SET"

5. In this step, the transmission must be in neutral. If the transmission is in neutral, the test will proceed to the next step.
   Show/hide table

   Table 4

   "TRANSMISSION MUST" "BE IN NEUTRAL"

6. In this step, the hydraulic oil must be at the temperature between 62 °C (143 °F) and 68 °C (154 °F). If the hydraulic oil is already at the temperature, the calibration will proceed to the next step.
   Show/hide table

   Table 5

   "WARM HYD OIL TO" "(60-70) XXX °C"

7. In this step, raise and lower the lift linkage five times. Then, press the "OK" key.
   Show/hide table

   Table 6

   "EXT LIFT CYL 5 TIMES" "THEN PRESS [OK]"

8. Move the lift linkage to the full RAISE position. Then press the "OK" key.
   Show/hide table

   Table 7

   "RAISE BOOM FULLY" "THEN PRESS [OK]"

9. Then release the lift control lever.
   Show/hide table

   Table 8

   "RELEASE LEVER"

10. The lift control lever is released. At this time, the VIMS module is calculating the drift for the lift linkage.
    Show/hide table

    Table 9

    "CHECKING CYL DRIFT" "XXX SEC REMAINING"

11. The drift test has passed. The amount of drift for the lift linkage is within the specification. The screen will display "RESULTS OK". Proceed to the next step. If the measurement of the drift rate has exceeded the specification, proceed to Step 15.
    Show/hide table

    Table 10

    "RESULTS OK"

12. In three seconds, the screen will display "CYL DRIFT OK". Then, display the actual amount of drift. Then, the screen will display the actual drift of the lift linkage.
    Show/hide table

    Table 11

    "CYL DRIFT OK" "(<100) XXX MM"

13. Press the "OK" key in order to acknowledge the measurement of the drift rate. Then proceed to Step 16.
    Show/hide table

    Table 12

    "PRESS OK" "TO ACKNOWLEDGE"

14. If a failure occurs, press the ">" key for the reason.
    Show/hide table

    Table 13

    "DRIFT CHECK FAILED" "PRESS [>] FOR REASON"

    1. If the display shows "LIFT LINKAGE SNSR ERR", the problem is with the sensor circuit. The lift linkage position sensor has one of the following conditions. no signal, wrong frequency, out of calibration and wiring problem. The problem must be repaired before the calibration can be completed. The display will advance. Then, press the "OK" key in order to acknowledge the error. Then, the procedure will proceed to Step 16.
       Show/hide table

       Table 14

       "LIFT LINK SNSR ERR" "CHECK SNSR/CAL/WIRING"

       Show/hide table

       Table 15

       "PRESS [OK]" "TO ACKNOWLEDGE"

15. If the measurement of the drift rate for the lift linkage has exceeded the maximum allowable drift, the test has failed. Press the ">" key for the reason.
    Show/hide table

    Table 16

    "DRIFT CHECK FAILED" "PRESS [>] FOR REASON"

    1. If the display shows "LIFT LINKAGE SNSR ERR", the problem is with the sensor circuit. The lift linkage position sensor has one of the following conditions. no signal, wrong frequency, out of calibration and wiring problem. The problem must be repaired before the calibration can be completed. The display will advance. Then, press the "OK" key in order to acknowledge the error. Then, the procedure will proceed to Step 16.
       Show/hide table

       Table 17

       "LIFT LINK SNSR ERR" "CHECK SNSR/CAL/WIRING"

       Show/hide table

       Table 18

       "PRESS [OK]" "TO ACKNOWLEDGE"

    2. In this step, the measurement of the drift rate is out of the specification. The screen will display the exact amount of drift in the lift linkage. Then, press the "OK" key in order to acknowledge the rate of drift. Then, the procedure will proceed to Step 16.
       Show/hide table

       Table 19

       "LIFT CYL DRIFT HIGH" "(>100) XXX MM"

       Show/hide table

       Table 20

       "PRESS [OK]" "TO ACKNOWLEDGE"

16. The program is exiting the service mode. The test has been completed.
    Show/hide table

    Table 21

    "EXITING " "SERVICE MODE"

Drift Check for the Tilt Linkage

Show/hide table



Illustration 3	g00284487

Show/hide table



Illustration 4	g00286975

1. Press the "OK" key on keypad (1) repeatedly. The hour meter will appear on diagnostic message screen (2) . Press the "OK" key on keypad (1) repeatedly until the hour meter appears on diagnostic message screen (2) .

2. On the keypad, enter "SERV (7378)" and then press "OK". Press the ">" key until the diagnostic message screen registers "TILT CYL DRIFT - CHECK". This test will calculate the drift for the tilt linkage.
   Show/hide table

   Table 22

   "SELECT CALIBRATION" "TILT CYL DRIFT - CHECK"

3. The tilt linkage is ready to check for drift through the VIMS module. When you are ready to start the test press the "OK" key.
   Show/hide table

   Table 23

   "TILT CYL DRIFT -CK" "PRESS [OK] TO START"

4. In this step, the parking brake must be engaged. If the parking brake is already engaged, the test will proceed to the next step. If the drift check has failed, proceed to Step 14.
   Show/hide table

   Table 24

   "PARKING BRAKE" "MUST BE SET"

5. In this step, the transmission must be in neutral. If the transmission is already in neutral, the test will proceed to the next step.
   Show/hide table

   Table 25

   "TRANSMISSION MUST" "BE IN NEUTRAL"

6. In this step, the hydraulic oil must be at the temperature between 62 °C (143 °F) and 68 °C (154 °F). If the hydraulic oil is already at the temperature, the test will proceed to the next step.
   Show/hide table

   Table 26

   "WARM HYD OIL TO" "(60-70) XXX °C"

7. In this step, extend the tilt linkage and retract the tilt linkage five times. Then, press the "OK" key.
   Show/hide table

   Table 27

   "EXT TILT CYL 5 TIMES" "THEN PRESS [OK]"

8. Level the bucket. Then, press the "OK" key.
   Show/hide table

   Table 28

   "LEVEL BUCKET" "THEN PRESS [OK]"

9. Release the tilt control lever.
   Show/hide table

   Table 29

   "RELEASE LEVER"

10. The lift control lever is released. At this time, the VIMS module begins to check the measurement of the drift rate for the lift linkage.
    Show/hide table

    Table 30

    "CHECKING CYL DRIFT" "XXX SEC REMAINING"

11. The drift test has passed. The amount of drift for the tilt linkage is within the specification. The screen will display "RESULTS OK". Proceed to the next step. If the measurement of the drift rate has exceeded the specification, proceed to Step 15.
    Show/hide table

    Table 31

    "RESULTS OK"

12. In three seconds, the screen will display "CYL DRIFT OK". Then, the screen will display the actual drift of the tilt linkage.
    Show/hide table

    Table 32

    "CYL DRIFT OK" "(<100) XXX MM"

13. Press the "OK" key in order to acknowledge the measurement of the drift rate. Then, proceed to Step 16.
    Show/hide table

    Table 33

    "PRESS OK" "TO ACKNOWLEDGE"

14. If a failure occurs, press the ">" key for the reason.
    Show/hide table

    Table 34

    "DRIFT CHECK FAILED" "PRESS [>] FOR REASON"

    1. If the screen will display "TILT LINKAGE SNSR ERR", the problem is with the sensor circuit. The tilt linkage position sensor has one of the following conditions. no signal, wrong frequency, out of calibration and wiring problem. The problem must be repaired before the calibration can be completed. The display will advance. Then, press the "OK" key in order to acknowledge the error.
       Show/hide table

       Table 35

       "TILT LINK SNSR ERR" "CHECK SNSR/CAL/WIRING"

15. If a failure occurs in the drift check, press the ">" key for the reason.
    Show/hide table

    Table 36

    "DRIFT CHECK FAILED" "PRESS [>] FOR REASON"

    1. If the screen will display "TILT LINKAGE SNSR ERR", the problem is with the sensor circuit. The tilt linkage position sensor has one of the following conditions. no signal, wrong frequency, out of calibration and wiring problem. The problem must be repaired before the calibration can be completed. The display will advance. Then, press the "OK" key in order to acknowledge the error.
       Show/hide table

       Table 37

       "TILT LINK SNSR ERR" "CHECK SNSR/CAL/WIRING"

    2. Press the "OK" key in order to acknowledge the error. Then, the procedure will proceed to Step 16.
       Show/hide table

       Table 38

       "PRESS [OK]" "TO ACKNOWLEDGE"

    3. In this step, the measurement of the drift rate is out of the specification. The screen will display the exact amount of drift in the tilt linkage. Then, press the "OK" key in order to acknowledge the rate of drift. Then, the procedure will proceed to Step 16.
       Show/hide table

       Table 39

       "TILT CYL DRIFT HIGH" "(>100) XXX MM"

       Show/hide table

       Table 40

       "PRESS [OK]" "TO ACKNOWLEDGE"

16. The program is exiting the service mode.
    Show/hide table

    Table 41

    "EXITING " "SERVICE MODE"