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Checking hydraulic pressure

Checking hydraulic pressure


The hydraulic pressure can be tested by measuring the system pressure in the D and R positions in the idling and stalling modes. The test will reveal the condition of the transmission.


1. Put chocks under all 4 wheels.

2. Apply the handbrake fully.

3. Remove the test plug (for B5) on the transmission housing and connect an oil pressure gauge.

4. Press the brake pedal down hard.


5. Start the engine and check the idling speed (825 rpm).

6. Depress the foot brake fully and place the selector lever in positions D and R respectively and check the system pressure according to the table.

Position

Idling

Stalling speed

D

3.4-3.9 bar

13.1-14.2bar

R

5.1 - 6.2 bar

17.4 - 20.2 bar



Important

Do not run for longer than 5 seconds when testing as the oil temperature can rise above the permitted level. Wait at least 1 minute between tests.


Check that no leakage occurs when the oil pressure gauge is connected.

Result of the hydraulic test

Cause of fault

Higher pressure than shown above in both "D" and "R"

- Fault in solenoid SLT

- Fault in the voltage supply to the valves

Lower pressure than shown above in both "D" and "R"

- Fault in solenoid SLT

- Fault in the voltage supply to the valves

- Fault in the transmission fluid pump

- Fault in brake B5

- oil leak in the "D" or "R" hydraulic circuits

Lower pressure than shown above only in "D"

- too low system pressure

- Fault in clutch C1

Lower pressure than shown above only in "R"

- Fault in the "R" hydraulic circuit

- Fault in clutch C2

- Fault in brake B3