Checking the Four Wheel Drive For Automatic Transmissions
Checking the four wheel drive for automatic transmissions
Function of four wheel drive for automatic transmissions
Note! If the car has STC or DSTC, these functions must be disengaged. Press in the STC/DSTC button on the center console. Hold the button in for at least 2 seconds. The LED on the button must go out.
Warning! Ensure that the car is safely raised. Check that no objects are caught in the tire treads.
Caution! The test must be carried out on a car raised on a 2-post lift secured on the control arms so that the wheels can rotate freely.
- Ignition off
- Raise the car so that all the driven wheels are clear of the ground
- Depress the brake pedal
- Move the gear selector to the P-position
- Start the engine and release the parking brake
- Move the gear selector to position D
- Release the brake pedal when the car is idling.
If at least one wheel on each axle rotates the Active on Demand Coupling is verified as being active and the oil pump for the Active on Demand Coupling functioning.
If the front wheels rotate at normal speed and the rear wheels do not rotate this means that the Active on Demand Coupling function is faulty.
- Depress the accelerator pedal (AP) and maintain a speed of approximately 60-80 km/h. All wheels rotate at the same speed
- Release the accelerator pedal (AP)
- Select N immediately after releasing the accelerator pedal (AP)
- Apply the parking brake when the wheels are still rotating at 60-80 km/h.
Check that the rear wheels stop rotating immediately and that the front wheels continue to rotate while losing speed. If this is the case the quick release in the control valve functions.
If all wheels stop immediately when the parking brake is applied the control valve is not functioning. This may be caused by a function fault in the Active on Demand Coupling.
- Release the parking brake and depress the brake pedal. All wheels must stop
- Move the gear selector to position D
- Release the brake pedal.
Check that at least one wheel on each axle rotates.
Continue - Checking the four wheel drive for automatic transmissions
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Checking the four wheel drive for automatic transmissions
Note! STC (stability and traction control)/DSTC (dynamic stability and traction control) function is deactivated.
Warning! The car safely raised.
Caution! The test must be carried out on a car raised on a 2-post lift secured on the control arms so that the wheels can rotate freely.
- Ignition off
- Raise the car so that all the driven wheels are clear of the ground
- Depress the brake pedal
- Move the gear selector to the P-position
- Start the engine with the parking brake applied. Indicator lamp in the driver information module must light - signal to the differential electronic module
- Move the gear selector to position D
- Release the brake pedal when the car is idling.
If the front wheels rotate slowly and the rear wheels do not rotate the Active on Demand Coupling is OK.
If the front wheels rotate at normal speed, the rear wheels do not rotate, the oil level is correct and test 1 (previous test) was carried out without faults, the function of the feed pump is OK but the function of the control valve is faulty. To replace the Active on Demand Coupling control module see Replacing the oil filter for the Active on Demand Coupling Replacing the Oil Filter For the Active On Demand Coupling.
Has the fault been remedied?
Yes - Fault Found
No - Checking the four wheel drive for automatic transmissions
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Checking the four wheel drive for automatic transmissions
Note! STC (stability and traction control)/DSTC (dynamic stability and traction control) function is deactivated.
Warning! The car safely raised.
Caution! The test must be carried out on a car raised on a 4-post lift secured on the control arms so that the wheels can rotate freely.
- Ignition off
- Raise the car so that all the driven wheels are clear of the ground
- Move the gear selector to position N
- Start the engine with the parking brake applied
- Let the engine idle.
Attempt to rotate both front wheels at the same time from underneath the car.
Note! The basic function of the Active on Demand Coupling and the function of the oil pump for the Active on Demand Coupling can be verified by checking to see if the brake force on the rear wheels also brakes the front wheels.
- Remove the two pin connector from the oil pump for the differential electronic module
- When the basic pressure drops, the successive reduction in basic pressure can be deduced by the reduction and ceasing of the basic torque
- Connect the connector to the oil pump for the Active on Demand Coupling
- The build up of basic pressure in the clutch can be felt when the front wheels brake via the Active on Demand Coupling
- Remove the eight pin connector between the differential electronic module and the cable from the car
Note! When the power supply to the differential electronic module is cut the choke valve quickly opens. This is verified by the basic torque ceasing immediately.
- Connect the connector to the differential electronic module
- Note that the oil pump for the Active on Demand Coupling starts. On Startup an increase in speed of the pump can be heard
- Switch off the engine and leave the ignition on
- Leave the parking brake applied and the gear selector in position N
- The oil pump for the Active on Demand Coupling must not rotate in this position.
If the basic function of the Active on Demand Coupling and the function of the oil pump for the Active on Demand Coupling are verified and the test is OK, replace the Active on Demand Coupling. See Active on Demand Coupling (AOC), replacing Active On Demand Coupling (AOC), Replacing.
If the basic function of the Active on Demand Coupling and the function of the oil pump for the Active on Demand Coupling are verified and the test isnotOK, replace the Active on Demand Coupling control module. See Replacing the oil filter for the Active on Demand Coupling Replacing the Oil Filter For the Active On Demand Coupling.
Was a fault detected?
Yes - Fault Found
No - No Fault Found
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