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Home >> Volvo >> 2006 >> S80 AWD L5-2.5L Turbo VIN 59 B5254T2 >> Repair and Diagnosis >> Transmission and Drivetrain >> Differential Assembly >> Differential Lock >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Checking Four Wheel Drive

Checking Four Wheel Drive






Checking four wheel drive

Function check

Caution! Carry out the test with the vehicle raised so that all four wheels can rotate freely with the mounting at the ends of the control arms to prevent damage to the drive shafts.

Warning! Ensure that the vehicle is safely raised. Check that no objects are caught in the tire treads.

Note! If the vehicle 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. If the vehicle is equipped with TRACS (traction control system) the function must be deactivated. This is carried out by removing the fuse for the ABS modulator in the engine compartment fusebox. Note that diagnostic trouble codes (DTCs) will be stored in the brake control module (BCM). These must be erased before returning the vehicle to the customer.

- Ignition off
- Raise the vehicle so that all the driven wheels are clear of the ground
- Depress the brake pedal
- Move the gear selector to position P
- Start the engine and release the parking brake
- Move the gear selector to position D
- Release the brake pedal when the vehicle is idling. If at least one wheel on each axle rotates, the Active on Demand Coupling is verified as being active and the feed pump for the Active on Demand Coupling is functioning. Note any faulty function. 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. Note any faulty function
- Depress the accelerator pedal (AP) and maintain a speed of approximately 60-80 km/h. Check that 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 abruptly and that the front wheels continue to rotate. If this is the case the quick release in the control valve functions. Note any faulty function. If all wheels stop immediately when the parking brake is applied, valve control is not functioning. This may be caused by a function fault in the Active on Demand Coupling. Note any faulty function
- Release the parking brake and depress the brake pedal. All wheels must stop
- Move the gear selector to position D
- Release the brake pedal.

Continue - Function check

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Function check

Caution! Carry out the test with the vehicle raised so that all four wheels can rotate freely with the mounting at the ends of the control arms to prevent damage to the drive shafts.

Warning! Ensure that the vehicle is safely raised. Check that no objects are caught in the tire treads.

Note! STC (stability and traction control)/DSTC (dynamic stability and traction control) function is deactivated.

- Ignition off
- Raise the vehicle so that all the driven wheels are clear of the ground
- Depress the brake pedal
- Move the gear selector to position P
- Start the engine with the parking brake applied. The indicator lamp in the combined instrument panel must light
- Move the gear selector to position D
- Release the brake pedal when the vehicle 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 are stationary, the oil level is correct and the previous test was carried out without faults, replace the differential electronic module (DEM).

Other information:
- Differential electronic module (DEM), replacing, B5254T2, AW50/51 AWD Differential Electronic Module (DEM), Replacing
- Test driving Active on Demand Coupling, automatic transmission, AW50/51 AWD Initial Inspection and Diagnostic Overview

Was the function OK?

Yes - Function check

No - FAULT FOUND

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Function check

Caution! Carry out the test with the vehicle raised so that all four wheels can rotate freely with the mounting at the ends of the control arms to prevent damage to the drive shafts.

Warning! Ensure that the vehicle is safely raised. Check that no objects are caught in the tire treads.

Note! STC (stability and traction control)/DSTC (dynamic stability and traction control) function is deactivated.

- Ignition off
- Raise the vehicle so that all the driven wheels are clear of the ground
- Move the gear selector to the N position
- Start the engine with the parking brake applied
- Allow the engine to idle and at the same time attempt to pull round both front wheels.

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.

- Disconnect the 2-pin connector between the differential electronic module (DEM) and the feed pump
- 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 between the differential electronic module (DEM) and the feed pump
- The build up of basic pressure in the clutch can be felt when the front wheels brake via the Active on Demand Coupling
- Disconnect the 8-pin connector between the differential electronic module (DEM) and the cable from the vehicle.

Note! When the power supply to the differential electronic module (DEM) is cut, the choke valve quickly opens. This is verified by the basic torque ceasing immediately.

- Connect the connector for the differential electronic module (DEM)
- Note that the feed pump for the Active on Demand Coupling starts. On Start-up 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 feed pump for the Active on Demand Coupling must not rotate in this position.
If the basic pressure function of the Active on Demand Coupling and the function of the feed pump for the Active on Demand Coupling are verified and the test is OK, replace the Active on Demand Coupling.
If the basic pressure function of the Active on Demand Coupling and the function of the feed pump for the Active on Demand Coupling are verified and the test is not OK, replace the differential electronic module (DEM).

Other information
- Clutch (AOC), replacing, B5254T2, AW50/51 AWD Clutch (AOC), Replacing
- Differential electronic module (DEM), replacing, B5254T2, AW50/51 AWD Differential Electronic Module (DEM), Replacing
- Test driving Active on Demand Coupling, automatic transmission, AW50/51 AWD Initial Inspection and Diagnostic Overview

Was a fault detected?

Yes - FAULT FOUND

No - No Fault Found

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