Audi Workshop Service and Repair Manuals

Final control diagnosis The final control diagnosis can be used to check the ABS hydraulic pump -V64- and the correct functioning of the hydraulic circuits (allocation of brake pipes to wheel brakes and function of valves). This function will also detect interchanged connections and leaks.   Note t  The vehicle must be raised until all wheels are free to turn. A 2nd mechanic is required in order to turn the wheels. t  The ABS warning lamp -K47- and the red “brake warning” symbol flash during the final control diagnosis. t  After depressing the brake pedal several times the vacuum in the brake servo will be exhausted. Therefore more pressure must be applied to the brake pedal in order to attain the same fluid pressure in the brake system as that attained with vacuum. t  When vacuum in brake servo is exhausted it can happen that the wheels do not lock: start engine and build up vacuum in brake servo. Explanation of abbreviations indicated on display

IFL	=	Inlet valve (front left)
IFR	=	Inlet valve (front right)
IRL	=	Inlet valve (rear left)
IRR	=	Inlet valve (rear right)
OFL	=	Outlet valve (front left)
OFR	=	Outlet valve (front right)
ORL	=	Outlet valve (rear left)
ORR	=	Outlet valve (rear right)
VBAT	=	Battery voltage; voltage is applied to valve
0V	=	0 Volt; No voltage at valve
Hydr-P	=	ABS hydraulic pump -V64-

Test condition l  The wheels are locked individually during final control diagnosis. For this test the mechanical and hydraulic components of the brake system must be working properly. This means that the master cylinder is able to build up pressure in all four wheel brake cylinders and there are no leaks in the hydraulic pipes, hoses and connections.   Note If one of the wheels does not lock, perform a visual inspection of the brake fluid reservoir, the master cylinder, the hydraulic unit and the wheel cylinders. Procedure –  Connect vehicle diagnostic, testing and information system -VAS 5051 A- → Chapter and select vehicle system “03 - Brake electronics”. When doing this the ignition must be switched on.

Indicated on -VAS 5051 A-: –  Release handbrake. –  Raise vehicle on lifting platform. –  From list -1- select function “03 - Final control diagnosis”.

Indicated on -VAS 5051 A-: A -  Final control test waiting, move on to next control element 1 -  ABS hydraulic pump V64 –  Touch → key. Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 1 -  ABS hydraulic pump V64 l  The ABS hydraulic pump -V64- should start up audibly. –  Touch → key within the next 10 seconds.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 2 -  Operate brakes –  Operate brake pedal. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 3 -  IFL: 0V  OFL: 0V   Wheel FL locked l  It should not be possible to turn the front left wheel. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 4 -  IFL: VBAT  OFL: 0V   Wheel FL locked –  Keep pressing the brake pedal. l  The ABS hydraulic pump -V64- should start up audibly. l  Brake pedal should not give under foot pressure. l  It should not be possible to turn the front left wheel.   Note If the brake pedal gives under foot pressure, there is a fault in the hydraulic unit. Renew hydraulic unit → Brake system; Rep. Gr.45. –  Touch → key within the next 10 seconds.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 5 -  IFL: VBAT  OFL: VBAT   Wheel FL free to turn –  Keep pressing the brake pedal. l  ABS hydraulic pump -V64- will stop running. l  It should now be possible to turn the front left wheel.   Note If the wheel is locked, it is possible that the connections of the brake lines to the wheels have been interchanged by mistake. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 6 -  IFL: VBAT  OFL: 0V   Wheel FL free –  Keep pressing the brake pedal. l  The brake pedal should give perceptibly. l  It should now be possible to turn the front left wheel.   Note If the brake pedal does not give under foot pressure, there is a fault in the hydraulic unit. Renew hydraulic unit → Brake system; Rep. Gr.45. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 7 -  IFL: 0V  OFL: 0V   Wheel FL locked –  Keep pressing the brake pedal. l  It should not be possible to turn the front left wheel. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 8 -  Release brakes –  Release brake pedal. –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 9 -  Operate brakes   Note t  Continue the final control diagnosis to check the front right, rear left and rear right wheels in turn. t  The test steps are the same as for the front left wheel, so they are not described in detail. Vehicles with EDL: After testing on rear right wheel is completed: –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis running, moving on permitted 30 -  EDL valves/Hyd-P: VBAT FL/FR wheel locked l  The ABS hydraulic pump -V64- should start up. All models: –  Touch → key.

Indicated on -VAS 5051 A-: A -  Final control diagnosis competed –  Terminate function “03 - Final control diagnosis” by pressing the ← key. l  Final control diagnosis is completed. The ABS warning lamp -K47- and the red “brake warning” symbol should go out.   Note t  There is a fault in the system if the ABS warning lamp -K47- does not go out. t  Adhere exactly to the test sequence: First interrogate fault memory, then erase.