Audi Workshop Service and Repair Manuals > A3 Mk1 > Power unit | Simos injection and ignition system (4-cylinder) | Mixture preparation system, electronic inj.,Gas | Checking auxiliary signals | Checking vehicle speed signal

Test sequence

–	Connect vehicle diagnostic, testing and information system -VAS 5051- or fault reader -V.A.G 1551- and select engine electronics control unit by entering “address word ” 01. For this purpose, the engine must be running at idling speed.

Caution

To avoid accident risks when road testing the vehicle with test equipment, always observe the relevant safety precautions → Chapter.

Indicated on display:

–	Enter “08” for the function “Read measured value block” and confirm entry with the Q key.

Rapid data transfer            HELP

Select function XX

Indicated on display:

–	Enter “005” for “Display group number 005” and confirm entry with the Q key.

Reading measured value block                  Q

Enter display group number XXX

Indicated on display:

–	Take vehicle for a test drive and check whether the vehicle speed appears in display zone 3.

–	If the vehicle speed does not appear, raise the vehicle (preferably using a lifting platform) until the front left wheel is clear of the ground.

–	Connect test box -V.A.G 1598/31- to wiring harness for engine control unit. Do not connect engine control unit → Chapter.

–	Connect voltage tester -V.A.G 1527 B- to sockets 3 (positive) and 9 (vehicle speed signal) on test box-V.A.G 1598/31-.

–	Switch on ignition and turn front left wheel by hand.

t	The LED lamp should flash (very brief flashes).

If the LED does not flash:

–	Check for open circuit and short to positive or earth in the following wiring connections:

Read measured value block 5                 ->

         1         2         3         4

Test box -V.A.G 1598/31- Socket	Dash panel insert Contact
9	. → Current flow diagrams, Electrical fault finding and Fitting locations

–	Rectify any open/short circuit as necessary.

Audi Workshop Service and Repair Manuals