Testing vehicle speed signal — AUDI

ADW
Special tools, testers and auxiliary equipment required

Hand-held multimeter V.A.G 1526 or V.A.G 1526 A
Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with wire V.A.G 1551/1
Adapter set V.A.G 1594 A
Test box V.A.G 1598/18

Test requirements:

Speedometer OK, checking:

=> Electrical system; Repair group 90; Testing dash panel insert components; Testing road speed signal sender
Electrical system
Testing dash panel insert components
Testing road speed signal sender

Connect fault reader V.A.G 1551 and select engine electronics control unit => Page
01-2.
Read measurement block 4
⇒ (1) (2) (3) (4)
Read measured value block, display group 004 => Page
01-68.

Notes:

A second operator is required to note readings with the vehicle moving.
Observe safety precautions => Page
24-1

Take the vehicle for a test drive.

Note:

What is displayed in display zone 3 is not the road speed but a road speed signal.

Test the readout in display zone 3 when starting off.
Specification when stationary: 255
Specification when driving: 0

Press the ⇒key.

Rapid data transfer
HELP
Select function XX
Indicated on display:

Enter "06" for "End output" function and confirm entry with Q key.

If the readout does not change at the transition from stationary to driving:

With the ignition switched off, connect test box V.A.G 1598/18 to connector for engine control unit => Page
24-16.

Test the wiring connection between contact 11 of the connector of the Digifant control unit and the dash panel insert for open circuit or short circuit according to the current flow diagram.
Rectify any open/short circuit as necessary. "Testing road speed signal"
If the wiring connection is OK continue fault finding with the fault finding programme "Testing road speed signal".

=> "Current Flow Diagrams, Electrical Fault Finding and Fitting Locations" binder

If you have not found any fault so far on the basis of the fault finding programme "Testing road speed signal", replace the Digifant control unit => Page
24-18.

Notes:

After replacing the Digifant control unit , it is necessary to adapt the control unit and throttle valve potentiometer to each other => Page
24-92.
After replacing the Digifant control unit on vehicles fitted with an automatic gearbox, it is necessary to adapt the automatic gearbox control unit and the throttle valve potentiometer to each other => Page
24-93.