Vehicle Speed Sensor: Testing and Inspection

Speed Signal, Checking

Special tools and equipment
- VAG1551 scan tool (or VAG1552 mobile scan tool) with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements







- All fuses must be OK.
- Battery voltage must be at least 11.5 volts.
- Speedometer must be OK.

Test sequence


NOTE: To test speed signal, vehicle must be driven. Doing this requires a second person.


WARNING!
Secure Scan Tool (ST) on the rear seat and have operated from there by second technician.


- Connect VAG1551 scan tool (VAG1552). Start engine and select the Engine Control Module (ECM) using address word 01.

Connecting scan tool and selecting ECM. Refer to Scan Tool Connecting and Initial Checks. Scan Tool Testing and Procedures

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display:


Read measuring value block
Enter display group number XXX


- Press 0, 0 and 5 for the function "display group number 5", and then press Q to exit from input mode.

Indicated on display: (1 to 4 = display fields)


Read measuring value block 5 ->
1 2 3 4


- Perform a road test, and have the 2nd person observe the indication on the display.

Observe the safety precautions that apply to road tests.
- Read value indicated in display field 3. Specification: approx. vehicle speed
- Display Group 5 and its evaluation
- Press the -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.

Continuation

If no speed is indicated:







- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.
- Connect multimeter between sockets 2 + 54 of test box for voltage measurement.
- Switch ignition on.
- Jack up front left wheel.
- Rotate front wheel, and observe voltage indicated while doing so. Specification: oscillating between 0 and at least 4 volts


NOTE: The right front wheel must not turn during this, hold it steady if necessary.


If indicated voltage does not oscillate:
- Check wires going to speedometer and speed sensor.