Speed Signal, Checking

Speed signal, checking

Special tools and equipment
- V.A.G 1551 scan tool (or VAG1552 mobile scan tool) with VAG 1551/3B cable
- VAG 1598/31 adapter cable
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test requirements
- Battery voltage must be at least 11.5 volts.
- Speedometer must be OK. Checking speedometer.

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 V.A.G 1551 scan tool (VAG 1552). Start engine and select the Engine Control Module (ECM) using address word 01.(connecting scan tool and selecting ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551 Scan Tool", Connecting VAG 1551 Scan Tool

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 HELP
Enter display group number XXX


- Press buttons -0-, -0- and -5- to select "Display group number 5". Press -Q- button to confirm input.

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.
- Read value indicated in display field 3. Specification: approx. vehicle speed
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.

If no speed is indicated:







- Connect VAG 1598/31 adapter cable to control module wiring harness. Engine Control Module (ECM) is not connected.
- To measure voltage, connect multimeter between sockets 3 (terminal 15) + 54 (speed signal) of test box.
- 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

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