Vehicle Speed Signal, Checking

VEHICLE SPEED SIGNAL, CHECKING

Special tools, testers and auxiliary items
- VAG 1551 Scan Tool (ST) or vehicle system tester VAG 1552 with VAG 1551/3 adapter cable
- Multimeter (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagram

Test conditions
- Speedometer OK

WARNING! The vehicle speed signal must be checked while driving the vehicle. To do this safely, a second person is required.

Test sequence
- Connect VAG 1551 scan tool (VAG 1552) and insert "Engine Electronics" address word 01. Carry out selection at idle. Refer to "On-Board Diagnostic". Testing and Inspection

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
Input display group number XXX

- Press -0-, -0- and -4- to input display group number 004.
- Press -Q- button to confirm input.

Indicated on display (1, 2, 3 and 4 = Display fields)

Read measuring value block ->
1 2 3 4

NOTES:
- If something different is indicated on display:
See Scan tool operating instructions.
- If an incorrect input causes "Error in communication link" to be displayed, disconnect cable from VAG 1551 scan tool, then reconnect and repeat work steps.

- Carry out test drive and, with 2nd person, observe display in display field 3.

Specification: approx. vehicle road speed

- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06.
- Press -Q- button to confirm input.

If no speed is indicated:





- Disconnect 3-pin harness connector from sensor -1-
- Switch ignition on.





- Check voltage between connector terminals 1 and 3.

Specification: Min. 9 volts

- Switch ignition off.
- Reconnect harness connector.

If no voltage was present:
- Check wiring according to wiring diagram.

If voltage was min. 9 volts:





- Connect VAG 1598/18 test box to ECM wiring harness.
- Check wire for open circuit between single connector (behind central electrics) and test box socket 65, according to wiring diagram.

Wire resistance: Max. 1.5 Ohms

- Connect multimeter to measure voltage at test box sockets 56 and 65.
- Switch ignition on.
- Raise and rotate left front wheel, or push vehicle.
- Voltage must fluctuate between 0 volts and at least 4 volts

If no wiring malfunction is detected and voltage was present between terminals 1 and 3:
- Replace speedometer vehicle speed sensor G22.