With Manufacturer's Scan Tool

Vehicle Speed Signal, Checking

Speed signal is required for air conditioner compressor cut-off when accelerating, for cruise control system and to improve driving comfort (jerk damping).

Special tools and equipment
- Scan Tool (ST) VAG 1551/1552 with cable VAG 1551/3
- VAG 1598/22 test box (through my 1999)
- VAG 1598/31 test box (from my 2000)
- VAG 1594 adapter kit
- VAG 1527 electrical tester
- Wiring diagram

Test conditions
- Battery 11.5 volts minimum.
- Speedometer must be OK., checking speedometer:

Test sequence

NOTE: Test and measuring equipment must be secured to rear seat and operated by a 2nd person.

WARNING!
If test and measuring equipment is operated from the front seat and vehicle is involved in an accident, there is a possibility the person may be injured when the airbag is deployed. Secure Scan Tool (ST) to rear seat.

- Connect Scan Tool V.A.G 1551/1552, refer to "On Board Diagnostic II/VAG 1551/VAS 5051 Scan Tool, Testing and Inspection
- Start engine and let idle
- Press -0- and -1 - to select Address word 01: "Engine electronics"

Indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- for "Read measured value block" and confirm with -Q- button.

Indicated on display:

Read measured value block HELP
Input display group number XXX

- Press buttons -0-, -0- and -6- for "Display group number 6" and confirm with -Q- button.
- Test drive with 2nd person to observe display.

Observe safety precautions when driving road test [1][2]Technician Safety Information

- Observe figure in display field 1.

Read measured value block 6 ->
XXX km/h 0 0 0 000000 255

Specification: approx. road speed

- Press -> button.
- Press buttons -0- and -6- for "End output" and confirm with -Q- button.
- Switch off ignition.

If no speed is indicated:
- Remove wiper arms and cowl panel






- Connect VAG 1598/22 (through my 1999) or VAG 1598/31 (from my 2000) test box to Engine Control Module (ECM) -J248- wiring harness.
- Connect electrical tester between following sockets:
- Through MY 1999: 1 (ground) and socket 51 (speed signal)
- From MY 2000: 4 (ground) and socket 20 (speed signal)
- Lift vehicle at front left.
- Switch on ignition.
- Rotate front wheel and observe LED in electrical tester.

LED must flash
(approx. four times per wheel rotation).

NOTE: If necessary, hold front right wheel to prevent it from turning.

- If diode test lamp does not flash, check wiring from following terminal of Engine Control Module (ECM) -J248- connector, to instrument cluster for open/short circuit:
- Through MY 1999: 51
- From MY 2000: 20

- Check DTC memory, if necessary, repair any malfunctions and erase DTC memory, refer to "Diagnostic Trouble Code (DTC) Memory, Checking and Erasing" Testing and Inspection
- Display readiness code.

If DTC memory has been erased or Engine Control Module (ECM) -J248- was disconnected:
- Readiness code must be reset.