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Testing cruise control system (CCS) > < Testing clutch pedal switch

A3 Mk1

Diesel Direct Injection and Glow Plug System (TDI 4 cyl.) >07.99
Checking auxiliary signals
Checking vehicle speed signal

The speed signal is required for shutting off the air conditioner compressor when accelerating, for the cruise control system and to ensure smoother driving (jolt damping).

Test conditions

  • ● Speedometer OK, checking:

=> Electrical System; Repair group 90

  • ‒ Read measured value block, display group 06, engine at idling speed
 
→ Indicated on display:
Read measured value block 6    ⇒
    0 km/h    255    0    0    000000    0
Important:
Second person is required to operate V.A.G 1551.
  • ‒ Perform a road test.
  • ‒ Observe readout in display zone 1.
 
→ Specification: The current road speed should be displayed (compare with speedometer).
Read measured value block 6    ⇒
    45 km/h    255    0    0    000000    0

If specified value is not attained:

  • ‒ Connect test box V.A.G 1598/22 to wiring harness for engine control unit .

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

Test box V.A.G 1598/22, socket

Dash panel insert, contact

51

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations
  • ‒ Rectify any open/short circuit as necessary.

If no wiring fault is detected:

  • ‒ Find all the speed signal "consumers" (e.g. radio, automatic gearbox, air conditioner etc.), disconnect them one by one from the dash panel insert, then repeating the test until the cause of the problem has been identified.

Testing cruise control system (CCS) > < Testing clutch pedal switch