Audi Workshop Service and Repair Manuals

Notes:

• ◆ The road speed signal is produced by the road speed sender -G68 and processed in the dash panel insert.
• ◆ The processed signal goes to contact 20 on the engine control unit and is used for idling speed stabilisation and for the damping of load change jolts when changing gear.

• ‒ Connect fault reader V.A.G 1551
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• ‒ Switch ignition on.
• ‒ Read measured value block (function 08) and select Display Group 11.

• ‒ Take vehicle for a test drive and check whether the road speed appears in display zone 3.
• ‒ If the road speed is not displayed, lift vehicle at the front left until the wheel is off the ground.

• ‒ → Connect test box V.A.G 1598/22 to wiring harness for engine control unit.
  .
• ‒ Connect diode test lamp between socket 3 (positive) and socket 20 (signal).
• ‒ Switch on the ignition and turn the front left wheel by hand.
• ‒ The diode test lamp should flash (very brief flashes).

Note:

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

• ‒ If the diode test lamp does not flash, test for open circuit and short circuit in wiring between dash panel insert and contact 20 on connector for engine control unit.

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