Audi Workshop Service and Repair Manuals

Checking engine speed sender -G28- Special tools and workshop equipment required t  Portable multimeter -V.A.G 1526C- t  Adapter set -V.A.G 1594C- t  121-pin adapter cable -V.A.G 1598/31- Fitting location ⇒ Overview of fitting locations → Chapter

Test sequence   Note The engine speed sender is a combined engine speed and reference mark sender. The engine cannot be started without a signal from the engine speed sender -G28-. Failure of the engine speed sender -G28- signal with the engine running causes it to cut out immediately. –  Check proper installation and attachment of the engine speed sender -G28- before performing the test.

–  Unplug connector of engine speed sender -G28--1- (identification: grey connector).

–  Connect up the multimeter (resistance measuring range) between contacts 2 and 3. t  Specification: 730 ...1000 Ω   Note The resistance value of the engine speed sender is referenced to a temperature of 20 °C. The resistance increases with increasing temperature. If the reading does not match the specification: –  Replace the engine speed sender -G28-. If the reading matches the specification:

–  Connect the multimeter (resistance measurement range) to contacts 2 and 1 (screen) as well as to contacts 3 and 1 (screen). t  Specification: ∞ Ω (no continuity) If the reading does not match the specification: –  Replace the engine speed sender -G28-. If the reading matches the specification: –  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter.

–  Check for open circuit and short to earth or positive in the following wiring:

Connector Contact	Test box -V.A.G 1598/31- Socket
1 (screen)	108
2 (earth)	90
3 (signal)	82

–  Eliminate open circuit in wiring/short circuit if necessary. If no fault is found in the wiring: –  Replace the engine control unit → Chapter.