Volkswagen Workshop Service and Repair Manuals

The engine speed sender (G28) is a speed and reference mark sender. If the speed signal fails when the engine is running, it can cause the engine to stall.

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Test box V.A.G 1598/31
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test conditions

• ● The battery voltage must be at least 11.5 V.

Test sequence

• ‒ → Detach black 3-pin connector to engine speed sender -arrow- (on thermostat housing).

• ‒ → Connect multimeter to measure voltage using aux. cables from V.A.G 1594 to contacts 1 (positive) and 3 (earth) on engine speed sender connector.
• ‒ Switch on ignition.
       Specification: min. 4.5 V
• ‒ Switch off ignition.

If no voltage is present:

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

• ‒ → Check wiring for open circuit between test box and 3-pin connector using current flow diagram.
       Contact 1+socket 87
       Contact 2+socket 82
       Contact 3+socket 108
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no wiring fault is detected and voltage was present between contacts 1+3:

• ‒ Replace engine speed sender (G28)
  , item 14 .

If no wiring fault is detected and no voltage was present between contacts 1+3:

• ‒ Replace engine control unit
  .