Volkswagen Workshop Service and Repair Manuals

The engine speed sender (G28) is a speed and reference mark sender. The engine will not start if there is no speed signal. If the speed signal fails when the engine is running, it will cause the engine to stall immediately.

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

• ◆ Test box V.A.G 1598/22
• ◆ 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

• ‒ Remove air cleaner , Fig. 3 .
• ‒ → 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:

• ‒ Remove wiper arms and cowl panel:

=> Electrical system; Repair group 92; windscreen wiper system; removing and installing windscreen wiper system

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

• ‒ → Check wires between test box and 3-pin connector (connector to control unit) for open circuit using current flow diagram.
       Contact 1+socket 62
       Contact 2+socket 53
       Contact 3+socket 67
       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 18 .

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

• ‒ Replace engine control unit
  => Page 24-135 .