Volkswagen Workshop Service and Repair Manuals

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

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ 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

• ● Engine cold

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 1 for "Display group number 1" and confirm entry with Q key.

Functional check of sender

• ‒ Observe coolant temperature figure in display zone 2. The temperature figure must
       Increase uniformly and without interruption.

• If a temperature figure is displayed which deviates greatly from the senders ambient temperature, check sender wiring for transfer resistances.

Notes:

• ◆ The fault reader display can increase in 2 °C steps.
• ◆ If a coolant temperature sender fault is indicated in fault memory even though the temperature increases uniformly, the engine control unit is in the emergency running mode and calculates the coolant temperature.

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.

If the figure does not increase uniformly:

• ‒ Renew coolant temperature sender (G62) => Page 24-10 , item 19 .

If a G62 fault is indicated in fault memory even though the figure increases uniformly:

• ‒ Switch off ignition.

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

Note:

Gradual introduction of coolant temperature sender with new connector and changed connector assignment.

• ‒ → Pull 4 pin connector -1- off coolant temperature sender (G62) -2-.

Vehicles with old connector shape

• ‒ Check wiring between test box and 4 pin connector for open circuit using current flow diagram.
       Contact 1+ socket 70
       Contact 3+ socket 53
       Wire resistance: max. 1.5 ω

Vehicles with new connector shape

• ‒ → Check wiring between test box and 4-pin connector for open circuit using current flow diagram.
       Contact 4+socket 70
       Contact 3+socket 53
       Wire resistance: max. 1.5ω

Continuation for both connector shapes

• ‒ Additionally check each of the wires for short to one another, and for short to battery positive or earth.
  Specification:∞ω

If no fault in wire is detected:

Vehicles with old connector shape

• ‒ → Perform resistance measurement on coolant temperature sender (G62) contact 1 and 3.

Vehicles with new connector shape

• ‒ → Perform resistance measurement on coolant temperature sender (G62) contact C and D.

→ Scale A shows resistance values for temperature range 0...50 °C and scale B the values for temperature range 50...100 °C.

Examples:

• ◆ 30 °C corresponds to a resistance from 1500...2000 ω
• ◆ 80 °C corresponds to a resistance from 275...375 ω

If the specification is not obtained:

• ‒ Renew coolant temperature sender (G62) => Page 24-10 , item 19 .