Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ 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 1598/18
• ◆ 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) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

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

• ‒ Press keys 0 and 1 for "Display group number 01" 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:

• ◆ Depending upon the temperature level, the display on fault reader will jump by 2...5 °C
• ◆ If irregular engine running occurs in certain temperature ranges and the temperature figure does not increase without interruption, the temperature signal is temporarily interrupted and the sender must be renewed.

• ‒ 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:

• ‒ Replace coolant temperature sender -2-.

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

• ‒ Switch off ignition.
• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

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

• ‒ → Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 35
       Contact 3+socket 12
       Wire resistance: Max. 1.5 ω
• ‒ Check wire between control unit connector and 4 pin connector contact 3 for short to wire contact 1 and to vehicle earth, according to current flow diagram.
       Socket 12 + 35
       Socket 01 + 35
       Socket 35 + vehicle earth
       Specification: ∞ω
• ‒ Additionally check wires for short to battery positive.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ Perform resistance measurement at coolant temperature sender (G62) contacts 1+3, resistance figures => Page 24-30 , Fig. 1

If the specification is not obtained:

• ‒ Renew coolant temperature sender (G62) => Page 24-12 , item 18 .