Audi 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 must be cold.

Test sequence

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (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 4 for "Display group number 4" and confirm entry with Q key.

• ‒ Read off coolant temperature value in display zone 3.

• ‒ Perform check according to following table:

    1)    If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check sender wiring for transfer resistances.

    2)    Check is only possible when the engine is cold.

Continuation of check when display = coolant temperature:

Functional check of sender

• ‒ 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 => Page 01-7.)

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

• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• ‒ Observe coolant temperature value in display zone 3 with engine running. The temperature value must
      increase evenly without interruption.

Notes:

• ◆ Temperature increases in steps of 1.0 °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.
• ‒ Switch off ignition.

If the specification is not obtained:

• ‒ Replace coolant temperature sender (G62) with coolant temperature gauge sender (G2) , item 28.

Continuation of check when display shows -40 °C:

• ‒ → Pull the 4 pin connector off coolant temperature sender (G62) with coolant temperature gauge sender (G2) -arrow-.

• ‒ → Bridge connector contacts 1+3 using aux. cables from V.A.G 1594 and observe display.

Display jumps to 129 °C:

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

• ‒ Replace coolant temperature sender (G62) with coolant temperature gauge sender (G2) , item 28.

If the display remains at -40 °C:

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

• ‒ → Connect test box V.A.G 1598/22 to control unit wiring harness
  => Page 24-121.

• ‒ → Check wires between test box and 4-pin connector (connector to control unit) for open circuit using current flow diagram.
      Contact 1+socket 54
      Contact 3+socket 74
      Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another, to vehicle earth and to battery positive.
      Specification: ∞ω

If no fault is detected in the wiring:

• ‒ Replace coolant temperature sender (G62) with coolant temperature gauge sender (G2) , item 28.

Continuation of check when display shows 129 °C:

• ‒ → Pull the 4 pin connector off coolant temperature sender (G62) with coolant temperature gauge sender (G2) -arrow-.

If the display jumps to -40 °C:

• ‒ Press ⇒key.

• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
• ‒ Switch off ignition.
• ‒ Replace coolant temperature sender (G62) with coolant temperature gauge sender (G2) , item 28.

If display remains at 129 °C:

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

• ‒ → Connect test box V.A.G 1598/22 to control unit wiring harness
  => Page 24-121.

• ‒ → Check wires between test box and 4-pin connector (connector to control unit) for open circuit using current flow diagram.
      Contact 1+socket 54
      Contact 3+socket 74
      Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another, to vehicle earth and to battery positive.
      Specification: ∞ω

If no fault is detected in the wiring:

• ‒ Replace coolant temperature sender (G62) with coolant temperature gauge sender (G2) , item 28.