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
       ▸ 07.93: Cable V.A.G 1551/1
       08.93 ▸: 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 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 .)

• ‒ Input 08 for "Read measured value block" function and confirm with Q key.

• ‒ Input 01 for "Display group number" and confirm with Q key.

• ‒ Observe coolant temperature figure.
       Digifant 3.0 = Display zone 1
       Digifant 3.2 = Display zone 2

     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 -40 °C:

• ‒ → Pull 2 pin connector -1- of coolant temperature sender (G62) -2-.
• ‒ Bridge connector contacts with aux. cables from V.A.G 1594 and observe display.

Display 120 ° C:

• ‒ Replace coolant temperature sender -2-.

Display -40 ° C:

• ‒ Press ⇒key.
• ‒ Input 06 for "End output" and confirm with Q key.
• ‒ Switch off ignition.

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wire between test box socket 14+2 pin connector contact 1 for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wire for short to battery positive.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ Renew Digifant control unit (J169)
  , item 11 .

Continuation of check when display = 120 °C:

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

Display -40 ° C:

• ‒ Replace coolant temperature sender -2-.

Display 120 ° C:

• ‒ Press ⇒key.
• ‒ Input 06 for "End output" and confirm with Q key.
• ‒ Switch off ignition.
• ‒ Pull connector off Digifant control unit.
• ‒ Check wire between control unit connector and 2 pin connector contact 1 for short to wire contact 2 and to vehicle earth, according to current flow diagram.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ Renew Digifant control unit (J169)
  , item 11 .

Continuation of check when display = coolant temperature:

Functional check of sender

• ‒ Observe coolant temperature figure.
       Digifant 3.0 = Display zone 1
       Digifant 3.2 = Display zone 2
  The temperature figure must
       rise uniformly without interruption.

Notes:

• ◆ If the display on fault reader jumps by 2...5 °C, it is a control unit fault and not caused by a defective sender.
• ◆ 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.
• ‒ Input 06 for "End output" and confirm with Q key.