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
• ◆ Chilling spray (commercially available)

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 ignition must be switched on.
  (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, 0 and 3 for "Display group number 3" and confirm entry with Q key.

• ‒ Check the specification for intake manifold temperature sender(display zone 4):

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

Evaluating display group 3

Checking wiring:

• ‒ Switch off ignition.

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.

• ‒ → Pull 2 pin connector -1- off intake manifold temperature sender (G72) -2-.
• ‒ Check wiring between test box and 2 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 36
       Contact 2+socket 33
       Wire resistance: Max. 1.5 ω
• ‒ Check wire between control unit connector and 2 pin connector contact 2 for short to wire contact 1 and to vehicle earth, according to current flow diagram.
       Contact 2+socket 36
       Contact 2+vehicle earth
       Specification: ∞ω
• ‒ Additionally check both wires for short to battery positive.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ Perform resistance measurement on intake manifold temperature sender (G72) contacts 1+2, resistance figures => Page 24-19 , Fig. 1

If the specification is not obtained:

• ‒ Replace intake manifold temperature sender (G72)

Continuation of check when display = ambient temperature:

• ‒ → Remove intake manifold temperature sender (G72) (plug remains connected).
• ‒ Read-off intake manifold temperature figure in display zone 4.
• ‒ Spray sender with a commercially available chilling spray and at the same time observe the temperature figure. The temperature figure must
       decrease.

If the specification is not obtained:

• ‒ Replace intake manifold temperature sender (G72)
• ‒ Read-out the readiness code=> Page 01-35 .