Volkswagen Workshop Service and Repair Manuals > Golf Mk4 > Power unit | Direct injection and preglow system with distributor-type pump to 04.99 | Fuel preparation system Diesel injection | Checking components and functions

Checking intake manifold flap motorV157

Checking intake manifold flap motor -V157-

Engine codes AGP, AQM

Special tools and workshop equipment required

t	Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with diagnosis cable -V.A.G 1551/3-

t	Adapter -V.A.G 1598/22-

t	Hand multimeter -V.A.G 1526C- or multimeter -V.A.G 1715-

t	Adapter set -V.A.G 1594C-

t	Current flow diagram

Test procedure

–	Connect fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- and select control unit for engine electronics with “address word 01”. Engine must be idling. (Connect fault reader and select engine electronics control unit → Chapter.)

Indicated on display:

–	Press keys 0 and 3 for function “Final control diagnosis”.

Rapid data transfer                 HELP

Select function XX

Indicated on display:

–	Confirm entry with Q key.

Rapid data transfer                    Q

03-Final control diagnosis

Indicated on display:

Activation of the intake manifold flap motor -V157- changes the combustion noise (control motor opens and closes intake manifold flap).

If no changes in the combustion noise can be heard:

–	Press the C button.

–	Press keys 0 and 6 for function “End data transfer” and confirm entry with Q key.

–	Switch off ignition.

Final control diagnosis               ->

Intake manifold flap motor V157

–	Pull connector -1- off intake manifold flap motor -V157--2-.

–	Switch on ignition.

–	Measure supply voltage of intake manifold flap motor -V157- at contact 4 and engine earth, then at contact 4 and 1 of connector.

Specification: approx. battery voltage

If the specification is not reached:

–	Switch off ignition.

–	Connect adapter -V.A.G 1598/22- to control unit wiring harness.

–	Check wiring between adapter and connector for open circuit using current flow diagram. Contact 2+socket 3 contact 3+socket 49.

Cable resistance: max. 1.5 Ω.

–	Also check wiring for short to one another, short to vehicle earth and short to battery positive.

Specification: ∞ Ω.

If no fault in lines is detected:

–	Renew diesel direct injection system control unit -J248- → Chapter.

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