Checking operation and power supply of fuel pump

Special tools and workshop equipment required

Removal wedge -3409-

Multimeter e.g. hand-held multimeter -V.A.G 1526E-

Auxiliary measuring set -V.A.G 1594C-

Vehicle diagnostic tester

Test prerequisites

Fuel pump control unit -J538- OK → Vehicle diagnostic tester.

Test sequence:

Function of fuel pump is checked using final control diagnosis.

• Observe safety precautions → Chapter.
• Observe rules for cleanliness → Chapter.

• Connect vehicle diagnostic tester-1- as follows:
• Connect diagnosis cable connector -2- to diagnostic connection in driver footwell.
• Switch ignition on.
• Select final control diagnosis for fuel pump in vehicle self-diagnosis program.

The fuel pump must now run slowly up to maximum speed.

Note

The fuel pump runs very quietly.

• Switch off ignition.

If fuel pump does not run:

Golf SV:

• Remove right rear seat → General body repairs, interior; Rep. gr.72.
• Partially detach cover -1- in floor covering at parting line -arrow-.
• Do not detach cover completely from floor covering in order to ensure it is reinstalled in the correct installation position.
• Detach it just enough that the cover can be folded upwards.
• Fold up cover in -direction of arrow-.

Golf and Golf Estate:

• Remove rear bench seat → General body repairs, interior; Rep. gr.72.

Continuation for all vehicles:

• Unclip cover -1- for flange on right at retaining tabs -arrows-, using removal wedge -3409-.

• Unclip sealing grommet -1- downwards from cover -2-.
• Push cover -2- back along wiring harness -3-.

• Press up tab -2- in -direction of arrow A-; to do so, reach between floor panel and fuel tank with your finger.
• At the same time, carefully pull fuel pump control unit -J538--1- out of mounting -in direction of arrow B- by grasping hold of wiring harness -3-.
• Guide fuel pump control unit -J538- out towards interior between fuel tank and floor panel.
• Ensure that connector on fuel pump control unit -J538- is fitted securely by pulling connector without pressing catch. If connector was not inserted correctly, repeat functional check of fuel pump.
• Release and pull off connector from fuel pump control unit -J538-.
• Check contacts on connector and on fuel pump control unit -J538- for damage.

• Check voltage supply between contacts -3- and -4- using multimeter → Current flow diagrams, Electrical fault finding and Fitting locations.
• Use auxiliary measuring set -V.A.G 1594C- to do this.
• Switch ignition on.

Specification: approx. battery voltage

If the specification is not attained:

• Locate and eliminate open circuit referring to current flow diagram → Current flow diagrams, Electrical fault finding and Fitting locations.

If specification is attained on vehicles with front-wheel drive:

• Check that connector -1- is fitted securely by pulling connector without pressing catch. If connector was not inserted correctly, repeat functional check of fuel pump.
• Release and pull off connector -1-.
• Check contacts on plug and on fuel delivery unit for damage.
• Check wiring harness between fuel pump control unit -J538- and fuel delivery unit → Current flow diagrams, Electrical fault finding and Fitting locations.

If specification is attained on vehicles with four-wheel drive:

• Check that connector -1- is fitted securely by pulling connector without pressing catch. If connector was not inserted correctly, repeat functional check of fuel pump.
• Release and pull off connector -1-.
• Check contacts on plug and on fuel delivery unit for damage.
• Check wiring harness between fuel pump control unit -J538- and fuel delivery unit → Current flow diagrams, Electrical fault finding and Fitting locations.

If no fault is detected:

• Draining fuel tank → Chapter
• Pull fuel line -1- off flange. Separate plug-in connectors → Chapter.

Vehicles with auxiliary heater:

• Remove fuel line -2- leading to metering pump -V54- for auxiliary heater from sealing flange.
• To do this, open clip at bottom.
• Carefully pull out fuel line -2-.

Continuation for all vehicles:

• Open locking ring using wrench -T10202-.
• Check that electrical wires between flange and fuel pump are connected.

• Check electrical wiring between flange and fuel pump for continuity using an ohmmeter.
• Check contacts for damage.

If no open circuit can be found:

• Fuel pump is defective, renew fuel delivery unit → Chapter.