Checking fuel pump control unit J538 - vehicles with FSI engine — AUDI

🧭 Before you start

Fits: Audi A6 C6 (4F, 2004–2011)

• Special tools named: V.A.G 1598/39

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• The connector contacts are numbered accordingly on the back of the connector.
• Connect test boxV.A.G 1598/42 to wiring harness with adapter lead V.A.G 1598/39-1 or V.A.G 1598/39-2. Do not connect engine control unit. Connect earth clip of test box to negative terminal of battery 24.

🔧 Engine codes this applies to

📐 28 workshop diagrams for AUK

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Remove rear seat bench (repair group 72).
2. Unscrew cover for flange (right-side) (arrows).
3. Connect hand-held multimeter V.A.G 1526C for voltage measurement with measuring probes and plug-in adapters from adapter set V.A.G 1594C between contacts (1) and (5), as shown in illustration; the electrical connector remains in place. [Note: The connector contacts are numbered accordingly on the back of the connector.]
4. Start engine.
5. Press accelerator pedal quickly to the floor and release again (short throttle burst).

6. Check voltage supply and activation of fuel pump control unit J538.
7. Remove fuel pump control unit J538.
8. Unplug electrical connector (arrow) on fuel pump control unit J538.
9. Connect multimeter between contacts (3) and (4) of connector to measure voltage.
10. Switch on ignition.
11. Eliminate open circuit in wiring (refer to current flow diagram).
12. Remove protective cap.
13. Connect multimeter for voltage measurement with measuring probes and plug-in adapters from auxiliary measuring set V.A.G 1594C between contacts (4) and (5), as shown in illustration; the electrical connector remains in place. [Note: The connector contacts are numbered accordingly on the back of the connector.]
14. Start engine.
15. Press accelerator pedal quickly to the floor and release again (short throttle burst).
16. Switch off ignition.
17. Connect test box V.A.G 1598/42 to wiring harness with adapter lead V.A.G 1598/39-1 or V.A.G 1598/39-2. Do not connect engine control unit. Connect earth clip of test box to negative terminal of battery (repair group 24).
18. ⚠ Electronic components are susceptible to damage. Select the appropriate measuring range before connecting the test leads and observe test requirements. — Check for open circuit and short to positive or earth in the following wiring:
19. Repair open circuit or short circuit in wiring (refer to current flow diagram).
20. Renew fuel pump control unit J538.

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