1987 Audi 5000 CS, AutomaticFACTORY OEM SERVICE PROCEDURE

All Models

  1. Item Being Tested - Return Pump Relay (Off Position) With ignition on, place ABS tester in program switch position No. 3. Lamps No. 1 and 3 (Green) must come on. If lamps come on, TEST 3 is completed.
  2. If lamp No. 4 (Red) comes on, replace defective return pump relay. After replacing relay, check that ground lead for hydraulic modulator is tight. If okay, turn ignition off and remove plug connector on hydraulic modulator.
  3. Use ohmmeter to check continuity between terminal No. 9 in socket on hydraulic modulator and terminal No. 30 in relay socket for return pump. If there is no continuity, replace hydraulic modulator. If continuity exists, go to next step.
  4. Use ohmmeter to check continuity between terminal No. 9 in socket on hydraulic modulator and positive terminal on return pump. See Figure - Figure . If there is no continuity, replace hydraulic modulator. If continuity exists, go to next step.
  5. Use ohmmeter to check continuity between terminal No. 9 in plug for hydraulic modulator and terminal No. 14 in plug for ABS control unit. If there is no continuity, repair wiring harness to restore continuity.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.