1987 Audi 5000 CS, AutomaticFACTORY OEM SERVICE PROCEDURE

All Models

  1. Item Being Tested - Hydraulic Modulator Diode & ABS Indicator Light Place ABS tester in program switch position No. 15. Voltage reading on ABS tester should be 2.5-8.5 volts and ABS indicator light must dim slightly.
  2. If indicator light does not come on or if voltage reading is incorrect, check indicator light and corresponding power supply wire. To do so, turn ignition off.
  3. Use ohmmeter to check continuity and contact resistance between terminal No. 10 in plug for hydraulic modulator and terminal No. 29 in plug for ABS control unit. If necessary, repair wiring harness to restore continuity or eliminate contact resistance. After repairs, go to next step.
  4. Use ohmmeter to measure continuity between terminals No. 10 and 12 in socket of hydraulic modulator. Note continuity on ohmmeter, and then reverse leads.
  5. Ohmmeter must indicate continuity in one direction only. Replace hydraulic modulator if results are incorrect. If okay, turn ignition on and remove solenoid valve relay. If indicator light comes on, replace hydraulic modulator.
Chapter Navigation
Return to Chapter: Test 15
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.