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Home >> Volvo >> 1987 >> 780 AW71L >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System >> Testing >> Circuit Tests >> Hydraulic Modulator Power Circuits
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Hydraulic Modulator Power Circuits

  1. Turn ignition switch to the "OFF" position. Disconnect hydraulic modulator connector. Turn ignition switch to the "ON" position.
  2. Connect negative lead of voltmeter to a good ground. Check voltage at terminals No. 6, 7, 10 and 12. Voltmeter should indicate battery voltage. If there is no voltage present at:
    • 6 - Check fuse No. 2 in main fuse/relay panel.
    • 7 - Attach connector to hydraulic modulator. ABS warning light should illuminate on dashboard. If light does not illuminate, replace bulb.
    • 10 - Check transient surge protector fuse. If fuse is okay, replace transient surge protector.
    • 12 - Check 80-amp fuse on top of right front wheelwell.
  3. Turn ignition switch to the "OFF" position. Check wiring harness to and from hydraulic modulator connector for damage. Attach connector to modulator.
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