1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4FACTORY OEM SERVICE PROCEDURE

Abs/TCS Modulator Gears: Installation

  1. Install gears in original position on modulator drive shaft. DO NOT allow gears to turn during installation of gear retaining nuts. Piston in modulator can hit bottom of bore, damaging piston.
  2. Insert a drift through holes in gears (not between gear teeth) to recessed hole in modulator base. See Figure. Install gear retaining nuts. Tighten gear retaining nuts to specification. See TORQUE SPECIFICATIONS.
  3. Place modulator upside-down with gears facing you, rotate each gear counterclockwise on ABS modulator, or clockwise on TCS modulator until movement stops. On ABS modulator, rotating gears counterclockwise will position pistons very close to top of modulator bore, making brake bleeding easier. On TCS modulator, rotating gears clockwise will position pistons very close to bottom of modulator bore, making brake bleeding easier.
  4. On ABS and TCS modulators, position motor pack onto modulator, aligning motor pack gears with modulator gears. Install motor pack attaching screws. Tighten motor pack screws to specification. See TORQUE SPECIFICATIONS.
  5. Install gear cover onto bottom of modulator. Tighten gear cover screws to specification. See TORQUE SPECIFICATIONS. Install modulator/motor pack assembly onto vehicle. Bleed brake system. See BLEEDING BRAKE SYSTEM.
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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.

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