GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC C-Series Medium Duty Truck B7 🢒 Transmission/Transaxle 🢒 Automatic Transmission - Allison 🢒 Transmission Modulator Valve Replacement

Removal Procedure

    Object Number: 201539 Size: SH
  1. For diesel engines only, remove the vacuum line from the modulator.

    2. Object Number: 201540 Size: SH
  2. Remove the bolt and the clip securing the modulator to the transmission.
  3. Remove the modulator and the seal from the transmission. Discard the seal.

Installation Procedure

    Object Number: 201540 Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  1. Install the modulator and a new seal to the transmission with the bolt and the clip.

    2. Tighten
    Tighten the modulator clip bolt to 20 N·m (15 lb ft).


    Object Number: 201539 Size: SH
  2. For diesel engines only, install the vacuum line to the modulator.