GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Pickup - 4WD (CNG) 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 Engine Control Unit Adapter Replacement

Removal Procedure

    Object Number: 478943 Size: SH
  1. Press the mounting adapter clip (5) away from the AF ECU (6).
  2. Lift the AF ECU from the mounting adapter.
  3. Support the AF ECU and engine harness away from the mounting adapter.

    4. Object Number: 478944 Size: SH
  4. Remove the 4 mounting adapter bolts (1).

Installation Procedure

    Object Number: 478944 Size: SH
  1. Place the mounting adapter on the mounting bracket ensuring the open area of the mounting adapter is facing in-board.

    2. 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.

  2. Install the four mounting bolts (1).

    3. Tighten
    Tighten the bolts to 12 N·m (108 lb in).


    Object Number: 478943 Size: SH
  3. Install the rearward side of the AF ECU (6) into the mounting adapter rear clips.
  4. Press down on the AF ECU until the mounting adapter clip (5) snaps over the AF ECU.