GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Underhood Electrical Center or Junction Block Replacement

Removal Procedure
  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.

    2. Object Number: 821475 Size: SH
  2. Remove the positive battery cable lead nut from the junction block. Reposition the cable lead away from the junction block.
  3. Remove the junction block cover.

    4. Object Number: 821474 Size: SH
  4. Disengage the electrical cable retainers at the rear of the junction block.
  5. Turn the junction block upside down and open the lower cover.
  6. Loosen the bolts retaining the engine, IP, and forward lamp wiring harness connectors to the junction block.
  7. Disconnect the engine wiring harness connector from the junction block.
  8. Disconnect the IP wiring harness connector from the junction block.
  9. Remove the junction block.

Installation Procedure

    Object Number: 821474 Size: SH
  1. Connect the IP wiring harness connector to the junction block.
  2. Connect the engine wiring harness connector to the junction block.

    3. 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.

  3. Install the underhood junction block connector bolts.

    4. Tighten
    Tighten the underhood junction block connector bolts to 7 N·m (62 lb in).

  4. Turn the electrical center right side up.
  5. Connect the electrical cable retainers at the rear of the junction block.

    6. Object Number: 821475 Size: SH
  6. Install the junction block cover.
  7. Install the positive battery cable lead to the junction block stud. Install the positive battery cable lead nut.

    8. Tighten
    Tighten the positive battery cable lead nut to 10 N·m (89 lb in).

  8. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.