GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Classic 🢒 Body 🢒 Wiring 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. Remove the nut retaining the positive battery cable lead to the underhood electrical center, then reposition the cable lead away from the electrical center.
  3. Remove the electrical center cover.

    4. Object Number: 736009 Size: SH
  4. Remove all of the fuses and the relays.

    5. Object Number: 736049 Size: SH
  5. Reach under the front of the electrical center and press up on the relief in order to release the retainer tab.
  6. While pressing up, slide the electrical center forward.

    7. Object Number: 736055 Size: SH
  7. Disconnect the electrical cable retainers at the rear of the electrical center.
  8. Release the box retainer next to the electrical cables.

    9. Object Number: 736061 Size: SH
  9. Turn the electrical center upside down and open the lower cover.

    10. Object Number: 321477 Size: SH
  10. Disconnect the instrument panel (I/P) wiring harness individual connectors from the junction block.
  11. Loosen the bolts retaining the engine, I/P, and forward lamp wiring harness connectors to the junction block.

    12. Object Number: 321473 Size: SH
  12. Disconnect the engine wiring harness connector from the junction block.

    13. Object Number: 321469 Size: SH
  13. Disconnect the I/P wiring harness connector from the junction block.

    14. Object Number: 321458 Size: SH
  14. Disconnect the forward lamp wiring harness connector from the junction block.
  15. Remove the electrical center box.

Installation Procedure
  1. With the electrical center turned upside down, install the electrical center box into the electrical center.

    2. Object Number: 321458 Size: SH
  2. Connect the forward lamp wiring harness connector to the junction block.

    3. Object Number: 321469 Size: SH
  3. Connect the I/P wiring harness connector to the junction block.

    4. Object Number: 321473 Size: SH
  4. Connect the engine wiring harness connector to the junction block.

    5. 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.

  5. Install the bolts retaining the engine, I/P, and forward lamp wiring harness connectors to the junction block.

    6. Tighten
    Tighten the electrical center junction block bolts to 7 N·m (62 lb in).


    Object Number: 321477 Size: SH
  6. Connect the I/P wiring harness individual connectors to the junction block.

    7. Object Number: 736055 Size: SH
  7. Connect the retainers for the electrical cable at the rear of the electrical center.
  8. Install the box retainers by the electrical cables.

    9. Object Number: 736061 Size: SH
  9. Close the lower cover of the electrical center.
  10. Turn the electrical center right side up.
  11. Attach the box retainer next to the electrical cables.
  12. Connect the electrical cable retainers at the rear of the electrical center.

    13. Object Number: 736049 Size: SH
  13. Slide the electrical center to the rear until the center snaps into the retainer tab.

    14. Object Number: 736009 Size: SH
  14. Install all of the fuses and the relays.
  15. Install the electrical center cover.
  16. Install the positive battery cable lead to the stud on underhood electrical center, then install the positive battery cable lead retaining nut.

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

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