GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Cooling 🢒 Glow Plug Relay Replacement

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable(s).
  2. Remove the air cleaner layer. Refer to Air Cleaner Replacement .

    3. Object Number: 740815 Size: SH
  3. Remove the battery supply wiring harness nut (1) and harness connector (2).
  4. Remove the glow plug wiring harness nuts and harness connectors (4,6).
  5. Release the wiring harness connectors (3,5) at the glow plug relay (8).
  6. Remove the two glow plug relay mounting nuts.
  7. Remove the glow plug relay from the mounting studs.

Installation Procedure
  1. Install the glow plug relay on the mounting studs.

    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 glow plug relay mounting nuts.

    3. Tighten
    Tighten the nuts to 42 N·m (31 lb ft).


    Object Number: 740815 Size: SH
  3. Install the wiring harness connector (3,5) to the relay (8).
  4. Install the glow plug wiring harness and nuts and harness connectors (4,6).

    5. Tighten
    Tighten the nuts to 5 N·m (44 lb in).

  5. Connect the wiring harness connectors (3,5) at the glow plug relay (8).
  6. Install the battery supply wiring harness nut (1) and harness connector (2) on the glow plug relay (8).

    7. Tighten
    Tighten the nut to 5 N·m (44 lb in).

  7. Install the upper intake manifold sight shield.

    8. Tighten
    Tighten the bolt to 9 N·m (80 lb in).

  8. Install the air cleaner layer. Refer to Air Cleaner Replacement .
  9. Connect the negative battery cables.