GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 6.6L (LLY) 🢒 Engine Wiring Harness Assembly Replacement

Removal Procedure
  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim.
  3. Remove the air cleaner. Refer to Air Cleaner Replacement .

    4. Important: After removing the air cleaner outlet duct, cover the turbocharger opening with tape in order to prevent entry of objects.

  4. Remove the charged air cooler pipes. Refer to Charged Air Cooler Hoses/Pipes Replacement in Engine Mechanical - 6.6L (LLY).

    5. Object Number: 1334881 Size: SH
  5. Disconnect the fuel injection control module (FICM) electrical connectors.

    6. Object Number: 1335443 Size: SH
  6. Remove the left glow plug harness bracket bolts.
  7. Remove the left side glow plug electrical connector nuts from each glow plug.

    8. Object Number: 1335450 Size: SH
  8. Remove the right glow plug harness bracket bolts.
  9. Remove the right side glow plug electrical connector nuts from each glow plug.

    10. Object Number: 1335454 Size: SH
  10. Disconnect the positive crankcase ventilation (PCV) hose clamps and hoses.

    11. Object Number: 1335456 Size: SH
  11. Remove the right PCV pipe bolt .

    12. Object Number: 1335460 Size: SH
  12. Remove the left PCV pipe bolt.

    13. Object Number: 1335462 Size: SH
  13. Remove the PCV pipes.

    14. Object Number: 1335413 Size: SH
  14. Disconnect the engine coolant temperature (ECT) sensor electrical connector.

    15. Object Number: 1335463 Size: SH
  15. Disconnect the exhaust gas recirculation (EGR) valve electrical connector.

    16. Object Number: 1334862 Size: SH
  16. Disconnect the camshaft position (CMP) sensor electrical connector.

    17. Object Number: 1335467 Size: SH
  17. Remove the 2 ground bolts.

    18. Object Number: 1335470 Size: SH
  18. Disconnect the crankshaft position (CKP) sensor electrical connector.

    19. Object Number: 1335476 Size: SH
  19. Remove the tie strap from the electrical harness.

    20. Object Number: 1395838 Size: SH
  20. Disconnect the main engine electrical harness connectors. Lift up on the latches in order to disconnect the connectors.
  21. Remove the main engine electrical harness clip bolt from the bracket.

    22. Object Number: 1334921 Size: SH
  22. Disconnect the barometric sensor electrical connector.

    23. Object Number: 1334916 Size: SH
  23. Remove the main engine electrical harness connector screws.

    24. Object Number: 1335482 Size: SH
  24. Disconnect the fuel pressure control valve electrical connector.

    25. Object Number: 1335490 Size: SH
  25. Disconnect the turbocharger (TC) boost sensor electrical connector.

    26. Object Number: 1335526 Size: SH
  26. Disconnect the oil level sensor electrical harness connector.

    27. Object Number: 1335528 Size: SH
  27. Disconnect the fuel temperature sensor electrical connector.

    28. Object Number: 1335531 Size: SH
  28. Disconnect the glow plug controller electrical connector.

    29. Object Number: 1334926 Size: SH
  29. Disconnect and remove the TC vane position sensor.

    30. Object Number: 1335536 Size: SH
  30. Disconnect the fuel injector electrical connectors.

    31. Object Number: 1335540 Size: SH
  31. Disconnect the TC vane control solenoid valve.

    32. Object Number: 1335543 Size: SH
  32. Disconnect the fuel rail pressure (FRP) sensor electrical connector.

    33. Object Number: 1335546 Size: SH
  33. Disconnect the oil pressure sensor electrical connector.

    34. Object Number: 1335549 Size: SH
  34. Remove the oil level sensor harness bolt.

    35. Object Number: 1336490 Size: SH
  35. Remove the glow plug controller bolts.
  36. Remove the glow plug controller.
  37. Remove the glow plug electrical connector nuts.

    38. Object Number: 1335560 Size: SH
  38. Remove the engine wiring harness.

Installation Procedure

    Object Number: 1335560 Size: SH
  1. Install the engine wiring harness.

    2. Object Number: 1336490 Size: SH
  2. Install the glow plug controller.

    3. Notice: Refer to Fastener Notice in the Preface section.

  3. Install the glow plug controller bolts.

    4. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 1335549 Size: SH
  4. Install the oil level sensor harness bolt.

    5. Tighten
    Tighten the bolt to 40 N·m (30 lb ft).


    Object Number: 1335546 Size: SH
  5. Connect the oil pressure sensor electrical connector.

    6. Object Number: 1335543 Size: SH
  6. Connect the FRP sensor electrical connector.

    7. Object Number: 1335540 Size: SH
  7. Connect the TC vane control solenoid valve.

    8. Object Number: 1335536 Size: SH
  8. Connect the fuel injector electrical connectors.

    9. Object Number: 1334926 Size: SH
  9. Install and connect the TC vane position sensor.

    10. Object Number: 1335531 Size: SH
  10. Connect the glow plug controller electrical connector.

    11. Object Number: 1335528 Size: SH
  11. Connect the fuel temperature sensor electrical connector.

    12. Object Number: 1335526 Size: SH
  12. Connect the oil level sensor electrical harness connector.

    13. Object Number: 1335490 Size: SH
  13. Connect the TC boost sensor electrical connector.

    14. Object Number: 1335482 Size: SH
  14. Connect the fuel pressure control valve electrical connector.

    15. Object Number: 1334916 Size: SH
  15. Install the main engine electrical harness connector screws.

    16. Tighten
    Tighten the screws to 10 N·m (89 lb in).


    Object Number: 1334921 Size: SH
  16. Connect the barometric sensor electrical connector.

    17. Object Number: 1395838 Size: SH
  17. Install the main engine electrical harness with clip to the bracket with bolt.
  18. Connect the main engine electrical harness connectors.

    19. Object Number: 1335476 Size: SH
  19. Install a NEW tie strap to the electrical harness.

    20. Object Number: 1335470 Size: SH
  20. Connect the CKP sensor electrical connector.

    21. Object Number: 1335467 Size: SH
  21. Install the 2 ground bolts.

    22. Tighten
    Tighten the bolts to 34 N·m (25 lb ft).


    Object Number: 1334862 Size: SH
  22. Connect the CMP sensor electrical connector.

    23. Object Number: 1335463 Size: SH
  23. Connect the EGR valve electrical connector.

    24. Object Number: 1335413 Size: SH
  24. Connect the ECT sensor electrical connector.

    25. Object Number: 1335462 Size: SH
  25. Install the PCV pipes.

    26. Object Number: 1335460 Size: SH
  26. Install the left PCV pipe bolt.

    27. Tighten
    Tighten the bolt to 18 N·m (13 lb ft).


    Object Number: 1335456 Size: SH
  27. Install the right PCV pipe bolt .

    28. Tighten
    Tighten the bolt to 18 N·m (13 lb ft).


    Object Number: 1335454 Size: SH
  28. Connect the PCV hoses and clamps.

    29. Object Number: 1335450 Size: SH
  29. Install the right glow plug harness bracket bolts.

    30. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  30. Install the right side glow plug electrical harness to each right side glow plug with nut.

    31. Tighten
    Tighten the glow plug electrical connector nut to 2 N·m (18 lb in).


    Object Number: 1335443 Size: SH
  31. Install the left glow plug harness bracket bolts.

    32. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  32. Install the left side glow plug electrical harness to each left side glow plug with nut.

    33. Tighten
    Tighten the glow plug electrical connector nut to 2 N·m (18 lb in).


    Object Number: 1334881 Size: SH
  33. Connect the FICM electrical connectors.
  34. Remove the tape from the TC openings.

    35. Important: Lubricate the end of the duct prior to installation.

  35. Install the air charged air cooler pipes. Refer to Charged Air Cooler Hoses/Pipes Replacement in Engine Mechanical - 6.6L (LLY).
  36. Install the air cleaner. Refer to Air Cleaner Replacement .
  37. Install the engine cover. Refer to Engine Cover Replacement in Interior Trim.
  38. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.