Spark Plug Wire Harness Replacement 4.8, 5.3, 6.0L

1. Disconnect the spark plug wire at each spark plug.

•	Twist each spark plug boot 1/2 turn.

•	Pull only on the boot in order to remove the wire from each spark plug.

2. Disconnect the spark plug wire from the ignition coil.

•	Twist each spark plug boot 1/2 turn.

•	Pull only on the boot in order to remove the wires from the ignition coil.

1. The Melco ® (square design) uses a spark plug wire (1) that is 145 mm (5.70in) length cable seal to cable seal.
2. The Delphi ® (round design) uses a spark plug wire (2) that is 110 mm (4.30in) length cable seal to cable seal.

1. There are 2 different manufacturers for the ignition coils. the Melco ® (1) (square design), and the Delphi ® (2) (round design). These 2 coils use 2 different spark plug wire, and mounting brackets.



2. Melco ® (square design) coil mounting bracket(1).
3. Delphi ® (round design) coil mounting bracket(2).

1. Install the spark plug wires at the ignition coil.
2. Install the spark plug wire to each spark plug.
3. Inspect the wires for proper installation:

•	Push sideways on each boot in order to inspect the seating.

•	Reinstall any loose boot.

Spark Plug Wire Harness Replacement 4.3L

1. Disconnect the spark plug wire at each spark plug.

•	Twist the boots 1/2 turn before removing the boots.

•	Pull only on the boot or use a tool designed for this purpose in order to remove the wire from each spark plug.

2. Disconnect the spark plug wire from the distributor.

•	Twist each spark plug boot 1/2 turn.

•	Pull only on the boot or use a tool designed for this purpose in order to remove the wires from the distributor.

Notice: If the boot to wire movement has occurred, the boot will give a false visual impression of being fully seated. Ensure that the boots have been properly assembled by pushing sideways on the installed boots. Failure to properly seat the terminal onto the spark plug will lead to wire core erosion and result in an engine misfire or crossfire condition, and possible internal damage to the engine.

1. Install the spark plug wires at the distributor.
2. Install the spark plug wire to each spark plug.
3. Inspect the wires for proper installation:

•	Push sideways on each boot in order to inspect the seating.

•	Reinstall any loose boot.

•	Wire routings must be kept intact during service and followed exactly when wires have been disconnected or when replacement of the wires is necessary. Failure to route the wires properly can lead to radio ignition noise and crossfiring of the plugs, or shorting of the leads to the ground.

•	Any time the spark plug wires or boots are installed on the spark plugs, new dielectric grease needs to be applied inside the boot.