Hummer H2. Manual - part 1471

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Twist each spark plug 1/2 turn.  

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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. 

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Twist each spark plug boot 1/2 turn.  

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

Spark Plug Wire Length V8 

Fig. 161: Spark Plug Wires 
Courtesy of GENERAL MOTORS CORP. 

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The Melco(R), square design, uses a spark plug wire (1) that is 145 mm (5.70 in) length cable seal to 
cable seal.  

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The Delphi(R), round design uses a spark plug wire (2) that is 110 mm (4.30 in) length cable seal to cable 
seal. 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

Fig. 162: Melco(R) Square Design & Delphi(R) Round Design 
Courtesy of GENERAL MOTORS CORP. 

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

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

Fig. 163: Melco(R) & Delphi(R) Coil Mounting Brackets  
Courtesy of GENERAL MOTORS CORP. 

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Melco(R), square design, coil mounting bracket (1).  

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Delphi(R), round design, coil mounting bracket (2).  

Installation Procedure 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

Fig. 164: Spark Plug Wire & Boot 
Courtesy of GENERAL MOTORS CORP. 

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: 

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

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Reinstall any loose boot.  

SPARK PLUG INSPECTION 

Spark Plug Usage 

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Verify that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. 
Refer to Ignition System Specifications for the correct spark plug. 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2