GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

Spark Plug Wires

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The spark plug wiring used with electronic ignition systems is a carbon impregnated cord conductor, incased in 8 mm diameter silicone rubber insulation. The silicone jacket withstands very high temperatures and provides an excellent insulator for the higher voltage of the electronic ignition system. Silicone spark plug boots form a tight seal on the plug.

When it becomes necessary to replace spark plug wires, because of age or breakage, it is recommended that you purchase a wire set for your specific engine model. These wire sets are precut to the proper length, and already have the boots installed.

The material used to construct the spark plug cables is very soft. This cable will withstand more heat and carry higher voltage, but scuffing and cutting becomes easier. The spark plug cables must be routed correctly to prevent chaffing or cutting.

TESTING



Visually inspect the spark plug wires for burns, cuts, or breaks in the insulation. Check the spark plug boots and the nipples on the distributor cap and/or coil(s). Replace any damaged wiring. If no physical damage is obvious, the wires can be checked with an ohmmeter for excessive resistance and continuity.

At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring.

Every 50,000 miles (80,000 Km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

To check resistance, disconnect plug wires (do only one at a time) from the spark plug and distributor cap or coil pack.



Connect one lead of an ohmmeter to the spark plug side of the wire (make sure to contact the metal clip inside the boot).
 
Attach the other lead of the ohmmeter to the distributor (coil pack) side of the wire. Again, make sure you contact the metal clip.
 
Spark plug wire resistance is a function of length, the longer the wire the greater the resistance. You should replace any wire with a resistance over 7k ohms per foot.
 
Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.
 



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Fig. Calibrate (zeroing) the ohm meter before using it



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Fig. Make one connection at the spark plug end and . . .



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Fig. . . . one connection at the coil end to check the plug wire resistance



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Fig. Checking the resistance of the spark plug wire

removal & installation




NOTE
To avoid confusion label, remove, and replace spark plug cables one at a time, where possible.

Use care when removing spark plug wire boots from spark plugs. Grasp the wire by the rubber boot. Twist and pull the boot and wire from the spark plug. Never pull on the plug wire directly, or it may become separated from the connector inside the boot. Twist the boot 1 / 2 turn before trying to pull the boot off. Pull only on the boot, pulling on the wire could cause separation or breakage.

3.0L Engine
  1. Remove the oil filler tube.
  2.  
  3. Remove the A/C compressor hose bracket bolt from the engine, and reposition the A/C compressor hose.
  4.  
  5. Reposition harness channel.
  6.  
  7. Remove the spark plug boots from the spark plugs.
    1. Use the spark plug boot remover tool attached to the spark plug boot.
    2.  

  8.  
  9. Remove the spark plug wire harness from the routing retainers on the valve covers and from the ignition coil.
  10.  

To install:


NOTE
When replacing the spark plug wire harness (secondary wiring), route the wire harnesses correctly through the proper retainers. Failure to route the wire harnesses properly can lead to radio ignition noise, cross-firing of the spark plugs, pinched wires and /or shorting of the leads to ground.

  1. Connect the spark plug wires to the ignition coil.
  2.  
  3. Install the spark plug wires to the routing retainers on the valve covers.
  4.  
  5. Connect the spark plug boots to the spark plugs.
  6.  
  7. Position the wiring harness channel and attach it in the proper position using the channel bolts. Tighten to 71 inch lbs. (8 Nm).
  8.  
  9. Reposition the A/C compressor hose, and attach the compressor hose bracket to the engine. Tighten to 71 inch lbs. (8 Nm).
  10.  

4.5L and 4.9L Engines


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Fig. Disconnecting the spark plug cable at the distributor assembly

  1. Disconnect the spark plug cables at the distributor assembly.
  2.  
  3. Disconnect the spark plug wires at the spark plugs.
  4.  


NOTE
Use care when removing the spark plug boots from the spark plugs. Twist the boot 1 / 2 turn before removing and then pull on the boot only. Do not pull on the wire, as it may damage the spark plug cable.

  1. Remove the spark plug channel from the engine.
  2.  
  3. Remove the spark plug wire from the engine.
  4.  

To install:

  1. Position the spark plug wire assembly on top of the engine. Install the plug wire channel.
  2.  
  3. Install the spark plug wire at the spark plug. Make sure the wires are fully seated on the plugs.
  4.  
  5. Install the spark plug wires at the distributor assembly. Secure wires in position.
  6.  

4.6L Engine
  1. Disconnect the spark plug cables at the Ignition Control Module (ICM) assembly.
  2.  
  3. Disconnect the spark plug wires at the spark plugs.
  4.  


NOTE
Use care when removing the spark plug boots from the spark plugs. Twist the boot 1 / 2 turn before removing and then pull on the boot only. Do not pull on the wire, as it may damage the spark plug cable.

  1. Remove the spark plug channel from the camshaft cover and the intake manifold.
  2.  
  3. Remove the spark plug wire from the engine.
  4.  

To install:

  1. Position the spark plug wire assembly on top of the engine. Install the plug wire channel onto the front camshaft cover and intake manifold.
  2.  
  3. Install the spark plug wire at the spark plug. Make sure the wires are fully seated on the plugs.
  4.  
  5. Install the spark plug wires at the ICM assembly.
  6.  



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Fig. Ignition Control Module (ICM) assembly and spark plug cables-4.6L engine

 
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