Cherokee, Grand Cherokee, 1999-2005

Ignition Coil

Print

Removal & Installation



3.7L & 4.7L Engines

An individual ignition coil is used for each spark plug. The coil fits into machined holes in the cylinder head. A mounting stud/nut secures each coil to the top of the intake manifold. The bottom of the coil is equipped with a rubber boot to seal the spark plug to the coil. Inside each rubber boot is a spring. The spring is used for a mechanical contact between the coil and the top of the spark plug. These rubber boots and springs are a permanent part of the coil and are not serviced separately. An O-ring is used to seal the coil at the opening into the cylinder head.

  1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
  2.  
  3. Disconnect electrical connector from coil by pushing downward on release lock on top of connector and pull connector from coil.
  4.  
  5. Clean area at base of coil with compressed air before removal.
  6.  
  7. Remove coil mounting nut from mounting stud.
  8.  
  9. Carefully pull up coil from cylinder head opening with a slight twisting action.
  10.  
  11. Remove coil from vehicle

    Click image to see an enlarged view

    Fig. The 3.7L engine uses 6 dedicated, and individually fired, coils for each spark plug (2)



    Click image to see an enlarged view

    Fig. The 4.7L engine uses 8 dedicated, and individually fired, coils (1) for each spark plug. Each coil is mounted directly to the top of each spark plug

  12.  

To install:

  1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
  2.  
  3. Clean coil O-ring but do not apply any lubricant.
  4.  
  5. Position ignition coil into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
  6.  
  7. Install mounting stud nut and tighten to 70 inch lbs. (8 Nm).
  8.  
  9. Connect electrical connector to coil by snapping into position.
  10.  
  11. If necessary, install throttle body air tube or box.
  12.  

4.0L Engine
  1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
  2.  
  3. Disconnect electrical connector from coil by pushing downward on release lock on top of connector and pull connector from coil.
  4.  
  5. Clean area at base of coil with compressed air before removal.
  6.  
  7. Remove coil mounting nut from mounting stud.
  8.  
  9. Carefully pull up coil from cylinder head opening with a slight twisting action.
  10.  
  11. Remove coil from vehicle.
  12.  

To install:

  1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
  2.  
  3. Check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  4.  
  5. Position ignition coil into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
  6.  
  7. Install coil mounting stud nut.
  8.  
  9. Connect electrical connector to coil by snapping into position.
  10.  
  11. If necessary, install throttle body air tube.
  12.  

4.7L Engine
  1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
  2.  
  3. Disconnect electrical connector from coil by pushing downward on release lock on top of connector and pull connector from coil.
  4.  
  5. Clean area at base of coil with compressed air before removal.
  6.  
  7. Remove coil mounting nut from mounting stud.
  8.  
  9. Carefully pull up coil from cylinder head opening with a slight twisting action.
  10.  
  11. Remove coil from vehicle.
  12.  

To install:

  1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
  2.  
  3. Check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  4.  
  5. Position ignition coil into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
  6.  
  7. Install coil mounting stud nut.
  8.  
  9. Connect electrical connector to coil by snapping into position.
  10.  
  11. If necessary, install throttle body air tube.

    Click image to see an enlarged view

    Fig. The 4.7L V-8 engine uses eight dedicated, and individually fired coil for each spark plug. Each coil is mounted directly to the top of each spark plug

  12.  

5.7L Engine
  1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
  2.  
  3. Unlock electrical connector by moving slide lock first. Press on release lock while pulling electrical connector from coil.
  4.  
  5. Disconnect secondary high-voltage cable from coil with a twisting action.
  6.  
  7. Clean area at base of coil with compressed air before removal.
  8.  
  9. Remove two mounting bolts (note that mounting bolts are retained to coil).
  10.  
  11. Carefully pull up coil from cylinder head opening with a slight twisting action.
  12.  
  13. Remove coil from vehicle.
  14.  
  15. Before installing spark plug cables to either the spark plugs or coils, or before installing a coil to a spark plug, apply dielectric grease to inside of boots.
  16.  

To install:

  1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
  2.  
  3. Before installing spark plug cables to either the spark plugs or coils, or before installing a coil to a spark plug, apply dielectric grease to inside of boots.
  4.  
  5. Position ignition coil into cylinder head opening and push onto spark plug. Twist coil into position.
  6.  
  7. Install 2 coil mounting bolts.
  8.  
  9. Connect electrical connector to coil by snapping into position.
  10.  
  11. Install cable to coil. To prevent ignition crossfire, spark plug cables MUST be placed in cable tray (routing loom) into their original position.
  12.  
  13. If necessary, install throttle body air tube.

    Click image to see an enlarged view

    Fig. An individual ignition coil (1) is used at each cylinder. The coil mounts to the top of the valve cover with two bolts (2). The bottom of the coil is equipped with a rubber boot (3) to seal the spark plug to the coil

  14.  

Testing



To perform a complete test of the eight ignition coils and their circuitry, refer to the DRB scan tool. To do an individual test of the coil only, refer to the following:

Inspect the ignition coil for cracks and for any arcing. Arcing at the secondary end will carbonize the rubber spark plug boot, which if it is reconnected, may cause the coil to fail. Replace coil if any cracks or arcing is found.

Test the resistance (in ohms) of the primary side of the coil by attaching an ohmmeter across the two pins at the electrical connector end of the coil.

Test the resistance (in ohms) of the secondary side of the coil by attaching an ohmmeter from either of the two primary pins to the spring inside the rubber boot at the spark plug opening.

 
label.common.footer.alt.autozoneLogo