GM Full-Size Trucks 1980-1987 Repair Guide

Component Replacement

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INTEGRAL IGNITION COIL



See Figures 1, 2, 3, 4, 5, 6, 7, 8 and 9

The integral ignition coil may be removed with the distributor cap installed in the vehicle or with the cap removed for easy access. If the coil is removed with the cap still installed on the distributor, some of the below steps may be skipped as noted.

Disconnect the negative battery cable. Remove the ignition wire set retainer from the top of the distributor cap. If the cap is being removed from the vehicle, keep the spark plug wires attached to the retainer for ease of installation.

If distributor is not equipped with a spark plug wire set retainer, it will be less hassle to remove the coil while the cap is still installed in the vehicle. If the cap must be removed, the spark plug wires should be tagged to assure proper installation.



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Fig. Fig. 1: "Coil in Cap" Distributor



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Fig. Fig. 2: Ignition coil attaching screws



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Fig. Fig. 3: Remove the coil cover retaining screws



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Fig. Fig. 4: There should be at least 2 screws on most coil covers. The rear screw may be more difficult to access

  1. If the cap is being removed from the vehicle, disconnect the feed and module terminal wire connectors from the distributor cap.
  2.  
  3. If the cap is being removed, release the four latches by depressing and turning using a screwdriver, then remove cap and coil assembly from the distributor housing.
  4.  



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Fig. Fig. 5: Once the screws are removed, lift the cover from the distributor cap for access to the ignition coil

  1. Remove ignition coil cover attaching screws and lift the cover off the distributor cap.
  2.  
  3. Remove ignition coil attaching screws. Using a pair of needle nose pliers, carefully lift the coil with leads from the end of the cap.
  4.  



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Fig. Fig. 6: Loosen and remove the screws attaching the ignition coil to the distributor cap



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Fig. Fig. 7: Make sure all 4 screws are removed before trying the separate the coil from the cap

  1. Remove the ignition coil assembly from the cap, then remove the arc seal.
  2.  



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Fig. Fig. 8: Needle nose pliers may be used to withdraw the coil leads from the cap



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Fig. Fig. 9: Be careful to just remove the coil leads and not to excessively stretch or bend the wires

  1. Clean with soft cloth and inspect cap for defects. Replace cap, if needed.
  2.  
  3. To install the new coil and cover into the cap, reverse the Steps for removal.
  4.  

Pick-up coil



  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring connector from the cap.
  4.  
  5. Turn four latches using a screwdriver and remove cap and coil assembly from the distributor housing.
  6.  
  7. On all distributors, including distributors with Hall Effect Switch, remove rotor and disconnect the pickup coil leads from ignition module.
  8.  
  9. Mark distributor shaft and gear so they can be reassembled in same position.
  10.  
  11. Drive out roll pin.
  12.  
  13. Remove gear and pull shaft assembly from distributor.
  14.  
  15. Remove three attaching screws and remove magnetic shield.
  16.  
  17. Remove retaining ring, pickup coil, magnet and pole piece.
  18.  
  19. Installation is the reverse of the removal procedure.
  20.  

DISTRIBUTOR CAP



See Figures 10, 11, 12, 13, 14, 15 and 16

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the retainer and spark plug wires from the cap. Be sure to note the cap position and spark plug wire location. If the vehicle is not equipped with a wire retainer, the spark plug wires should be labeled to assure proper installation.
  4.  



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Fig. Fig. 10: If the wire retainer is missing, be sure to tag the spark plug wires before they are disconnected from the cap



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Fig. Fig. 11: Using a screwdriver, carefully release the locktab on the outer distributor electrical connector



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Fig. Fig. 12: Once the locktab is released, grasp and withdraw the connector by hand

  1. Use a screwdriver to carefully release the locktabs and disconnect the wiring harness connectors from the distributor cap.
  2.  
  3. Depress and release the 4 distributor cap-to-housing retainers and lift off the cap assembly.
  4.  
  5. Remove the 4 coil cover screws and cover.
  6.  
  7. Using a finger or a blunt tip, push the spade terminals up out of the distributor cap.
  8.  



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Fig. Fig. 13: The inner connector is released in the same manner as the outer connector, but be careful the locktabs are easy to break off



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Fig. Fig. 14: With the locktab released, the inner connector may be removed by hand

  1. Remove all 4 coil screws and lift the coil, coil spring and rubber seal washer out of the cap coil cavity.
  2.  
  3. Using a new distributor cap, reverse the above procedures to assemble, being sure to clean and lubricate the rubber seal with dielectric lubricant.
  4.  



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Fig. Fig. 15: Use a screwdriver to release the distributor cap latches by depressing and turning counterclockwise



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Fig. Fig. 16: With all wiring disconnected and the latches released, the distributor cap may be lifted from the distributor assembly

ROTOR



See Figures 17 and 18

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring harness connectors and module wire connectors from the distributor.
  4.  

On some vehicles the spark plug wires may contain too little play to reposition the cap with them attached. If so, it may be necessary to remove the distributor cap completely for access to the rotor. As always, if there is no retainer, be sure to tag all wires before disconnecting them from the cap.



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Fig. Fig. 17: Using a screwdriver, loosen and remove the rotor retaining screws

  1. Depress and release the 4 distributor cap to housing retainers and lift off the cap assembly with the spark plug wires attached. Reposition the cap and wires for access to the rotor.
  2.  



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Fig. Fig. 18: The rotor should be checked for wear or corrosion. If the rotor is in question, it is best to replace it.

  1. Remove the two rotor attaching screws and rotor.
  2.  

A magnetic tipped screwdriver will greatly reduce the risk of dropping and loosing the screws behind the distributor housing and engine.

  1. Reverse the above procedure to install.
  2.  

VACUUM ADVANCE



See Figures 19, 20 and 21

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the distributor cap and rotor as previously described.
  4.  



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Fig. Fig. 19: Disconnect the hose from the vacuum advance unit



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Fig. Fig. 20: Remove the advance unit retaining screws. The ignition module was removed for clarity only.



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Fig. Fig. 21: Separate the advance unit linkage from the distributor and remove it from the vehicle

  1. Disconnect the vacuum hose from the vacuum advance unit.
  2.  
  3. Remove the two vacuum advance retaining screws, pull the advance unit outward, rotate and disengage the operating rod from its tang.
  4.  
  5. Reverse the above procedure to install.
  6.  

IGNITION MODULE



See Figures 22, 23, 24, 25, 26, 27 and 28

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the distributor cap and rotor as previously outlined in this Section.
  4.  



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Fig. Fig. 22: Remove the ignition module retaining screws



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Fig. Fig. 23: Remove the capacitor retaining screw

  1. Remove two module attaching screws and the capacitor attaching screw. Lift module, capacitor and harness assembly from base.
  2.  
  3. Disconnect wiring harness from module. If access is difficult, the module assembly may by pivoted upwards as the harness allows.
  4.  



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Fig. Fig. 24: Lift the capacitor and module assembly from the distributor housing



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Fig. Fig. 25: Disengage the module harness connector



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Fig. Fig. 26: If the module is to be replaced, separate the module from the capacitor assembly



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Fig. Fig. 27: Be sure to coat the mating surfaces with silicone lubricant when replacing the HEI module



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Fig. Fig. 28: Module removed

To install:
  1. Install module, wiring harness, and capacitor assembly. Use silicone dielectric lubricant on housing under module.
  2.  


WARNING
Failure to use the silicone dielectric lubricant on the ignition module will drastically shorten the ignition module's life.

  1. Install the rotor to the distributor assembly.
  2.  
  3. Install the distributor cap and wires.
  4.  
  5. Connect the negative battery cable.
  6.  

 
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