GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Component Replacement

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See Figures 1, 2 and 3



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Fig. Fig. 1: Exploded view of a common non-EST distributor assembly



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Fig. Fig. 2: Exploded view of a common EST distributor assembly - without sealed module connectors



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Fig. Fig. 3: Exploded view of a common EST distributor assembly - with sealed module connectors

REMOVAL & INSTALLATION



Ignition Coil

See Figures 4, 5 and 6

  1. Disconnect the negative battery cable.
  2.  
  3. Disengage the primary electrical wiring connector and the coil-to-distributor high tension cable from the ignition coil.
  4.  
  5. Remove the coil attaching bolts, then remove the coil from the engine.
  6.  

To install:
  1. Position the coil to the engine and secure using the retainers.
  2.  
  3. Engage the primary electrical wiring connector and the coil-to-distributor high tension cable to the ignition coil.
  4.  
  5. Connect the negative battery cable.
  6.  



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Fig. Fig. 4: Disconnect the coil-to-distributor high tension cable from the top of the ignition coil



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Fig. Fig. 5: Disengage any electrical wiring connectors from the coil



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Fig. Fig. 6: Loosen and remove the retaining bolts, then remove the coil from the bracket

Distributor Cap

See Figures 7, 8, 9 and 10

  1. Disconnect the negative battery cable and if necessary for access, remove the air cleaner assembly.
  2.  
  3. Remove the retainer and spark plug wires from the cap. If there is no wire retainer, be sure to tag all wires before disconnecting them from the distributor cap. Tagging wires will help preserve the proper firing order and greatly ease cap installation.
  4.  
  5. If retained by spring loaded locktabs, depress, twist and release the distributor cap-to-housing locktabs, then lift off the cap assembly. Most integral coil distributor caps will be retained by 2 spring loaded locktabs, though some models may use more.
  6.  
  7. If retained by mounting screws, loosen the screws, then remove the cap from the distributor assembly.
  8.  

To install:
  1. Install the cap to the distributor assembly and secure using the housing retainers.
  2.  
  3. Install the spark plug wires and retainer to the cap. If no wire retainer is used, carefully connect the wires to the cap as tagged during removal.
  4.  
  5. Connect the negative battery cable.
  6.  



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Fig. Fig. 7: Disconnect the coil wire from the center of the distributor cap



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Fig. Fig. 8: If there is no wire retainer, tag and disconnect the spark plug wires from the top of the cap



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Fig. Fig. 9: Release the spring-loaded locktabs, then remove the cap from the distributor



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Fig. Fig. 10: Lift the cap from the distributor assembly

Rotor

See Figures 11 and 12

  1. Disconnect the negative battery cable and if necessary for access, remove the air cleaner assembly.
  2.  
  3. Remove the distributor cap from the housing assembly.
  4.  

Although most rotors can only be installed in one direction, it is still wise to note the position of the rotor before removal to assure proper installation and ignition timing.

  1. Remove the rotor attaching screw(s), if equipped, and note the position of the rotor, then remove the rotor from the distributor.
  2.  

To install:
  1. Install the rotor facing in the direction noted earlier, then if applicable, secure the rotor using the attaching screw(s).
  2.  
  3. Install the distributor cap to the housing assembly.
  4.  
  5. Connect the negative battery cable.
  6.  



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Fig. Fig. 11: Loosen and remove the rotor retaining screws



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Fig. Fig. 12: Lift the rotor from the distributor assembly

Ignition Module

See Figures 13, 14, 15, 16, 17, 18, 19 and 20

NON-EST DISTRIBUTOR

Some non-EST distributors may require a partial disassembly of the distributor in order to remove and replace the ignition module. Though most modules are replaceable without disassembling the distributor, removing the distributor assembly from the engine will make access to the components easier. If you wish to avoid removing the distributor from the engine, remove the cap and rotor to see if access to the module retainers and connectors is possible with the distributor installed, then make your decision on how to proceed.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the distributor cap and position it aside with the wiring still attached. If necessary, tag and disconnect all or some of the wiring in order to position the cap out of the way.
  4.  
  5. If necessary to access the module or if distributor disassembly is necessary, remove the distributor from the engine and place it on a work bench. Be sure to matchmark the rotor and housing before and after removal.
  6.  
  7. If necessary, remove the rotor from the distributor assembly. If applicable, remove the packing ring and the cover.
  8.  
  9. If applicable, remove the electrical harness-to-distributor screw.
  10.  
  11. Disengage the electrical harness connectors from the ignition module.
  12.  
  13. If the distributor is being disassembled, use two medium prybars to carefully pry the pole piece from the distributor shaft, then remove the roll pin.
  14.  
  15. Remove the ignition module retaining screws, then lift the module from the distributor. If equipped, be sure to remove the spacers from the module.
  16.  
  17. If the module is suspected as being defective, take it to a module testing machine and have it tested.
  18.  

To install:
  1. Apply a coat of silicone lubricant to the base of the ignition module to aid in heat dissipation.
  2.  
  3. Install the ignition module to the distributor assembly and secure using the retainers. If equipped, be sure to properly position the spacers during installation.
  4.  
  5. If removed, install the pole piece onto the distributor shaft, followed by a new roll pin.
  6.  

If the breaker plate was loosened during distributor disassembly, use a 0.12-0.20 in. (9-10mm) feeler gauge to measure the air gap between the pole piece and the breaker plate stator.

  1. Engage the electrical harness connectors to the ignition module, then if equipped, install the harness retaining screw.
  2.  



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Fig. Fig. 13: Disengage one or both of the module wiring connectors. The coil wiring may be left connected to the module until it is removed from the distributor



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Fig. Fig. 14: Loosen and remove the module retainers



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Fig. Fig. 15: Remove the module from the distributor; in this case the coil wiring is still attached



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Fig. Fig. 16: Disengage the remaining wiring from the module



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Fig. Fig. 17: Coat the base of the new module with silicone lubricant to aid in heat dissipation



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Fig. Fig. 18: Position the new module to the distributor assembly and engage the wiring

  1. If applicable, install the packing ring and cover.
  2.  
  3. Install the rotor to the distributor assembly.
  4.  
  5. If removed, align the matchmarks made earlier and install the distributor to the engine. Be sure the rotor is facing the proper direction and matchmarks once the distributor is fully installed.
  6.  
  7. Install the cap to the distributor assembly. If any wiring was disconnected, be sure to engage it as tagged or noted during removal.
  8.  
  9. Connect the negative battery cable.
  10.  



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Fig. Fig. 19: Removing the pole piece while disassembling the distributor



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Fig. Fig. 20: Removing the roll pin - NOTE that on some distributors, the roll pin is mounted much higher on the shaft

EST DISTRIBUTOR

The ignition modules are located inside the distributor; they may be replaced without removing the distributor from the engine.

  1. Disconnect the negative battery terminal.
  2.  
  3. Remove the distributor cap and the rotor.
  4.  

Although most rotors can only be installed in one direction, it is still wise to note the position of the rotor before removal to assure proper installation and ignition timing.

  1. If the flange of the distributor shaft, is positioned above the module, place a socket on the crankshaft pulley bolt and rotate the crankshaft (turning the distributor shaft) to provide clearance to the ignition module. Since this will change the rotor position it may be wise to reinstall the rotor before turning in order to make new alignment marks.
  2.  
  3. Remove the ignition module-to-distributor screws, lift the module and disengage the electrical connectors from it.
  4.  
  5. If the module is suspected as being defective, take it to a module testing machine and have it tested.
  6.  

To install:
  1. Apply a coat of silicone lubricant to the base of the ignition module (along the module-to-distributor mounting surface) to aid in heat dissipation.
  2.  
  3. Engage the module electrical wiring and install the ignition module to the distributor assembly, then secure using the retaining screws.
  4.  
  5. Install the rotor to the distributor assembly as noted during removal.
  6.  
  7. Install the cap to the distributor assembly.
  8.  
  9. Connect the negative battery cable.
  10.  

HEI SYSTEM TACHOMETER HOOKUP



These vehicles are equipped with externally mounted ignition coils. Connect one tachometer lead to the TACH terminal on the ignition coil and connect the other one to a suitable ground.


CAUTION
Never ground the TACH terminal; serious ignition module and coil damage will result. If there is any doubt as to the correct tachometer hookup, check with the tachometer manufacturer.

 
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