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Home >> Cadillac >> 1984 >> Cimarron Standard >> Repair and Diagnosis >> Engine Performance >> Ignition System - HEI-Est >> Testing >> By-Pass Or Faulty Est Check

By-Pass Or Faulty Est Check

  1. With engine at fast idle, check timing. Ground test terminal and note if timing changes. See Figure. If timing does change, system is operating properly. If timing does not change, stop engine and unplug 4-wire EST connector from distributor.
  2. Connect a jumper wire from terminal "A" to "B" on distributor side of EST connector. See Figure. Start engine, ground test terminal and connect test light from battery positive terminal to terminal "C" of EST connector.
  3. If engine stops, check for open wire from EST terminal "E" to ECM. If wire is okay, replace either HEI-EST connector or module. If engine runs, remove jumper wire from terminals "A" and "B" while leaving test light connected. If engine runs, go to step 4. If engine stops, go to step 5.
  4. If engine continued to run in step 3, check distributor wires for open or ground to HEI-EST module terminal "B" or short between module terminals "R" and "E". If wires are okay, repair faulty HEI-EST module connection or replace HEI-EST module.
  5. If engine stopped in step 3, check for correct HEI module. Check for open wire from EST connector terminal "A" to ECM connector terminal "12". Also check for open or grounded wire from EST connector terminal "C" to ECM connector terminal "11". If wires are okay, replace faulty ECM connector or ECM.
NOTE: ECM connector terminal numbers may vary between models.
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