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Home >> Buick >> 1980 >> Skyhawk Base, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Electronic Spark Control & Electronic Module Retard Ignition System >> Testing >> Electronic Module Retard >> With C4 System
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With C4 System

  1. Start engine and idle until normal operating temperature is reached. Check ignition timing then disconnect EMR lead at distributor.
  2. If timing does not change, proceed to step  4). If timing advances, connect a test light from battery positive terminal to EMR lead going to Electronic Control Module (ECM).
  3. If test light does not come on, replace ECM. If test light does come on, disconnect connector from ECM. If test light goes out, replace ECM. If light stays on, repair ground lead in EMR.
  4. If timing did not change when EMR lead was disconnected, ground distributor side of EMR lead. If timing now retards the trouble is not in the EMR circuit.
  5. If timing does not change, check for open or grounded EMR lead to distributor. If lead is OK, replace EMR module.
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