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Home >> Pontiac >> 1989 >> Safari >> Repair and Diagnosis >> Engine Performance >> Ignition System - HEI-Est >> Testing >> Intermittent Operation Check

Intermittent Operation Check

  1. Check fuel system, spark plug wires, distributor cap, and spark plugs. Most intermittent problems are caused by faulty electrical connections. Visually inspect wiring for a fault. Drive vehicle with a voltmeter connected to a suspected circuit.
  2. Using a "Scan" tester, monitor input signals. See SCAN TESTER USAGE and SCAN DATA tables in appropriate THEORY & OPERATION article in the ENGINE PERFORMANCE section. Check for electrical system interference caused by a defective relay, ECM driven solenoid or switch causing a sharp electrical surge. Problem should occur when faulty component is operated. If problem ceases when component is disconnected, component is at fault.
  3. Check for proper HEI distributor ground circuit. Check for improper installation of electrical options such as lights, radios, etc. Check for open diode(s) across A/C compressor clutch and other possible defective diodes.
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