Ignition System - HEI-Est (CALIF): Diagnosis

NOTE: Diagnosis of EST systems requires thorough understanding of General Motor's Computer Command Control (CCC) system. Diagnosis chart for Code 42 is provided for technicians with CCC knowledge. Procedure applies to 2.5L (TBI) equipped engines; others are similar. For further information, see GENERAL MOTORS COMPUTER COMMAND CONTROL article in COMPUTERIZED ENGINE CONTROLS section. See Fig 1-8.

Fig 1: Pickup Coil

Fig 2: Spark Tester

Fig 3: Pickup Coil W/Voltmeter Connected

NOTE: Perform Dignostic Circuit Check before using this procedure. If a tachometer is connected to the tachometer terminal, disconnect it before proceeding with the test. Intermittent no start may be caused by wrong pick-up or ignition coil.

Fig 4: Eng. Cranks, But Won't Run, Flow Chart (W/Integral Ign. Coil)

NOTE: Perform Diagnostic Circuit Check before using this procedure. If a tachometer is connected to the tachometer terminal, disconnect it before proceeding with the test. Intermittent no start may be caused by wrong pick-up or ignition coil.

Fig 5: Eng. Cranks, But Won't Run, Flow Chart (W/Integral Ign. Coil)(1 Of 2)

Fig 6: Eng. Cranks, But Won't Run, Flow Chart (W/Integral Ign. Coil)(2 Of 2)

Fig 7: Spark Output Test