LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1986 >> Forward Control 7.4 W, Standard >> Repair and Diagnosis >> Engine Performance >> Tune-Up >> Ignition System - HEI (Federal) >> Component Testing >> External Ignition Coil
September 30: LEMON manuals is back up on a temporary server! Slowness is possible

External Ignition Coil

  1. Connect ohmmeter leads to battery and "TACH" terminals. See Fig 1 . Primary resistance should read approximately zero. Attach leads to battery terminal and ground. An infinite reading indicates coil is okay.
  2. Connect ohmmeter leads to "TACH" and high voltage terminal. Use high resistance scale. If ohmmeter does not indicate below infinite resistance, coil must be replaced. See Fig 1 .
Fig 1: External Coil Test Connection
G9012