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Home >> Geo >> 1991 >> Prizm Base, 4D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Tests W/Codes >> PRIZM GSi CODE CHARTS (VIN 5) >> Chart A1, No Check Engine Light

Chart A1, No Check Engine Light

With ignition switch in the ON position and engine off, CHECK ENGINE light should always be on. ECM controls CHECK ENGINE light by completing bulb ground circuit.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. An open GAUGE fuse could indicate a short to ground in GAUGE fuse circuit.
  2. Indicates a ground path through ECM.