1989 Geo Spectrum 2D Hatchback, AutomaticFACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

An intermittent may be caused by rubbed through insulation or a wire broken inside the wire insulation. Check ECM harness connectors for backed out or damaged terminals. If code is intermittent, see TESTS W/O CODES article.

Fig 1: Code 12, Circuit Wiring Diagram & Flow Chart
G121663Courtesy of GENERAL MOTORS CORP.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.