Diagnostic Aids

1994 Chevrolet Lumina BaseSECTION Diagnostic Aids

Check all connections to transaxle pass-through connector. An open in the ignition feed circuit will cause multiple codes to set. If scan tester indicates TCC is working, road test vehicle. If engine RPM does not decrease when TCC engagement is indicated on TCC, diagnose transaxle for possible mechanical problem.

Fig 1: Code 740, TCC Circuit Schematic (3.1L "A")
G94E38558Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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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.