1994 Oldsmobile Ninety-Eight RegencyFACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

An intermittent may be caused by rubbed through wire insulation. Check for:

  • Boost control driver circuit shorted to ground.
  • Intermittent Test

Disconnect PCM Blue connector and install a DVOM to monitor voltage between PCM harness boost control driver circuit terminal and ground. With ignition on, observe voltage while moving related connectors and wiring harness. If failure is induced, voltage reading will change.

Fig 1: Code P1257 Schematic (3.8L) Transmission Shift Solenoid "B"
G94B34729
Factory Service Tools

Use the Manual With the Right Hardware

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

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

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.