1990 Pontiac LeMans BaseFACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

Scan should indicate a vehicle speed whenever drive wheels are turning greater than 3 MPH. A faulty or misadjusted park/neutral switch can result in a false Code 24. Use Scan tester to check for properly adjusted Park/Neutral switch in "D", "P" and "N". For additional information and testing of park/neutral switch see ENGINE SENSORS & SWITCHES in I - SYS/COMP TESTS article. If Code 24 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.

Fig 1: Circuit Diagram Chart Code 24
G90C15547Courtesy 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.

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.