Diagnostic Aids

1990 Pontiac Grand Prix STE, 3.1 VSECTION Diagnostic Aids

A problem in circuit No. 434 (auto. trans.) will not affect VSS input or readings displayed by "Scan" tester. Ensure circuits No. 400 and 401 have proper connections. Also check for correct harness routing. If code is intermittent, see INTERMITTENTS in TESTS W/O CODES article.

Fig 1: Code 24: Circuit Diagram (L & N BODIES)
G90D15902
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

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

Affiliate disclosure: We may earn a commission at no extra 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.