Code 24, Vehicle Speed Sensor - 4WD With 4L80-E Transmission: Notes

1992 GMC Rally G1500, 4.3 ZSECTION Notes
Fig 1: Code 24, VSS Circuit Diagram (4WD With 4L80-E Transmission)
G91G13736Courtesy of GENERAL MOTORS CORP.

VSS output sensor is a magnetic induction type. Gear teeth pressed on the outside diameter of the output carrier assembly induce an alternating current in the sensor when drive wheels are turning. Since vehicle speed is taken from the transfer case on 4WD vehicles, output speed sensor signal on these units goes directly to PCM. Code 24 will set if gear selector is not in Park or Neutral, engine speed is at least 3000 RPM and output speed is less than 200 RPM for at lease 1.5 seconds.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Test verifies VSS voltage at PCM.
  2. Test verifies VSS signal at sensor.
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.