4WD With 4L80-E Transmission

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 1992 Oldsmobile Bravada, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Sonoma. However, it is still accessible from the selected car via links, so may be relevant.

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 least 1.5 seconds.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test verifies VSS voltage at PCM.
Test verifies VSS signal at sensor.