Test Description

WARNING: This page is about a different car, the 1995 Oldsmobile Ninety-Eight and 1995 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Test numbers refer to numbers on diagnostic chart.

VSS signal generator only produces a signal if drive wheels are turning greater than 3 MPH.
Check PROM for correct application before replacing PCM.

Fig 1: Codes P0501/P0502 Schematic (3.8L) VSS Circuit

Fig 2: Codes P0501/P0502 Diagnostic Flow Chart (3.8L) VSS Circuit