Vehicle Speed Sensor (VSS) (Code 24)

1. With ignition on, backprobe VSS connector. VSS is located on transaxle. Battery voltage should exist at Red/White/Black wire. See Fig 1 . Ensure continuity exists between Black/White wire (ground circuit) and chassis ground.
   CAUTION: DO NOT  perform this test without supporting the lower control arms so that drive axles are in a normal horizontal position. Drive axles may be damaged
2. Measure voltage at Brown wire (circuit A10) while turning drive wheels. As Hall Effect switch pulses circuit to ground, voltage should drop toward zero. If voltage does not change, replace VSS.

Fig 1: Checking Vehicle Speed Sensor (VSS) Circuits

Courtesy of GENERAL MOTORS CORP.