Diagnostic Aids

Using "Scan" tool, check for proper signal in Drive while wiggling wiring. Ensure all connectors are good. Very carefully check the pass-through connector at transmission. If input sensor is not working at start-up, output sensor will read zero. If Code 24 is set in computer memory, "Scan" tool will read engine RPM (input sensor signal).

Fig 1: Output Speed Sensor Diagnostic Flow Chart (1992 2WD)

Courtesy of GENERAL MOTORS CORP.