Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use Scan tester and check for proper signal in Drive, while wiggling shifter. Scan tester MPH reading should closely match speedometer when vehicle is moving.

Fig 1: Code 24, Vehicle Speed Sensor Troubleshooting Chart (3.1L)

Courtesy of GENERAL MOTORS CORP.