Alternate Test Using Kent Moore Tool J38522

^ Connect a Scan Tool to the ALDL connector. Disconnect the Vehicle Speed Sensor connector. Connect a lead between the J-38522 vehicle speed generator's red output terminal and the Vehicle Speed Sensor connector terminal A (YEL). Connect a lead between the J-38522 generator's black output terminal B (PPL). Plug the generator into the Cigar Lighter. Select 30V P-P sine wave and set the frequency at 600 Hz. Observe the Speedometer and compare to the vehicle speed shown on the Scan Tool.
^ If both the Speedometer and Scan Tool display the same approximate speed, check the ECM MEM-CAL, the Vehicle Speed Sensor, and for the correct tire size.
^ If the Scan Tool and Speedometer do not display the same approximate speed, service the Instrument Cluster.