The most reliable, efficient, and accurate means to diagnose the power lock system requires the use of a scan tool and the proper Diagnostic Procedures manual.Refer to the appropriate wiring information.Make certain battery is in normal condition and fuses powering the RKE module aren't blown before circuits are tested.To determine which motor is inoperative, check each individual door for electrical lock and unlock or disconnect the motor connectors one at a time, while operating the door lock switch.In the event that none of the motors work, the problem maybe caused by a shorted motor, a bad switch or a bad relay internal to the RKE module. Disconnecting a defective motor will allow the others to work.To test an individual door lock motor, disconnect the electrical connector from the motor.To lock the door, connect a 12 volt power source to one pin of the lock motor and a ground wire to the other pin.To unlock the door, reverse the wire connections at the motor pin terminals.If these results are NOT obtained, replace the motor.