The body control module for your 2000 Chevrolet Impala is responsible for handling the vehicle's lighting, retained accessory power, audible reminders, door locks and several other electronically controlled systems, including the Passlock theft deterrent feature. In order to start the vehicle's engine, the Passlock sensor – located inside of the ignition lock cylinder – must provide the BCM with an analog “passcode,” which is essentially an expected, pre-learned voltage value. If the BCM receives a different voltage than expected, the powertrain control module will disable the fuel system. After replacing the BCM, PCM or ignition lock cylinder, you must perform the Passlock relearn procedure.
Open the hood and disconnect the protective red cap – located to the left of the engine compartment's power distribution box – from the remote positive battery stud. Connect the positive cable from the trickle charger to the remote positive battery stud, then connect the negative charger cable to the negative battery post, or a suitable grounding point, such as the passenger-side engine compartment brace above the battery.
Connect the charger's power cord, then activate the charger according to the product's instructions. Turn off any unnecessary vehicle accessories, such as the interior lighting, climate controls and radio.
Switch the ignition to the “On” position, then momentarily turn the key to the “Start” position; release the key. Allow the ignition switch to remain in the “On” position for approximately 10 minutes. When the “Security” light on the gauge cluster turns off, switch the ignition to the “Off” position for five seconds.
Repeat the previous step two additional times. After switching off the ignition for the third and final cycle, attempt to start the engine. If the engine fails to start after the third cycle, repeat the relearn procedure.
Disconnect the battery charger and replace the battery stud cap. Connect the OBDII code reader to the vehicle's on-board diagnostic port – located to the bottom right of the steering column – and erase the codes associated with the theft deterrent system, according to the product's instructions.
