Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Description & Operation
The Body Control Module (BCM) performs the following functions: Remote Keyless Entry (RKE), Universal Theft Deterrent (UTD) system, Personalized Automotive Security System (PASS-Key II(R)), chime, fasten seat belt indicator, low coolant indicator latching, retained accessory power, power door locks, rear compartment lid release, courtesy light control, illuminated entry, and delayed interior lights.
Signals that activate the BCM are known as "wake-up" signals. BCM is asleep when it is not controlling or monitoring the following wake-up functions: courtesy light system, remote keyless entry system, ignition on (IGN 1), parking lights, headlights, door jamb switches, rear compartment lid ajar indicator switch, key-in-ignition switch, and shock sensor inputs. When BCM is awake and wake-up signal is removed, after 10 minutes, BCM will return to sleep. If BCM receives a door ajar wake-up signal and wake-up remains active after 10 minutes, BCM will turn off courtesy light (if illuminated) to prevent battery drain.
BCM battery terminals operating current should not exceed 75 milliamps while BCM is awake with ignition off. An approximate normal value with ignition switch in RUN position is 250 milliamps. If retained accessory power is active, amperage may be higher. Retained accessory power allows operation of power door locks, convertible top and radio until a door is opened, or 10 minutes have elapsed. When BCM is asleep, current should not exceed 2 milliamps (without theft deterrent system) or 3 milliamps (with theft deterrent system). BCM will go to sleep after ignition is turned off and 10 minutes has elapsed. BCM IGN 1 and IGN 3 terminals operating current should not exceed 15 milliamps. Most BCM functions will properly operate with a system voltage of 9-16 volts.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.