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.
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HOMESERVICE MANUALSCHEVROLET2003MALIBU V6-3.1L VIN JREPAIR AND DIAGNOSISRELAYS AND MODULESRELAYS AND MODULES - POWERTRAIN MANAGEMENTRELAYS AND MODULES - COMPUTERS AND CONTROL SYSTEMSBODY CONTROL MODULEDESCRIPTION AND OPERATION
2003 Chevrolet Malibu V6-3.1L VIN J
Body Control Module: Description and Operation
2003 Chevrolet Malibu V6-3.1L VIN JSECTION Description and Operation
BODY CONTROL MODULE (BCM)
The BCM contains the logic of the theft deterrent system. The BCM provides the battery positive voltage to operate the Passlock(TM) Sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock(TM) Sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the PCM. If the voltage codes do not match, or the voltage is in the Tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.
The BCM contains the logic of the theft deterrent system. The BCM provides the battery positive voltage to operate the Passlock(TM) Sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock(TM) Sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the PCM. If the voltage codes do not match, or the voltage is in the Tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.