B0499

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 6 EN: 6 RU: 6

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Page language: EN

Multiple body functions inoperative or intermittent (locks, lights, windows, wipers, HVAC blower control)
Warning lights or erratic instrument cluster behavior
Inability to communicate with the BCM via diagnostic tool or frequent communication faults
Unexpected module resets or self-test fault messages
Parasitic battery drain or fuse failures
Keyless entry / immobilizer anomalies

Read all stored and pending DTCs and freeze frame data from the BCM and related modules
Verify battery voltage and charging system (resting and cranking voltage)
Inspect BCM connectors and harness for corrosion, water intrusion, bent pins or damaged wires
Check BCM power feeds, ignition-switched supplies and all related fuses/relays
Verify solid chassis and battery grounds at BCM (measure resistance and voltage drop)
Scan vehicle communication buses for errors (CAN/LIN) and other module faults

Supply voltage at BCM connector: typically ~11–15 V (vehicle off vs running differences)
Ground integrity: low resistance to chassis (goal < 0.5–1.0 Ω) and minimal voltage drop during cranking
CAN bus idle voltages: CAN High/CAN Low ~2.5 V each (differential ~0 V idle) and visible traffic when awake
LIN bus idle/wake behavior as specified by manufacturer (wake pulses present when commanded)
BCM wake/sleep input signal states (ignition, wake lines) per service data
Module current draw in sleep and active modes (check for abnormal drain)

Connect a capable scan tool and record all BCM and network-related codes, freeze frame, module info and software version.
Verify battery state of charge and charging system; ensure stable supply voltage before proceeding.
Visually inspect BCM and harness for contamination, corrosion, physical damage and secure connector mating.
Check fuses and relays feeding the BCM circuits; verify power/ignition feeds at the BCM connector pins.
Measure ground resistance and perform voltage-drop tests on ground and power circuits while operating affected functions.
Monitor CAN/LIN communication with a scanner or oscilloscope; confirm bus integrity and that other modules communicate normally.
Clear codes and attempt to reproduce; note whether fault is permanent or intermittent and any conditions that trigger it.
If communication is present, check for available software/firmware updates or reflash/repair procedures from the manufacturer.
If firmware reflash fails or the module remains internally faulted, perform module bench test or swap with a known-good unit (if available) to confirm behavior.
If BCM is confirmed defective, replace with correct part and perform required programming, configuration and security/immobilizer pairing per manufacturer procedures, then retest all functions.