B2390

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 15 EN: 24 RU: 14

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Internal BCM hardware failure (processor, memory, I/O)
Corrupted or failed BCM software/firmware
Loss or interruption of BCM power or ground (intermittent low voltage)
Water intrusion, corrosion or physical damage to BCM or connector
Failed internal EEPROM/flash memory or checksum error
CAN/LIN bus communication errors or bus transceiver failure

Symptoms

Multiple body electrical functions intermittent or inoperative (lights, wipers, locks, windows, HVAC doors)
Warning lamp(s) or message(s) on dash related to body systems or module fault
Keyless entry, alarm or immobilizer issues
Intermittent loss of vehicle features tied to BCM control
Possible excessive battery drain if outputs stuck on
Difficulty programming or communicating with BCM via scan tool

What to check

Retrieve freeze-frame and full DTC list with a capable scan tool; note related U/P/C codes
Check vehicle battery voltage (at rest and during cranking) and battery connections
Inspect BCM area for water intrusion, corrosion, or physical damage
Verify BCM fuses and fusible links are intact and properly seated
Visually inspect BCM connectors and wiring harness for damaged pins, corrosion, or loose terminals
Check for other modules reporting communication faults on CAN/LIN bus

Signal parameters

Battery supply voltage to BCM: nominal 12.4–13.2 V (engine off) and 13.5–14.8 V (engine running)
Ground resistance:
CAN bus physical layer: differential idle voltage ~2.5 V, CANH/CANL normally ~2.5 V each (check against vehicle spec)
LIN bus wake and response frames present when controller is woken (timing and voltages per vehicle)
Internal diagnostic self-test/EEPROM checksum status (scan-tool reported)
Watchdog reset counters or internal reboot count (if available in module data)

Diagnostic algorithm

Record all stored DTCs and freeze-frame data; also read related U/P/C codes from other modules.
Verify battery state of charge and clean battery terminals; retest with fully charged battery.
Perform a visual inspection of BCM, mounting, and harness; look for water intrusion, corrosion, or physical damage.
Check BCM power and ground circuits: verify battery feed and ground continuity/voltage at the module connector with ignition off and key-on.
Verify BCM fuses and fusible links; replace if blown and investigate cause of blown fuse before continuing.
Attempt to communicate with BCM using a manufacturer-capable scan tool; note failure modes (no response, intermittent, corrupted data).
If communication issues exist, isolate the CAN/LIN bus: check bus voltages, short to battery/ground, and continuity to other modules. Repair wiring faults if found.
If power/ground and bus are OK but internal faults persist, attempt to recover module per manufacturer procedure: soft reset/power cycle and reflash/reprogram firmware if update available and advised.
If reflashing fails or module reports persistent internal errors, prepare for BCM replacement and reprogramming; document original module coding and immobilizer pairing requirements before replacement.
After repair/replacement, clear codes and verify all body systems and communications are restored; road test to confirm intermittent faults are resolved.

Likely causes

Battery low/poor battery connections causing module brown-out
Loose, corroded or damaged BCM power or ground connector pins
Blown BCM fuse(s) or fusible link feeding the BCM
Damaged CAN/LIN wiring or short to power/ground on the network
Internal memory corruption due to failed EEPROM/flash
Prior unsuccessful reflash or wrong calibration loaded

Fault status

⚠️ Status

Internal fault detected in Body Control Module. Module self-test or memory checksum failed, or module is non-responsive to diagnostic communications. Further investigation of power, ground, and communication bus required; reprogramming or replacement may be necessary.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.5-4.0 hours