B2992

Code

Generic B — Body

Body Control Module Internal Fault (B2992)

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 12 RU: 18

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

BCM internal hardware failure (processor, memory, internal power regulator)
Corrupted or failed BCM software/firmware
Low or unstable vehicle battery/charging system voltage during module operation or programming
Poor power or ground connections to the BCM (corrosion, loose connector, broken wire)
Faulty or shorted modules or accessories on the same network causing bus errors
Water intrusion or physical damage to BCM

Symptoms

Multiple body systems inoperative or behaving erratically (lights, locks, windows, wipers)
Warning lamps illuminate (CAN/communication warnings, lamp failures)
Intermittent or permanent loss of communication with BCM on diagnostic tool
Stored multiple unrelated body-related DTCs
Vehicle may enter limp or restricted functionality for body features

What to check

Read all stored codes and freeze frame data with a capable scan tool; note related U-codes
Verify battery voltage and state of charge (key ON, engine OFF) — should be within manufacturer spec (typically 12.2–13.0 V at rest; >13.5 V with engine running)
Inspect BCM connector for corrosion, bent pins, water intrusion, or damage
Check power and ground circuits for proper continuity and low resistance to chassis/ battery negative
Scan network for communication faults (U0100/U0121 or similar) and verify CAN/LIN bus integrity
Attempt to clear code and re-test; see if code returns immediately or intermittently

Signal parameters

VBATT to BCM key-on: typically 12–14.5 V (refer to vehicle spec)
VBATT to BCM during cranking: should not drop below manufacturer threshold (varies by vehicle)
CAN High/Low idle voltages: approx. 2.5 V common mode; differential ~60–120 mV idle
Wake/sleep control signal states as specified by manufacturer (0/12 V or LIN protocol)
Module supply and internal reference voltages per OEM test data (requires factory documentation)

Diagnostic algorithm

Use a full-function scan tool to record B2992 plus any other stored DTCs and freeze frame data.
Confirm battery condition and charging system; charge battery or connect a stable power supply if low.
Visually inspect BCM connector and harness for corrosion, water, damaged insulation, or pin damage; repair as needed.
Verify BCM power and ground circuits: measure voltage at BCM connector (key ON) and check ground resistance to chassis (
Check network communication: monitor CAN/LIN traffic with scope or advanced scan tool. Look for bus faults, stuck dominant, or noise.
If connector, power/ground, and bus are good, attempt to clear codes and cycle ignition; if code immediately returns, note behavior.
Check for available software updates or reflash procedures from manufacturer; perform reprogram/reload per OEM instructions while maintaining stable battery voltage.
If reflash fails or errors occur during programming, suspect internal BCM failure. Confirm with manufacturer diagnostics or bench testing service if available.
If replacement BCM is required, ensure proper part number, VIN-specific programming, and complete all required coding/relearn procedures after install.
After repair or replacement, verify all previously stored codes are cleared and perform full system test for affected functions.

Likely causes

Corroded BCM connector or pin
Battery drained or weak while module was active or during last flash
Intermittent supply/ground causing memory corruption
Failed internal voltage regulator or clock in BCM
Failed BCM after an attempted software update

Fault status

⚠️ Status

Body Control Module internal fault detected. Module internal self-test failed or internal memory/firmware error present. Module may require reprogramming or replacement after verifying power, ground, and network integrity.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.5-4.0 hours