B2722

Code

Generic B — Body

Body Control Module Internal Failure

Brand: Generic

Type: B — Body

Views: UK: 4 EN: 3 RU: 2

AI status

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Page language: EN

Causes

BCM internal hardware fault (failed component or board-level damage)
Corroded, loose, or damaged power/ground connections to the BCM
Low or unstable battery voltage / poor charging system
Software corruption or failed firmware update
Water intrusion or physical damage to the BCM housing or connectors
Intermittent or shorted CAN/LIN data bus wiring affecting BCM operation

Symptoms

Illumination failures, interior lights, or exterior lighting not working or intermittent
Door locks, windows, wipers, or other body functions inoperative or erratic
Warning lights on dash related to body systems or security
Loss of communication with BCM on scan tool or intermittent CAN faults
Vehicle may not go into accessory/run states as expected, keyless entry issues

What to check

Connect a capable scan tool and confirm presence of B2722 and any related codes; note freeze-frame and occurrence count
Attempt communication with the BCM; check if ECU responds to scanner
Measure battery voltage with ignition off and on (expect ~12.4–12.8V resting, ~13.5–14.8V charging with engine running)
Inspect fuses and fusible links for BCM power circuits
Visually inspect BCM connectors and harness for corrosion, bent pins, water intrusion, or physical damage
Verify BCM power and ground at the module with a multimeter (see signal parameters below)

Signal parameters

BCM battery supply: near battery voltage (approx. 12.4–12.8 V resting, >13.5 V charging)
Ignition-switched supply: ~12 V with key/ignition ON
Ground continuity:
CAN bus idle levels: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V; active frames CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
Wake/sleep lines or LIN: expected logic levels per vehicle documentation (verify with wiring diagram)
Module diagnostic response: BCM should respond to scan tool queries; lack of response indicates communication or internal fault

Diagnostic algorithm

Record all stored codes, freeze-frame data, and note whether the BCM responds to the scan tool.
Check vehicle battery state of charge and charging system; repair low voltage or charging faults before further diagnosis.
Inspect BCM connectors, wiring harness, and mounting area for corrosion, water intrusion, rodent damage, or physical impact; repair any damage.
Verify power and ground at the BCM connector with a DVOM: power pin(s) should show battery or switched battery voltage; ground pins should have very low resistance to chassis ground.
Check related fuses/relays and backprobe supply circuits while operating affected functions; verify circuits are not open or intermittently losing supply.
Check CAN/LIN bus integrity: with key on, measure CAN_H/CAN_L at the BCM and at least one other module; confirm proper idle voltages and ability to see traffic with a scan tool or scope.
If communication is intermittent, wiggle harnesses and connectors while monitoring live data to reproduce fault and locate intermittent wiring/connector issues.
If power, ground, and communications are good but fault persists, attempt BCM soft reset per manufacturer procedure (battery disconnect or module reset via scan tool) and re-scan.
If reset fails, check for available software updates or reflash/reprogram the BCM using manufacturer-approved tools and procedures.
If reprogramming does not clear the internal fault and all external causes are ruled out, replace the BCM with a correctly programmed unit and perform required module coding/initialization.
After repair, clear codes and perform a full system check and road test to confirm proper operation and no recurrence.

Likely causes

BCM power or ground fault (corrosion, loose terminal)
Software corruption requiring reflash/reset
Water damage or connector corrosion at the BCM
Module internal component failure

Fault status

⚠️ Status

B2722 — Body Control Module Internal Failure: The BCM has detected an internal hardware or software fault. The code may be stored as active when the module self-tests fail or when communication with the module is lost. Intermittent conditions may store the code with occurrence counts; persistent internal failures typically require module repair or replacement after external causes are excluded.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0-3.0 hours