B3200

Code

Generic B — Body

Body Control Module Power Supply Fault

Brand: Generic

Type: B — Body

Views: UK: 14 EN: 13 RU: 10

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Causes

Blown or corroded main BCM fuse or fusible link
Poor battery condition or low system voltage
Open, short, or high-resistance wiring in BCM power or ground circuits
Corroded, loose or damaged BCM connector
Accessory or ignition relay fault supplying the BCM
Internal BCM power regulator or circuitry failure

Symptoms

Multiple body electrical features inoperative or intermittent (lights, locks, wipers, windows)
Instrument cluster or message center warnings related to BCM
Modules losing communication or U-codes (CAN bus) present
Vehicle may not go to sleep or may have abnormal battery drain
No crank/immobilizer issues if BCM controls starter enable

What to check

Check battery state of charge and surface voltage (key off and key on/start)
Inspect BCM-related fuses, fusible links and relays for continuity and correct rating
Visually inspect BCM connector for corrosion, bent pins, water, or damage
Check major ground points and measure ground resistance to chassis (
Use scan tool: read BCM codes, freeze frame, and module power/input data
Measure supply voltage at BCM power pins (key off, key on, engine running)

Signal parameters

Battery resting voltage (key off): typically 12.4–12.8 V (good charge)
Cranking voltage: should not drop below ~9–10 V under load (vehicle-dependent)
Operating system voltage (engine running): ~13.5–14.8 V
BCM primary power pin: near battery voltage with key off or as specified by wiring diagram
Ground resistance from BCM ground to battery negative: ideally
Expected BCM sleep current: typically

Diagnostic algorithm

Verify DTC: connect a capable scan tool and retrieve DTCs and freeze-frame data. Note related U/P codes.
Battery health: check battery voltage and conductance/test battery with load tester. Recharge or replace if weak.
Fuses/relays: visually inspect and measure continuity of BCM main fuses, fusible links and relays. Replace any blown or high-resistance items.
Visual inspection: examine BCM and harness connectors for corrosion, water ingress, damaged seal, bent pins, or recent repairs.
Power pin check: with appropriate safety, backprobe BCM power pin(s) and measure voltage with key off, key on, and engine running. Compare to expected values.
Ground check: measure voltage drop between BCM ground and battery negative while operating loads; verify ground continuity and clean/repair ground connections as needed.
Wiggle test & load test: with scan tool monitoring, wiggle harness and apply loads to reproduce fault; check for intermittent voltage loss.
Parasitic draw: if battery drains, perform parasitic current test isolating fuses to find source; disconnect aftermarket accessories as a test.
Repair wiring/connectors: repair any open/short/high resistance circuits, replace corroded connectors, and reinstall secure fasteners.
Re-test: clear codes, restore power, and retest vehicle across expected operating conditions (key cycles, sleep/wake, engine start) to confirm the fault does not return.
Module replacement: only consider BCM replacement after verifying power/ground and harness integrity. Follow OEM programming/initialization procedures if control module is replaced.
Safety note: isolate battery when performing major wiring repairs and follow vehicle-specific safe procedures for SRS/airbag and electrical systems.