B0700

Code

Generic B — Body

Body Control Module — Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 18 EN: 42 RU: 16

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Page language: EN

Causes

Internal BCM hardware failure (processor, memory, voltage regulator)
Corrupted or failed BCM firmware
Power surge or improper jump-start
Water intrusion or physical damage to BCM
Low or unstable battery/charging system voltage
Faulty ground or power supply connections

Symptoms

One or more body systems inoperative or intermittent (lights, door locks, wipers, HVAC blower, etc.)
Interior/exterior lighting or convenience features work sporadically
Remote keyless entry, alarm, or immobilizer issues
Unexpected battery drain or no-go condition for accessories
Multiple related DTCs for body circuits or communication errors
Possible module not responding to scan tool or failing to wake/sleep correctly

What to check

Read and record all stored DTCs, freeze frame, and occurrence counts with a capable scan tool
Check battery state-of-charge and charging system voltage (should be ~12.6 V at rest, ~13.5–14.8 V running)
Inspect BCM connector and wiring for corrosion, bent pins, water ingress, or physical damage
Verify fuses, fusible links, and BCM power/ground circuits for continuity and secure connections
Scan for related CAN/LIN communication trouble codes and check bus activity
Check for recent service events (jump-start, collision, battery replacement) that could cause a power surge

Signal parameters

BCM battery supply pin voltage (key off / key on)
BCM ground impedance
Wake/sleep request signals and their logic levels
CAN bus recessive/dominant voltages and packet activity on CAN high/low
LIN bus frame timing and levels (if applicable)
Internal watchdog reset counters and internal error/status flags (from scan tool)

Diagnostic algorithm

Safely record vehicle info and all codes: use a full-function scan tool to capture DTCs, freeze frame, and module status. Note occurrence history.
Check vehicle power: verify battery voltage and charging system. Reproduce condition while monitoring voltage for drops or spikes.
Visual inspection: remove access cover and inspect BCM and connector for moisture, corrosion, burnt components, or damage. Repair wiring/connector issues as needed.
Verify primary power and grounds at the BCM: back-probe or measure continuity to battery and chassis ground. Repair poor connections.
Check communication: confirm CAN/LIN bus activity using scan tool or oscilloscope. Repair bus wiring, termination resistors, or shorted nodes if faults present.
Use scan tool bi-directional tests: command outputs (relays, lamps, locks) where supported to identify failing outputs or shorted circuits.
If suspect firmware corruption or recurring internal errors, attempt reprogram/reflash BCM software per manufacturer procedure. Ensure stable battery voltage and follow reflash precautions.
Clear codes and re-evaluate: if B0700 returns immediately or after minimal operation, consider BCM replacement. Before replacement, attempt to isolate external cause (shorted output, recurring power events).
If module replacement required: install new/replacement BCM, program vehicle-specific calibration and security data, then retest all affected systems and clear codes.
If intermittent or complex, escalate to manufacturer technical service for advanced diagnostics (internal module bench testing or component-level repair).