B1C25

Code

Generic B — Body

Body Control Module Circuit C25 Short to Battery

Brand: Generic

Type: B — Body

Views: UK: 5 EN: 11 RU: 10

AI status

Completed

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Page language: EN

Causes

Damaged or chafed wiring making unintended contact with battery positive or a hot feed
Corroded or bridged connector terminals at the BCM or harness connector
Failed component on the C25 circuit internally shorted to battery
Water intrusion or contamination creating conductive path to battery voltage
Poorly installed or faulty aftermarket accessory tied into the same circuit
Internal BCM failure (power transistor or driver shorted)

Symptoms

Affected loads (lights, locks, relays, modules) operate continuously or at wrong times
Parasitic battery drain with vehicle off
Blown fuse(s) on the C25 circuit
BCM-related warning lights or communication errors
Erratic or nonfunctional convenience features controlled by the BCM

What to check

Retrieve stored codes and freeze frame data with a scan tool; record conditions when code set
Visual inspection of wiring harnesses and connectors for damage, melting, or corrosion
Inspect for aftermarket accessories connected to same circuit; temporarily disconnect them
Check fuses and fusible links for the circuit and note any that are blown
Back-probe the C25 circuit with ignition off and on to verify unexpected battery voltage
Measure parasitic draw on battery with all doors closed and key out; note any excessive current

Signal parameters

Expected: ~0 V on C25 with circuit off (no battery feed) or low impedance to ground when commanded
Active: ~12–14.5 V when circuit intentionally fed (ignition on or relay energized)
Fault condition: ~12 V present on C25 when it should be 0 V (short-to-battery)
Parasitic current: typically tens of milliamps up to several amps depending on load; sustained high current suggests a short

Diagnostic algorithm

Safety: record vehicle state, disable affected circuits if needed, and take battery safety precautions. Use insulated tools.
Scan and document: read all BCM and network codes, note when code sets (key on, off, running).
Visual: inspect wiring harnesses along known routing for C25 (doors, kick panels, engine bay) for abrasion or pinched insulation.
Fuse check: identify and inspect related fuses/fusible links. If repeated fuse blows occur, isolate downstream loads.
Voltage check: with ignition off, back-probe C25 at BCM connector. If ~12 V present, short to battery exists in harness or BCM.
Isolate loads: disconnect connectors for devices on C25 one at a time (locks, lamps, relays) while monitoring voltage/current to find which removal clears the condition.
Wiggle and continuity tests: wiggle harness while monitoring for intermittent changes. Check continuity between C25 and battery positive; check for unintended continuity to battery via other circuits.
Remove suspect sections: if a specific harness section is suspected, disconnect and inspect inside grommets, boots, and service holes.
BCM check: if harness and loads isolated and short remains at BCM connector pin, suspect internal BCM short. Confirm by substituting known-good BCM or bench-testing if available.
Repair and verify: repair or replace damaged wiring/connectors, remove corrosion, secure harness routing, replace failed load or BCM as required. Clear codes and verify no reoccurrence through function checks and a soak test.

Likely causes

Shorted wire where the harness contacts a chassis or engine component
Connector corrosion at BCM or at an end device causing battery feed to backfeed
Accessory or module on C25 stuck closed (relay, switch or solenoid) and feeding battery
BCM output stage failed shorted to battery

Fault status

⚠️ Status

BCM reports Circuit C25 shorted to battery (unexpected battery voltage on C25). May cause continuous operation of loads, fuse failure, or battery drain.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours