B2512

Code

LAND ROVER B — Body

Fog light relay circuit - short circuit to the battery

Brand: LAND ROVER

Type: B — Body

Views: UK: 13 EN: 17 RU: 17

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Page language: EN

Causes

Short to battery (B+) on fog lamp relay feed or control wire
Faulty/shorted fog light relay
Chafed or pinched wiring harness contacting a positive conductor
Aftermarket fog lamps or wiring incorrectly tied to battery
Corroded or damaged connector supplying the relay
Internal short in body control module/BCM (less common)

Symptoms

Fog lamps remain on continuously or operate without switch
Blown fog lamp fuse(s) or repeated fuse failures
Parasite battery drain when vehicle is off
Loss of proper fog lamp switching control
Possible diagnostic trouble code stored in body/BCM

What to check

Scan BCM for B2512 and related codes; record freeze frame or status bits
Visually inspect fog lamp relay, fuse, relay socket and associated wiring harness
Remove the fog lamp relay and see if lamps or symptoms persist
Check related fuses for continuity and signs of melting or corrosion
Measure voltage at relay socket terminals with ignition OFF and ON
Perform a pin-to-pin continuity/short-to-battery check between suspect circuit and battery + with ignition off

Signal parameters

Battery/relay supply terminal: ~12.6 V (engine off), ~13.5–14.5 V (engine running)
Relay control terminal: ~0 V when OFF; ~battery voltage when relay commanded ON
Relay coil resistance: typically tens to low hundreds of ohms (varies by relay) — a near-zero resistance suggests an internal short
Fuse current: should be below rated fuse trip; repeated fuse blow indicates short/high fault current

Diagnostic algorithm

Retrieve and note any additional codes and freeze-frame data from the BCM. Verify B2512 is current and releasable.
With ignition OFF, disconnect the fog lamp relay. Confirm whether fog lamps go out and whether any loads or drains stop. If lamps remain on with relay removed, the short is downstream or tied directly to battery.
Inspect wiring visually along harness runs (especially near body panels, bumper and engine bay) for chafing, pinches, or exposed conductors that could contact a positive source.
Remove fuse for fog lamp circuit. If fuse was blown, replace with a new fuse of correct rating and perform a bench test: with fuse installed, measure current to detect short. If fuse blows immediately, isolate by disconnecting loads (lamps, relay sockets) until fuse holds.
With battery negative disconnected for safety, use an ohmmeter to check continuity between the fog lamp circuit and battery positive. A direct short will show very low resistance.
Reconnect battery and backprobe relay socket: with switch OFF expect 0 V at control; if battery voltage present at control when off, trace back to connector/BCM output. Wiggle harness while monitoring to find intermittent shorts.
Swap relay with a known-good identical relay (if available) and re-test. If problem persists, disconnect fog lamp connectors one at a time to locate the shorted branch.
Inspect and remove any aftermarket wiring; repair damaged wiring or replace connectors/harness sections. If BCM output is suspected after isolating harness and loads, consult OEM wiring diagrams and consider module bench test or replacement.
After repair, clear codes, operate fog lamps through full function cycles and monitor for return of fault. Road test and re-scan to confirm repair.

Likely causes

Relay coil or relay internal contact welded/shorted to B+
Supply or switched feed wire insulated damage contacting battery positive or fused feed
Aftermarket accessory tied directly to constant battery supply on fog lamp circuit
Connector corrosion allowing feed to bridge to control terminal
Damaged BCM output stage allowing battery voltage onto circuit

Fault status

⚠️ Status

Short to battery detected on fog light relay circuit. Fault stored by body control module (BCM). May cause lights to remain on, fuses to blow or battery drain.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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B2512 — Fog light relay circuit - short circuit to the battery