B10AF

Code

LAND ROVER B — Body

Relay of fan of the fan

Brand: LAND ROVER

Type: B — Body

Views: UK: 15 EN: 24 RU: 19

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Failed or sticking fan relay
Blown fuse protecting the fan relay circuit
Open, shorted or corroded wiring/connector in relay feed or control circuit
Poor ground at relay or fan motor
Faulty cooling/auxiliary fan motor
Body control module (BCM) or engine control module (ECM) driver fault or software issue

Symptoms

Radiator/cooling fan does not operate when commanded
Reduced air‑conditioning cooling at low speeds/idle
Engine operating temperature higher than normal or overheating
Cooling fan runs continuously or intermittently
DTC stored and possibly a dash message about cooling system or fan

What to check

Read and record trouble codes and freeze-frame data with a diagnostic scanner
Visually inspect fan relay, associated fuse, wiring harnesses and connectors for damage, corrosion or water
Check fuse continuity and proper seating
Listen for relay click when fan is commanded; test relay operation by swapping with identical known-good relay if available
Measure battery voltage at relay power terminal and ground continuity
Command fan ON with diagnostic tool and verify relay activation and fan operation

Signal parameters

Battery supply at relay feed: ~12 V (engine off) to ~13.5–14.5 V (engine running)
Control signal from BCM/ECM: On/off or PWM ground/12 V signal when fan commanded (0–12 V, PWM duty varies 0–100%)
Relay coil resistance (typical): tens to hundreds of ohms (varies by relay type)
Fan motor resistance: low ohms (depends on motor); stalled motor will show near‑zero rotation and high current draw
Expected fan current draw: typically several amps (varies by vehicle); excessive current indicates motor mechanical/electrical fault

Diagnostic algorithm

Connect a diagnostic scanner, read and record code B10AF and any related codes; note freeze-frame data and conditions when code set.
Visually inspect relay, fuse, relay socket and wiring for damage, corrosion or loose connections. Repair any obvious issues.
Verify fuse continuity and correct fuse rating; replace if blown.
With ignition ON, command the cooling fan ON using a scan tool and listen for relay click. If relay does not click, probe relay coil terminals for control signal.
Check for battery voltage on the relay power feed terminal and good ground on relay ground terminal.
If control signal is present but relay does not activate, remove relay and bench-test or replace the relay. Retest operation.
If relay activates but fan does not run, measure voltage at fan motor connector while commanded. If voltage present but fan does not run, test fan motor directly with battery while observing current draw.
If no control signal from BCM/ECM, check wiring continuity between module and relay socket and inspect for shorts to battery or ground. Repair as required.
After repairs, clear codes, perform functional tests and road/idle test to confirm fan operation and monitor for reoccurrence.
If wiring and hardware are good but fault persists, consider module diagnostic/repair or software update per manufacturer guidance.

Likely causes

Faulty fan relay
Blown fuse or poor fuse contact
Corroded/loose connector at relay or fan
Open/short in relay control circuit
Fan motor failure or high current draw

Fault status

⚠️ Status

Fan relay circuit fault recorded by vehicle control module. Possible relay, wiring, fuse, fan motor or module driver issue causing incorrect fan operation.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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