Code
B144F
LAND ROVER
B — Body
foldable attacker power supply circuit control module - Ignition source of the engine compartment 3
Views:
UK: 3
EN: 9
RU: 3
AI status
Completed
Completed
100%
Causes
- Blown fuse or faulty circuit breaker for the engine-compartment ignition-switched supply
- Faulty ignition relay or ignition switch contact feeding engine-compartment ignition source 3
- Open, corroded, disconnected or damaged wiring or connector between the ignition source and the foldable actuator control module
- Short to ground or to permanent battery voltage on the ignition-switched feed
- Faulty foldable actuator control module (internal power supply or input circuitry)
- Intermittent or poor ground for the control module causing false supply readings
Symptoms
- Foldable actuator(s) (mirrors/antenna/roof component depending on vehicle) not operating or intermittent operation
- Stored body control module / foldable actuator control module DTCs (including B144F)
- Accessory does not power up with ignition in the RUN/ACC position
- Possible parasitic battery drain if the circuit is shorted to battery
- No obvious fault in mechanical components when electrical supply is absent
What to check
- Verify exact component(s) referenced by the code in the vehicle service manual (which foldable actuator and which control module)
- Visually inspect fuses and related relays for the engine-compartment ignition-switched supply #3
- Inspect wiring harness and connectors from ignition source to the control module for damage, corrosion, or poor pin retention
- Check for stored related codes in other modules (body, BCM, IPC) to identify upstream faults
- Measure voltage at the control module power pin with ignition OFF and ON
- Measure resistance/continuity from the control module power pin back to the fuse/relay output
Signal parameters
- Ignition OFF: supply pin ~ 0 V (or battery voltage only if circuit is unintendedly tied to battery — indicates short)
- Ignition ON/RUN or ACC: supply pin expected ~ 11–14.5 V (battery voltage under normal operating conditions)
- Open-circuit: very high resistance / infinite between fuse output and module power pin
- Short-to-ground: near 0 Ω between module power pin and chassis ground
- Short-to-battery: near 0 Ω between module power pin and battery positive (constant feed) when ignition OFF
Diagnostic algorithm
- Retrieve freeze frame and full stored code list from all modules. Note which ignition positions trigger the code.
- Identify exact fuse/relay and wiring harness for ‘engine-compartment ignition source 3’ from the factory wiring diagram.
- Visually inspect the fuse, relay, harness routing and both ends of the connector at the control module for obvious damage, corrosion or loosened pins.
- With a digital multimeter, measure voltage at the control module power pin: verify ~0 V with ignition OFF and ~12–14 V with ignition ON. Record results.
- If voltage is incorrect, test continuity between the control module power pin and the fuse/relay output. Repair any open/high-resistance connections.
- If fuse blows or voltage drops under load, isolate short by disconnecting downstream connectors and rechecking; inspect harness for chafing or pinched wiring.
- Check operation of the related ignition relay and ignition switch feed; substitute a known-good relay if needed and re-test.
- Verify good ground(s) for the control module — measure voltage drop while operating the circuit.
- If wiring and external components test good, follow manufacturer procedure to test or replace the foldable actuator control module. Reprogram/initialize if required after replacement.
- Clear codes and confirm proper operation through multiple ignition cycles and functional tests; perform a wiggle/intermittency test to ensure repair is successful.
Likely causes
- Blown fuse protecting the engine-compartment ignition source 3
- Loose or corroded connector at the control module power pin
- Damaged harness (chafing, rodent damage) in engine bay where wiring routes
- Failed ignition relay or degraded ignition switch contact
- Control module internal failure
Fault status
Status
B144F — Foldable actuator power supply circuit (control module) — Engine compartment ignition source 3: expected ignition-switched feed missing, shorted, open or intermittent.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
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Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
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Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
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Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
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