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Home / DTC / B240A — FR antenna(outdoor) open

B240A — FR antenna(outdoor) open

Detailed page for trouble code B240A.

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Code

B240A

MITSUBISHI B — Body

FR antenna(outdoor) open

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Broken or disconnected antenna mast/element
  • Corroded or loose antenna connector or coaxial connector
  • Open wiring or broken coax between antenna and head unit/amplifier
  • Failed antenna motor or mast (on motorized antennas)
  • Failed antenna amplifier (if equipped) or blown antenna power fuse
  • Faulty head unit or body ECU reporting/input circuit

Symptoms

  • Poor or no AM/FM radio reception from front/outdoor antenna
  • Intermittent reception or loss of signal when steering or roof position changes (motorized mast)
  • Radio displays antenna error, or external antenna does not extend (if motorized)
  • Possible related messages in infotainment (loss of antenna diversity)

What to check

  • Confirm customer complaint and attempt to reproduce symptom with radio on and various stations
  • Scan vehicle for related radio/body network codes and note freeze frame or history
  • Perform visual inspection of antenna mast, base, and visible coax for damage or corrosion
  • Inspect connector at antenna base and the head unit antenna input for corrosion, loose pins, or water intrusion
  • Check antenna fuse(s) and power supply circuit (if antenna amplifier/motorized)
  • Measure continuity of coax shield and center conductor between head unit connector and antenna base

Signal parameters

  • Antenna feed voltage: when equipped with powered amplifier/motor, expect battery or switched supply voltage at the antenna power lead when radio is on (typically ignition-switched 12V)
  • Coax continuity: center conductor and shield should show continuity from head unit to antenna (near 0 ohms for short harness lengths)
  • Impedance: antenna systems are typically ~50 ohm; an open will show infinite resistance on center conductor
  • Signal level: radio head unit should show measurable RF level on the front antenna input when tuned to a strong station (varies by scanner/head unit)

Diagnostic algorithm

  1. Verify the code and reproduce the symptom with the radio on. Note whether the antenna is passive, powered, or motorized.
  2. Inspect antenna mast and base for physical damage, water intrusion, or corrosion. Repair or replace as required.
  3. Remove and inspect antenna base connector for corrosion, bent pins, or loose connections. Clean and reseal if necessary.
  4. At the head unit, disconnect antenna lead and inspect connector and pin condition. Check continuity from head unit antenna input to antenna base (center conductor and shield).
  5. If continuity is open, trace the harness for damage; repair or replace sections with open conductors.
  6. If power is required at the antenna (amplifier or motorized), with ignition/radio on, measure the supply voltage at the antenna power lead. Repair supply or ground faults and check related fuses/relays.
  7. If wiring and power are good but no signal is present, test or substitute the antenna amplifier (if present) or replace the antenna assembly.
  8. After repair, clear codes, verify radio operation and perform road test/long tune check to confirm resolution.
  9. Safety note: disconnect battery or follow manufacturer's procedures before performing repairs that expose wiring or electronic modules.

Likely causes

  • Physical damage to antenna mast (bent/broken) or missing mast
  • Connector corrosion at base of antenna or at the head unit
  • Wire chafing or disconnection in harness (open circuit) between head unit and antenna
  • Failed antenna amplifier module or loss of supply voltage to amplifier
  • Connector pin pushed out or poor crimp at harness connector

Fault status

⚠️ Status
Front (outdoor) antenna circuit open — antenna continuity or feed voltage not detected by radio/body control module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B240B B241A B2420 B2440 B2A0F
406

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