Code
B16A4
MITSUBISHI
B — Body
Turn signal(RH) bulb outage
Views:
UK: 5
EN: 12
RU: 3
AI status
Completed
Completed
100%
Causes
- Burned out / open filament in RH turn signal bulb
- Corroded or loose bulb socket or connector
- Broken, chafed or disconnected wiring between lamp and body control module (BCM)
- Open ground or poor ground connection at lamp
- Blown fuse or poor fuse contact in lighting circuit
- Failed turn signal relay / flasher (on older vehicles) or BCM driver fault
Symptoms
- Right-hand turn signal lamp does not illuminate when signalling
- Hazard lamps may show one side not illuminated
- Instrument cluster turn-signal indicator may flash unusually or show a lamp-out warning
- No audible or abnormal flashing rate (rapid flash if other bulbs in circuit out)
- Stored lamp-out fault code in BCM
What to check
- Visual inspection of RH turn signal bulb for broken filament or blackening
- Inspect bulb socket and connector for corrosion, bent pins or melting
- Check fuse(s) related to turn signals and associated fuse holder contact
- Operate turn signal and verify voltage at lamp socket with a multimeter
- Check continuity between lamp connector and BCM connector and measure ground
- Swap bulb with known good lamp (or swap left/right) to confirm bulb vs circuit
Signal parameters
- Nominal supply voltage at lamp connector: ~12 V when turn signal ON (11–14 V acceptable)
- Expected bulb resistance (typical 21 W lamp): ~6–8 ohms (cold)
- Lamp current for 21 W bulb: ~1.6–2.0 A
- Open-circuit reading: infinite resistance between supply pin and bulb filament
- Ground continuity: near 0 ohms from socket ground to chassis ground
- Flasher/BCM output: pulsed 0–12 V at turn signal flash frequency ~1–2 Hz
Diagnostic algorithm
- Record the fault code and any freeze-frame data; note whether code is current or intermittent.
- Visually inspect RH turn signal bulb; remove and inspect filament. Replace with a known good bulb and re-check.
- With a good bulb installed, operate the RH turn signal and verify ~12 V at the supply terminal of the socket and good ground at the ground terminal.
- If no voltage, check associated fuse(s) and fuse holder continuity; replace if blown or poor contact.
- If fuse OK but no voltage, trace supply circuit back to BCM/relay: check continuity between bulb connector and BCM connector and inspect wiring for damage, chafing or corrosion.
- Check ground continuity from socket ground to chassis and clean/repair ground if high resistance.
- Wiggle test connectors and wiring while signalling to detect intermittent faults.
- If supply and ground are good at the socket but bulb still not detected as OK by BCM, inspect BCM outputs and wiring for high resistance; if wiring is good, consider BCM driver fault and consult manufacturer procedures before replacing module.
- After repairs, clear codes with a scan tool and verify system operation over several cycles; road-test and re-scan to confirm repair.
Likely causes
- Defective RH turn signal bulb (most common)
- Corrosion or poor contact at bulb socket/connector
- Open or damaged wiring harness to RH lamp
- Faulty ground at lamp assembly
- Blown fuse or poor fuse holder contact
- Faulty BCM output (least common)
Fault status
Status
Turn signal (RH) bulb outage detected — open/high resistance in right turn lamp circuit. Check bulb, socket, wiring and BCM output.
Repair difficulty: Easy
Diagnostic time: 0.2-0.8 hours
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