Code
B16A3
MITSUBISHI
B — Body
Turn signal(LH) circuit short
Views:
UK: 5
EN: 13
RU: 3
AI status
Completed
Completed
100%
Causes
- Short to ground in LH turn signal wiring
- Short to battery/ignition power in LH turn signal wiring
- Damaged or pinched wiring harness near lamp, connector, or chassis grounding point
- Corroded or melted bulb socket or connector
- Faulty or incorrect replacement bulb (LED vs incandescent) causing abnormal current/feedback
- Faulty BCM/body control module or internal driver transistor
Symptoms
- Left turn signal (exterior lamp) not illuminating or intermittent operation
- Rapid flash (hyperflash) or no flash on LH side
- Turn signal fuse blows when signal selected or when hazards used
- Warning/chime or dashboard indicator may show error or irregular behavior
- Related lighting circuits may behave abnormally if shared wiring is affected
What to check
- Scan vehicle and read/confirm B16A3 and any related codes; record freeze frame/live data
- Visually inspect LH turn lamp, bulb type, socket, and harness for damage, corrosion, or water
- Check related fuses and relays for damage and correct rating
- With ignition ON, measure voltage at LH lamp connector with turn signal activated (use meter; observe proper safety procedures)
- With circuit de-energized, check continuity and resistance between turn positive and ground to detect shorts
- Wiggle test harnesses and connectors while monitoring lamp operation or multimeter for intermittent faults
Signal parameters
- Voltage at LH turn lamp positive terminal when switch ON: approx. battery voltage (~11–14 V)
- Voltage at LH turn lamp positive terminal when switch OFF: 0 V (no intentional feed) — significant voltage suggests short to power
- Typical current draw (incandescent bulb): roughly 0.5–3 A depending on bulb. LED modules are lower but vary by design
- Resistance between turn positive and chassis ground with circuit de-energized: high/open (>>10 kΩ). Low resistance (
- Blink/pulse rate: ~60–120 cycles/min for normal system; large deviations may indicate load or driver issues
Diagnostic algorithm
- Retrieve and record codes; clear code and re-run lamp function to see if B16A3 returns.
- Inspect LH lamp assembly: remove bulb, inspect socket, clean corrosion, check for water ingress and correct bulb type.
- Operate turn signal with bulb removed; if fuse blows or code returns, suspect wiring/short upstream (do not leave unprotected circuits powered repeatedly).
- With ignition ON and turn signal ON, measure voltage at the lamp positive pin. If voltage present with switch OFF, suspect short to power. If no voltage with switch ON, suspect open circuit.
- With power off, measure resistance between lamp positive and chassis ground. Low resistance suggests short to ground—trace harness for chafing or damaged insulation.
- Isolate sections by disconnecting connectors along the harness and re-check resistance/voltage to localize the short location.
- If wiring and lamp assembly check OK, inspect BCM connector pins and grounds. If BCM driver appears defective after wiring verified, consider BCM replacement or module bench test per service procedures.
- Repair or replace damaged wiring, socket, bulb, or connector. Secure and protect harness from future chafe or water intrusion.
- After repair, clear codes, re-test turn function and confirm no recurrence of B16A3.
Likely causes
- Corroded/melted socket or connector at LH lamp allowing short
- Wire chafed and contacting chassis (short to ground) near rear/front lamp or underbody
- Aftermarket lamp or LED retrofit creating low resistance feedback into BCM
- Water intrusion in lamp assembly causing intermittent short
- Harness pin pushed out or bent in multi-pin connector causing cross-contact
Fault status
Status
Turn signal (LH) circuit short — low resistance or short detected in left-hand turn signal wiring or lamp circuit. Inspect lamp, harness, connectors, fuses and BCM.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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