Code
B1502
FIAT
B — Body
Left turn indicator warning lamp short to ground
Views:
UK: 4
EN: 10
RU: 5
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring contacting chassis ground
- Corroded or damaged connector at the lamp or wiring harness
- Failed/shorted indicator lamp (incandescent filament short or LED driver fault)
- Internal short or failed driver in instrument cluster / body control module (BCM)
- Aftermarket accessory or recent repair that altered wiring and created a short
Symptoms
- Left turn signal lamp does not operate or is nonfunctional
- Turn signal may not flash or may remain on continuously when left turn selected
- Dash left-turn indicator/warning lamp illuminated or not operating correctly
- Possible blown fuse for exterior lamps
- Other electrical oddities on left-side lighting circuits
What to check
- Read and record freeze-frame / live data with a scan tool; confirm B1502 presence and any related codes
- Visually inspect left turn lamp, socket, connector and wiring harness for damage, corrosion, pin pushed out or water ingress
- Check related fuses and relays for open or blown condition
- Unplug the left turn lamp connector and see if the fault clears in the scanner
- Measure continuity between lamp circuit terminal and chassis ground with connector disconnected
- Measure voltage at the lamp connector while activating turn signal (expect pulsed ~12 V when healthy)
Signal parameters
- Resting voltage at lamp connector (turn signal off): near 0 V (no feed) or open-circuit
- Activated voltage: pulsed approx. 9–14 V (typical 12 V system) when turn signal is operating
- Expected bulb current (incandescent): typically 0.5–2 A per lamp depending on bulb type
- Continuity to chassis ground with connector disconnected: should be open/high resistance (no direct short)
- Resistance of good bulb (cold): typically several ohms (depends on bulb type); LED modules will measure differently and draw much lower current
Diagnostic algorithm
- Verify the code with a diagnostic scan tool; clear code and attempt to reproduce. Note whether code returns immediately or only under operation.
- Perform a visual inspection of left front/rear lamp, socket, and harness routing. Look for pinched wiring, chafe points, corrosion or melted insulation.
- Disconnect the left turn lamp connector. With ignition on, re-scan or re-test the turn signal. If the code clears, the problem is in the lamp assembly or its wiring; if it remains, suspect cluster/BCM or wiring upstream.
- With connector disconnected, check continuity between the lamp circuit pin and chassis ground. A short to ground will show near-zero ohms — trace and repair wiring to remove short.
- With turn signal activated, back-probe the lamp feed at the connector. Confirm pulsed voltage when healthy. If there is constant 0 V/ground present, trace wiring to find contact with chassis or failed driver output.
- Inspect and if necessary test/replace the bulb or LED module. Re-test after replacement.
- If wiring and lamp assembly are good but short remains, inspect connector pins at harness and at module for bent pins, corrosion or damage. Repair or replace damaged connector/pins.
- If all external wiring and lamp tests pass, test the output driver at the instrument cluster/BCM per manufacturer procedure. Replace module only after confirming internal driver failure.
- After repair, clear codes and road-test to confirm fault does not return. Verify normal turn signal operation and that no related codes remain.
Likely causes
- Wiring harness abrasion at a grounding point or under trim near wheel arch
- Corroded lamp socket causing low resistance to ground
- Lamp assembly failed (shorted filament or failed LED electronics)
- Instrument cluster or BCM output stage fault
- Loose/crimped connector pin making intermittent short
Fault status
Status
Left turn indicator warning lamp circuit: short to ground detected. Circuit continuity to chassis is lower than expected which can prevent normal lamp operation and may overload the driver or blow a fuse.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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