B1502

Code

Other B — Body

Lamp Turn Signal Left Circuit Short To Ground

Brand: Other

Type: B — Body

Views: UK: 30 EN: 57 RU: 44

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring contacting chassis ground
Corroded or water-damaged lamp connector or socket
Faulty or shorted turn signal bulb (incandescent) or LED assembly
Aftermarket LED conversion without proper load/resistor
Faulty BCM or lamp driver module
Shorted splice or connector in harness

Symptoms

Left turn signal inoperative (no flash)
Fuse for turn signal circuit blown or repeated fuse failure
Hyper-flash or erratic flash rate (on some systems)
Other lighting functions on same circuit may be affected
Warning lamp or message for exterior lamp fault on dash

What to check

Scan BCM/body module for active and stored codes and freeze-frame data
Visual inspection of left turn lamp, socket, and connector for corrosion or water
Remove lamp/bulb and inspect filament/LED and socket contacts
Check fuse(s) related to turn signals and replace if blown; observe if fuse blows again
Back-probe the left turn signal output with turn signal commanded and measure voltage
Measure resistance between lamp output pin and chassis ground with harness disconnected

Signal parameters

Normal: pulsed output ~12 V (when lamp commanded ON). Frequency depends on system (1–4 Hz for traditional flasher; higher for BCM/PWM drivers).
Short-to-ground symptom: output pin voltage near 0 V when commanded and much lower than expected
Typical incandescent bulb load: a few ohms to tens of ohms (varies by bulb). LED assemblies present much higher resistance/impedance.
Measured continuity: an unexpected near-zero ohms from output circuit to chassis ground with lamp/harness disconnected indicates a short

Diagnostic algorithm

Read and record all related codes from BCM and other modules. Note whether the code is current or historical.
Verify the customer's complaint and observe symptom. Operate left turn signal while monitoring fuse and instrument indications.
Inspect visible wiring, harness routing and lamp assembly for damage, corrosion, water entry or loose connectors.
Remove the left turn lamp/bulb. Inspect bulb/LED module and socket for corrosion or shorted filaments/contacts. Replace with known-good bulb if uncertain.
With lamp removed, command the left turn signal ON and back-probe the lamp output at the connector. Expect a pulsed ~12 V. If voltage is near 0 V, a short to ground is likely downstream.
Disconnect the harness at the BCM/driver module if accessible. Measure resistance from the output pin to chassis ground. Low resistance indicates a short in the harness or downstream circuit.
If short is present in harness, perform a localized continuity test and inspect wiring sections (use a fused jumper or test light to locate short). Repair damaged wiring, replace corroded connectors, and seal to prevent moisture intrusion.
If no short is found in wiring, suspect the BCM or lamp driver. Verify other outputs from the same module, consult wiring diagrams, and consider module bench testing or replacement per manufacturer procedure.
After repair, clear codes and retest system to confirm the fault does not return.
Safety note: isolate battery power or remove fuses as needed when performing harness repairs to prevent shorts and protect equipment.

Likely causes

Wire insulation abrasion at a harness routing point causing contact with ground
Moisture in lamp socket causing low-resistance path to ground
Defective bulb or LED module internally shorted
Incorrect component (wrong bulb type) or missing resistor on LED retrofit

Fault status

⚠️ Status

Left turn signal circuit short to ground detected. Lamp may not operate; inspect wiring, socket and bulb for short. Check BCM output if harness is intact.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours