What Does B1505 Mean?
This code indicates the Body Control Module (BCM) has detected an abnormal voltage condition in the right turn signal lamp circuit, where the circuit is experiencing a short to battery voltage (constant 12V+ power). This means the right turn signal circuit has unintended contact with a power source, preventing proper operation of the turn signal lamp. The BCM monitors lamp circuits for proper resistance and voltage patterns, and sets this code when it detects voltage on the output side when the circuit should be off.
Common Causes
45%
Damaged or chafed wiring harness causing direct contact between the turn signal circuit wire and a 12V+ power wire, typically in areas where harnesses flex or pass through body panels
30%
Faulty right turn signal lamp socket with internal short to power, corrosion causing cross-circuit contact, or incorrect bulb installation causing terminal bridging
15%
Failed Body Control Module (BCM) with internal component failure causing false short detection or actual shorted output driver
10%
Aftermarket wiring modifications, trailer wiring harness, or lighting accessories incorrectly tied into turn signal circuit providing backfeed voltage
Diagnostic Steps
1
Step 1: Perform visual inspection of right turn signal lamp socket and bulb - remove bulb, inspect socket terminals for corrosion, melting, or bent contacts that may be touching power pins. Check for correct bulb type and proper installation
2
Step 2: Disconnect right turn signal lamp connector at the lamp socket. Using a digital multimeter, measure voltage at the turn signal feed wire (BCM side) with ignition on and turn signal off - should read 0V. If voltage is present with lamp disconnected, proceed to Step 3
3
Step 3: Disconnect BCM connector(s) controlling turn signals. Trace and inspect the turn signal circuit wiring from BCM to lamp, checking for wiring damage, pinch points at door hinges, trunk hinges, or body pass-throughs. Use multimeter in continuity mode to test for short to battery voltage (check resistance between turn signal wire and known 12V+ circuits)
4
Step 4: If no wiring damage found and voltage still present at BCM connector terminal with BCM disconnected, check for aftermarket wiring, trailer harnesses, or lighting modifications that may be backfeeding voltage into the circuit. Disconnect any non-OEM components
5
Step 5: If all wiring checks pass and no shorts found externally, reconnect all components except BCM. Measure resistance from BCM turn signal output pin to ground - should read open circuit (OL) or very high resistance. Low resistance indicates wiring short; normal resistance suggests BCM internal fault
6
Step 6: After repairs, reconnect all components, clear codes, and perform functional test of right turn signal operation. Monitor live data for turn signal circuit voltage and current draw to confirm proper operation and verify code does not return
Estimated Repair Cost
$75 - $600
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an abnormal voltage condition in the right turn signal lamp circuit, where the circuit is experiencing a short to battery voltage (constant 12V+ power). This means the right turn signal circuit has unintended contact with a power source,...
The most common cause of B1505 (Lamp Turn Signal Right Circuit Short To Battery) is: Damaged or chafed wiring harness causing direct contact between the turn signal circuit wire and a 12V+ power wire, typically in areas where harnesses flex or pass through body panels
Typical repair costs for B1505 range from $75 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is drivable but right turn signal may not function properly, creating a significant safety hazard as other drivers cannot see your turn intentions. Repair should be completed promptly to maintain legal compliance and prevent accidents, especially before nighttime driving or highway use.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1505 to identify the root cause.
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Quick Info
Category
Body
System
Exterior Lighting System
Difficulty
Type
Manufacturer
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