B1504 – Lamp Turn Signal Right Circuit Open: Symptoms, Causes, Diagnosis & Repair Cost (2026 Guide)

B1504

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Overview

The control module stored B1504 because it detected a problem with: Lamp Turn Signal Right Circuit Open.

B1504 relates to Lamp Turn Signal Right Circuit Open. Use a quality scan tool, follow wiring diagrams for your vehicle, and confirm tests before replacing expensive parts.

What does the B1504 code mean?

When B1504 is set, the vehicle’s diagnostics detected an issue described as: Lamp Turn Signal Right Circuit Open. In practice, the ECM/PCM (and related modules) compare sensor inputs, commanded outputs, and self-tests for that subsystem. The exact repair depends on whether the fault is wiring-related, component-related, or a rationality/performance issue for this circuit or system.

Common symptoms of B1504

  • Intermittent warning chime
  • Passenger sensor messages
  • SRS/airbag warning lamp
  • Seat belt warning issues
  • Safety system disabled message
  • Scan tool shows restraint codes

Possible causes

  • Fault affecting Lamp Turn Signal Right Circuit Open (wiring, connector, or component)
  • Electrical fault in the monitored circuit
  • Control module strategy or calibration issue
  • Component failure in the described system
  • Control module or software calibration issue (less common—verify tests first)
  • Past repairs or aftermarket parts causing out-of-spec operation

How to diagnose B1504

  1. Scan for B1504 and review freeze frame / pending codes for related faults
  2. Inspect connectors and wiring related to: Lamp Turn Signal Right Circuit Open
  3. Compare live data and commanded vs actual values for the affected system (per service information)
  4. Perform circuit tests appropriate to the fault type (continuity, voltage, resistance) before replacing parts
  5. Confirm power and ground integrity at the relevant module or sensor
  6. After repair, clear DTCs and verify under the conditions that originally set B1504

Tip: Use a scan tool that shows live data and freeze frame for the conditions when the code set.

Severity of code B1504

High: This fault can impact safety-related systems or core drivability—prioritize professional diagnosis.

Can you drive with B1504?

Short trips may be okay if the vehicle feels normal, but have it diagnosed—especially if performance, safety warnings, or overheating are present.

Avoid heavy acceleration, towing, or long highway drives until the cause of B1504 is confirmed and repaired.

How to fix it (step-by-step)

  1. Start with visual inspection and connector cleaning/tightening where needed
  2. Confirm failure mode with testing—avoid swapping parts without evidence
  3. Repair wiring or replace the failed component per manufacturer procedure
  4. Clear faults, run relearns if required, and road test to confirm

Repair & fix options

  • Clear codes and verify with drive cycle
  • Test component against service limits
  • Inspect connectors and wiring first
  • Clear codes and verify repair with a drive cycle and readiness where applicable
  • Reinspect related monitors if the code returns after repair

Typical repair cost

$120 – $1,800+ for many common repairs

Estimated cost breakdown for B1504
Repair type Typical range
Diagnostic And Minor $120 – $600
Common Component Work $200 – $900
Major Subsystem Repair $400 – $1,800+
Severe Or Replacement Varies widely—see a qualified shop

How to help prevent B1504 in the future

  • Fix new codes early before secondary damage or catalyst stress
  • Keep connectors clean and secure; address rodent or water intrusion in harnesses
  • Use the correct fluids/parts for your vehicle and service intervals
  • Avoid ignoring pending codes after battery work or repairs

When to see a mechanic

Schedule diagnosis if the check engine light is on, drivability is worse, or you notice new noises, smells, or warning lamps. For safety-related (SRS/ABS) or overheating symptoms, prioritize a qualified shop immediately.

Common mistakes when diagnosing B1504

  • Replacing sensors/modules without verifying wiring and reference voltages
  • Ignoring related codes that identify the real root cause
  • Clearing codes without a verification drive cycle

Common vehicles & notes for B1504

  • Ford / Chevrolet models (common examples—verify for your vehicle)
  • Toyota / Honda applications vary by engine and model year
  • Many other makes—this is a standardized OBD-II definition: Lamp Turn Signal Right Circuit Open

B1504 is reported across many platforms including Ford, Chevrolet, Toyota, Honda. Always use VIN-specific service information for testing limits and calibration steps.

Frequently asked questions

What does B1504 mean?

B1504 indicates a fault involving Lamp Turn Signal Right Circuit Open, based on what the control module detected during self-tests or live monitoring.

Is it safe to drive with B1504?

If the vehicle runs normally and no warning lights are flashing, short trips may be reasonable—but avoid ignoring symptoms like misfire, overheating, ABS/SRS warnings, or major loss of power.

How much does it cost to fix B1504?

Typical repairs often fall in the ranges shown on this page, but final cost depends on labor rate, parts quality, and whether the issue is wiring vs. a major component.

What is the most common cause of B1504?

Most shops start with wiring/connectors and the directly monitored component for “Lamp Turn Signal Right Circuit Open,” then expand testing if the fault returns.

Will B1504 clear itself?

It may become intermittent, but if the underlying fault remains, the code will usually return—especially after a drive cycle.

Can a weak battery cause B1504?

Low system voltage can cause odd sensor/module behavior, but you should still validate the actual DTC and perform normal circuit/component tests.

Related tools

This information is for educational purposes only and is not a substitute for hands-on diagnosis. Always follow manufacturer service information and consult a qualified automotive technician for repairs.