C1264 — Lamp Warning Relay Circuit Short To Battery #

The code description may vary depending on the vehicle manufacturer.

• Lamp Warning Relay Circuit Short To Battery (generic, most OEMs)
• Brake Warning Lamp Relay Circuit Short to Battery (Toyota, Lexus)
• Stop Lamp Relay Input Circuit High (Nissan, Infiniti)

Summary of DTC C1264 #

The C1264 trouble code indicates a problem in the lamp warning relay circuit, specifically a short to battery voltage. In practical terms, a “short to battery” means that the circuit has unintended contact with positive voltage, which can cause false signals or improper function of the warning lamp system. The lamp warning relay, managed by the vehicle’s electronic control unit (ECU), is responsible for activating warning lights—most often related to the brake system. When C1264 is stored, it signals that the relay circuit is continuously receiving voltage when it should not, potentially leading to false warning lights or, in rare cases, failure to alert you to a genuine fault. This code is found in many modern vehicles using advanced brake or stability control systems.

Frequent Symptoms for Code C1264 #

When the C1264 code is active, you might notice certain telltale signs as you drive. Often, the most obvious symptom is a dashboard warning light that stays on or behaves erratically. Sometimes, you may detect additional electrical issues, depending on the vehicle design and the severity of the fault. Even in the absence of visible symptoms, the code should not be ignored, as it can mask more critical warning signals.

• Brake warning light remains illuminated
• Intermittent or flickering brake/ABS warning indicator
• Other dashboard warning lights may also activate
• No obvious driveability issues in most cases
• Unusual clicking from relay under the dash (rare)

Probable Causes for C1264 (Most to Least Common) #

The root causes of C1264 typically relate to the electrical pathways between the lamp warning relay and the vehicle’s power supply. Diagnosing the issue involves considering both straightforward electrical faults and more complex, component-level failures.

1. Short circuit to battery voltage in the relay wiring harness
2. Failed or stuck lamp warning relay
3. Corroded or damaged connectors at the relay or control module
4. Incorrect or aftermarket wiring modifications
5. Faulty Electronic Control Unit (ECU, also called ABS or BCM module)

Step-by-Step Diagnostic for C1264 #

Resolving C1264 requires a structured approach, starting from the simplest checks and progressing to more involved inspections. Here’s how a professional would typically approach it:

• 1. Scan for codes: Confirm presence of C1264 and look for related codes (ABS, BCM, or brake system).
• 2. Inspect warning lamp operation: Check if the warning lamp illuminates with ignition ON and goes out as expected.
• 3. Visual inspection: Examine the lamp warning relay, wiring harness, and connectors for signs of damage, corrosion, or aftermarket modifications.
• 4. Check relay function: Test the relay for proper operation using a multimeter or by swapping with a known good relay.
• 5. Measure voltage: With the relay disconnected, measure for voltage at the relay input and output terminals; check for unexpected voltage (should be near 0V with ignition OFF).
• 6. Inspect ECU/Module: If all other steps check out, consult the wiring diagram and test for shorts to battery within the ECU or control module itself.
• 7. Clear codes and retest: After repair, clear codes and verify the system operates normally.

Possible Repairs for C1264 #

Once you identify the root cause, repairing code C1264 is usually straightforward. Prioritize the most likely and cost-effective fixes before considering module replacement.

• Repair or replace damaged wiring in the lamp relay circuit
• Replace a faulty lamp warning relay
• Clean or repair corroded connectors at relay and module
• Remove or correct any aftermarket wiring modifications
• Replace the ECU or control module (only if all other causes are eliminated)

Is It Safe to Drive with Code C1264? #

Generally, yes—but with limitations. C1264 typically does not affect core braking performance, but it can interfere with your ability to receive genuine warning signals. If the warning lamp is stuck ON, you might miss a new, real fault. If you notice new symptoms (such as braking issues, multiple warning lights, or unusual noises), avoid driving and seek professional help immediately. For routine driving, address this code promptly to ensure all safety systems are fully functional.

Vehicles Most Commonly Affected by C1264 #

Based on repair industry data and OEM documentation, C1264 is most frequently reported in the following vehicles, especially those equipped with advanced brake or stability control systems:

• Toyota Camry, Corolla, RAV4 (2005–2015)
• Lexus RX, ES, IS (2007–2014)
• Nissan Altima, Sentra, Maxima (2003–2012)
• Infiniti G35, FX35 (2005–2010)
• Some Ford and Mazda models with similar relay systems

Common Mistakes & Best Practices with C1264 #

Misdiagnosis of C1264 often stems from overlooking simple wiring faults or assuming a module is at fault without adequate testing. Always follow a methodical approach to prevent unnecessary repairs or part replacements.

• Replacing the ECU or control module before confirming wiring and relay integrity
• Ignoring basic visual inspection for corrosion or loose connectors
• Failing to check for aftermarket alarm or remote start systems that may interfere with relay circuits
• Not clearing codes and retesting after repair

Express FAQ for C1264 #

Here are quick answers to questions drivers and technicians frequently ask about C1264:

• Q: Will my brakes stop working with code C1264?
  A: In most cases, the brakes will still function, but you may not get accurate warnings if another issue occurs.
• Q: Can I fix C1264 myself?
  A: If you’re comfortable checking fuses, relays, and visible wiring, you can address simple causes. For deeper diagnostics, especially module testing, seek a professional.