C1264 — Lamp Warning Relay Circuit Short To Battery

Will C1264 clear itself?

Sometimes C1264 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What are the symptoms of C1264?

Drivers most often notice: Check Engine Light on, possible limp mode depending on the affected component, the affected system operates intermittently or not at all, increased fuel consumption in some cases.

Is it safe to drive with C1264?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

What does OBD2 code C1264 mean?

Lamp Warning Relay Circuit Short To Battery (C1264): a chassis (brakes/steering/suspension) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by faulty sensor or actuator of the affected circuit, control module driver fault, open or shorted wiring in the circuit.

How do I diagnose C1264 myself?

Start with a scan: confirm C1264, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the sensor and actuator circuits, and verify the suspect component against live data before buying parts.

When the powertrain or ABS control module detects a short to battery voltage in the lamp warning relay circuit, it logs trouble code C1264. This fault falls within the chassis category of OBD2 diagnostics, which covers safety-critical systems like antilock brakes, steering components, and suspension sensors. A short-to-battery condition means an electrical path exists where there should not be one—power from the battery is feeding into a circuit that is supposed to switch on and off under module control.

The affected module constantly watches voltage levels at the lamp warning relay driver. When that driver sees battery voltage on a circuit it expects to control (or vice versa), it registers the fault. C1264 will not set on the very first glitch—the module requires the abnormal reading to persist across a defined number of drive cycles before confirming a genuine failure. Once confirmed, the module saves freeze frame data alongside the code, capturing engine speed, load, coolant temperature, and vehicle speed at the exact moment the problem occurred.

If you are seeing C1264 on a scan tool, the vehicle is telling you something specific: the relay driver that controls one of the warning lamps has lost its ability to switch properly. Whether that is due to damaged wiring, a faulty relay, or an internal module problem depends on further testing.

Symptoms of C1264

• The Check Engine, ABS, or brake warning light stays illuminated on the instrument cluster
• The system controlling the affected lamp may operate erratically or stop working entirely
• Limp-home mode can activate, limiting engine output or shifting characteristics on some models
• Fuel economy may suffer if the module derates engine performance to protect downstream components
• Intermittent operation is common early in a wiring or connector failure—the fault comes and goes before becoming constant

Causes of C1264

• Frayed or melted wiring that shorts to a constant 12V source somewhere in the harness
• A failed lamp warning relay or the specific bulb circuit it controls
• Connectors that have water intrusion, bent pins, or pushed-out terminals causing high resistance
• Corrosion on wiring harness grounds that forces current through unintended paths
• An internal driver failure inside the ABS or body control module itself
• Aftermarket electrical accessories incorrectly tapped into the warning lamp circuit

How to Diagnose C1264

1. Connect a quality OBD2 scanner, record all stored codes, and save the freeze frame data. Note the driving conditions captured when C1264 first appeared—this guides what to reproduce during the road test.
2. Search for TSBs (technical service bulletins) for your specific make, model, and model year. Many chassis-related codes like C1264 have documented factory remedies or calibration updates that eliminate false trips.
3. Perform a thorough visual inspection of the wiring between the module and the lamp circuit. Look for melted wire insulation near hot exhaust components, chafing where harnesses rub against frame rails, and any signs of rodent damage.
4. At the relay or bulb socket connector, measure for unexpected voltage on control wires. A circuit that should show 0V when the lamp is off but instead shows 12V indicates a short-to-battery condition.
5. Check ground integrity at all related modules and the relay. Use a multimeter to verify less than 0.5 ohms resistance between ground pins and the chassis. Poor grounds cause modules to misinterpret voltage signals.
6. Clear C1264, operate the vehicle under the conditions stored in the freeze frame, and verify the code does not return. If it recurs immediately, the fault is present every drive cycle and points to a hard short rather than an intermittent connection.

Repair Options and Costs

Replace the faulty sensor or actuator (lamp relay or bulb circuit): $150–$500 for parts and labor

Repair wiring or connectors: $80–$250 depending on whether the fix involves terminal replacement, harness splice, or full connector renewal

Control module repair or replacement: $300–$1,000 when internal driver failure is confirmed and the module must be sent for rebuild or replaced outright

Total Cost to Fix C1264

Expect to spend anywhere from $80 to $1,000 depending on the root cause. Wiring repairs fall on the low end of the range and are the most frequently needed fix. Control module replacement is the most expensive scenario but is rarely the culprit—diagnose thoroughly before committing to a module swap. A professional shop will typically charge one to two hours of labor for a complete diagnosis on C1264 before any parts are ordered.

Can You Drive with C1264?

The severity rating for C1264 is short—the vehicle usually remains drivable. You may notice reduced performance, an illuminated warning light, or certain auxiliary systems being disabled. However, if the code is accompanied by stalling, failure to start, or active brake or steering warnings, do not continue driving. Have the vehicle transported to a shop for immediate diagnosis.