B1485: Brake Pedal Signal Short to Battery
The B1485 code indicates that the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected a short circuit to battery voltage (B+) on the brake pedal input signal circuit. This circuit normally carries a low voltage or ground signal when the pedal is pressed; the presence of constant or intermittent battery voltage on this wire points to chafed harness insulation contacting a B+ wire, an internal short in the brake pedal switch (stop lamp switch), a damaged connector with bent or corroded pins bridging signal and power terminals, or (rarely) an internal BCM/PCM failure at the brake pedal input pin.
1. Commonly Affected Makes
2. Most Common Causes
- Brake pedal signal circuit wire chafed or cut against a B+ power wire
- Brake pedal switch (stop lamp switch) internally shorted to battery voltage
- Brake pedal switch connector damaged, with bent pins or corrosion bridging signal and power terminals
- Internal BCM/PCM failure at the brake pedal input pin (rare)
3. Symptoms You Will Notice
- Brake lights staying on continuously or not working properly
- Cruise control disengaging or not engaging
- Transmission shift interlock malfunction (cannot shift out of Park)
- Check Engine Light or Brake Warning Light illuminated
4. Step-by-Step Diagnosis
Verify the code and check for related brake system codes.
Inspect the brake pedal switch and connector for damage, corrosion, or bent pins.
Test the brake pedal signal circuit for voltage with the pedal released (should be low/ground); if battery voltage is present, isolate the short.
Check for chafed or pinched wiring in the harness, especially near the pedal assembly or along the firewall.
If wiring and switch are okay, test the BCM/PCM input pin for internal short (rare).
5. Frequently Asked Questions
Is it safe to drive?▼
No, this is a high-severity issue. A short to battery on the brake signal can cause brake lights to malfunction, confuse the transmission shift interlock, and disable cruise control. It may also affect brake system operation. Have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. A brake pedal switch replacement is usually $50–$150, while wiring repair can be $100–$300. BCM replacement (rare) could exceed $500.