Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC C1294: BRAKELIGHT Switch Circuit Always Active
2000 Buick Century CustomSECTION DTC C1294: BRAKELIGHT Switch Circuit Always Active
- Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK under DIAGNOSIS & TESTING. After performing diagnostic system check, go to next step.
- Observe brakelights. If brakelights are on without pressure applied to brake pedal, go to next step. If brakelights are not on, go to step 4 .
- Disconnect stoplight switch connector. Check brakelights. If brakelights are still on, go to step 5 . If brakelights are not on, go to step 6 .
- Disconnect EBCM harness connector. Install Universal Pinout Box (J 39700) using Cable Adapter (J 39700) to EBCM harness connector only. Check voltage between stoplight switch input circuit at pinout box and a known-good ground. If any voltage is present on stoplight switch input circuit without pressure applied to brake pedal, go to next step. If no voltage is present, go to step 7 .
- Repair short to voltage in stoplight switch input circuit. After repairs, go to step 9 .
- Adjust or replace stoplight switch. After repairs, go to step 9 .
- Reconnect all connectors. Install scan tool. Using scan tool, select ABS Data Display. Carefully drive vehicle for 2 drive cycles while monitoring brake input data on scan tool (a drive cycle consists of starting engine, driving at speed greater than 25 MPH and back to zero MPH, and then turning ignition off). If DTC C1294 resets in the last 2 drive cycles, go to next step. If DTC C1294 does not reset, system is okay.
- Replace EBCM. After replacing EBCM, go to next step.
- Using scan tool, clear DTCs. Drive vehicle at speed greater than 25 MPH, then recheck DTCs. If DTC resets, go to step 2 . If DTC does not reset, system is okay.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.