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.
Circuit Description
Wheel speed sensors on each wheel deliver an input signal to brake Electronic Control Unit (ECU) for the Anti-Lock Brake System (ABS). Brake ECU converts input signals from wheel speed sensors to a 4-pulse input signal to the instrument cluster. Instrument cluster then converts 4-pulse input signal to a rectangular waveform and then sends vehicle speed signal to Engine Control Module (ECM). DTC is set if there is no vehicle speed signal to ECM while vehicle is being driven. Brake ECU may also be referred to as ABS ECU. Possible causes are:
- Vehicle speed circuit is open or shorted between instrument cluster and ECM.
- Defective instrument cluster.
- Defective brake ECU.
- Defective ECM.
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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.