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.
Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter [08/2019 - ]: Description
This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the radio and display receiver assembly.
The Automatic Sound Levelizer (ASL) function automatically adjusts the audio system volume in order to compensate for increased vehicle noise (vehicle noise tends to increase as vehicle speed increases). The ASL adjusts the volume based on vehicle speed signals sent from the meter circuit plate.
HINT:
- A voltage of 12 V or 5 V is output from each ECU and then input to the meter circuit plate. The signal is changed to a pulse signal at the transistor in the meter circuit plate. Each ECU controls its respective system based on this pulse signal.
- If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the following diagram will not operate normally.
NO RELATED
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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.