Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter: Description

WARNING: This page is about a different car, the 2008 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.

This circuit is necessary for the ASL (Auto Sound Leveliser) built into the radio receiver.

Speed signals are received from the combination meter and used for the ASL.

The ASL function automatically adjusts the sound data in order to enable the driver to hear clear audio sound even when vehicle noise increases (as vehicle noise increases, the volume is turned up, etc.).

HINT:

A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.
If a short occurs in an ECU, all systems in the diagram below will not operate normally.