29 September 2021

Moar Teh Stoopid

I've done a deep dive of the function of the brake pedal position sensor.

It is a potentiometer.

What it does is drop the 5v signal voltage to alert the body control module (BCM) that the brake pedal has been depressed.

I haven't done the math to determine what the actual voltages are...

There will be two voltages less than 5v it's looking for.  The lower value is for the pedal at rest and the higher with it depressed.

Literally using a pot as a switch to send a binary signal.

The brake light logic is IF voltage > X volts THEN pedal is depressed.

When the pedal is shown as depressed it turns on the brake lights and lets other brake related things happen, like ABS.

The BCM determines how MUCH the pedal has moved by measuring the pressure of the brake fluid.

Grumble.

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