Speed signal to control doors auto lock

[lkos]

Hello, 

I need help to find the signal that activates after some speed (I guess around 20km/h) is reached (for example seatbelt warning or ABS). I'm

planning to make a simple schematic to simulate manual press of door power switch once the speed is reached.

Thanks

[flash22]

no such signal exists, you will need to use the VSS pulse (like a pwm) then work out the pulse for the desired speed, the lock output would also need to be a momentary pulse

this can be achieved with a car alarm or an Arduino with a simple script

[tavy]

Hi, 

I took this speed pulse from dash clock connector, fiitted a wire from this connector to radio speed signal input in order to achieve a speed senzitive volume and it works like a charm.

[lkos]

Thanks very much guys, where is this dash clock connector? In the instrument cluster (speedometer) or the clock that is above the media/navigation? Wondering what is this PWM signal used in the clock for? 

Otherwise PWM is good - just a simple LP filter and it becomes a DC voltage level for a certain speed. 

Thanks again for the fast replies. 

 

 

 

[flash22]

There is a VSS on the head unit what's easier to get at

[lkos]

Great, I would not like to disassemble the instrument panel. Thanks flash22.

 

[flash22]

The vss is a square wave (5v/div, 20ms/div on the scope) the amplitude stays the same, but the wave form narrows as speed increases

 

[lkos]

Thanks and sorry, was busy with other things. Please 2 questions:

1. Is this a frequency modulation (the whole pulse period decreases with speed increase) or pulse width modulation (half of the pulse decreases, the other increases)? 

2. Do you know the VSS (SPD?) pin number on the socket? I can't find wiring diagram. My head unit is 86140-02010

Many thanks.