Hi all

 

I am working on a autohold solution for my 16' vRS.

I need to find either:

A) 12v that becomes live once the car is moving, normally 0v

12v that becomes live when the vehicle is stationary which is 0v when the car is moving

 

So far I've tried the adaption list for the light channels hoping I could use that as a trigger - I thought a few looked promising but I have test them and they don't work

1) Klemme 15 mit Nachlauf bis Fahrzeugstillstand (Terminal 15 with follow-up vehicle standstill)

2) Klemme 15 ohne nachlauf (Terminal 15 without running / trailing)

 

Ive actually tried all of them and its no good - you can have have an on/off with stop start, and handbrake on/off but not vehicle moving.

I'm looking for any other ideas of a simple trigger for when the vehicle is 1mph>, without writing code and having a decoder to extract the data from the EOBD data protocol

 

Thanks

Front parking sensors? Do they deactivate when stationary? Or are they permanently on?

Good thought - I don't have the front sensors so I can't test it though :-(

On 2017-05-13 at 22:21, pist0nbr0ke said:

Front parking sensors? Do they deactivate when stationary? Or are they permanently on?

Same as rear unfortunately, turns on with the "P<-Button" or when selecting reverse and turns off at about 20 Kph.

I'm not sure if anything in the car will have that, most things should be CAN-bus connected so will able to use the speed signal.

 

The only off the shelf option seems to be a taxi CAN-bus speed decoder. It'll give a pulsed output dependant on speed that you can probably interface to.

 

Alternatively, you could use an Arduino or similar to listen to the CAN-bus and give you a 12v signal based on speed/movement.

Thanks for the input

 I have contacted a company who supply the taxi canbus speed decoder and asked if the  pulse (currently around 1hz per mph) can be set to permanently.

 

ive also thought of using a capacitor and transistor to smooth the pulse into a constant feed

Where do the VW and Audi models get their signal from, as they have a "hold" system that uses the electric handbrake with the DSG

 

John

4 hours ago, jjc said:

Where do the VW and Audi models get their signal from, as they have a "hold" system that uses the electric handbrake with the DSG

 

John

The VW system doesnt use the electric handbrake (EPB) for autohold, it uses the ABS unit to maintain brake line pressure. It only activates the EPB after a pre-determined time (something like 5-7 mins) if you haven't moved.

 

The speed signal comes directly from the ABS sensors to the ABS ECU, from there it is shared on the Powertrain BUS and to the other slower speed BUS's as required so everything can use the data

How about one of these rigged up to lean on a tyre?

 

There are canbus to 12v signal converters used primarily for wiring up aftermarket stereos that require 12v signals for lights, ignition etc.

 

I know you can get them with a switched 12v signal when moving as it disables the video screen if playing a DVD.  A Google search should see you right.

Interesting - I'll have a look thanks