12v required when car is moving - for AutoHold tweak

   #1  

Xpower

Verified VCDS User
Verified
Joined
Jun 14, 2014
Messages
61
Reaction score
25
Location
UK
VCDS Serial number
C?ID=163029
Hi all

I am close to an autohold solution for my 16' vRS without EPB, it will require a little piece of hardware.

For it to work I need to find either:
A) 12v that becomes live once the car is moving, normally 0v
B) 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 a trigger which switches on/off with stop start, and a trigger for handbrake on/off but not vehicle moving/not moving.
I'm looking for any other ideas of a simple trigger for when the vehicle is 1/2mph+, without having to write code into something like an arduino and have a bliuetooth EOBD dongle and having a decoder to extract the data from the EOBD data protocol

Thanks
 
   #2  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,925
Reaction score
33,652
Location
USA
VCDS Serial number
HC100001
Hmm, what reason would there be for a car maker to provide a 12V signal that shows when the car is in motion?

If I were trying to do this in a "current" car, I'd passively listen on the powetrain CAN. Some message being broadcast on there will have the vehicle speed.

-Uwe-
 
   #3  

Phastazphuk

Verified VCDS User
Verified
Joined
Oct 1, 2014
Messages
1
Reaction score
0
Location
UK
VCDS Serial number
C?ID=207665
Auto hold solution

Hi all

I am close to an autohold solution for my 16' vRS without EPB, it will require a little piece of hardware.

For it to work I need to find either:
A) 12v that becomes live once the car is moving, normally 0v
B) 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 a trigger which switches on/off with stop start, and a trigger for handbrake on/off but not vehicle moving/not moving.
I'm looking for any other ideas of a simple trigger for when the vehicle is 1/2mph+, without having to write code into something like an arduino and have a bliuetooth EOBD dongle and having a decoder to extract the data from the EOBD data protocol

Thanks

Have a look at the central locking.........you can set it up so the car locks at about 10 mph so you should be able to find a feed that way.........
 
   #4  

DV52

Verified VCDS User
Verified
Joined
May 16, 2014
Messages
5,469
Reaction score
5,934
Location
Melbourne, Australia
VCDS Serial number
C?ID=194404
^^^^^^^^ So why isn't the trigger for the SS function an acceptable surrogate of vehicle movement?
 
   #5  

Xpower

Verified VCDS User
Verified
Joined
Jun 14, 2014
Messages
61
Reaction score
25
Location
UK
VCDS Serial number
C?ID=163029
Have a look at the central locking.........you can set it up so the car locks at about 10 mph so you should be able to find a feed that way.........

Interesting, problem is that is done by the door module and doesnt stay live - I'm going to look into that more thanks


^^^^^^^^ So why isn't the trigger for the SS function an acceptable surrogate of vehicle movement?

Because SS is unpredictable and doesn't always work when the vehicle has stopped. I need something that works every time.

It would be easier to find the combination for Autohold without EPB - I'm convinced it sits in byte 9 and 19 (I need to check that to 100% on my pc) it maybe quite probable that the coding combination is protected so Autohold cannot be coded without EPB

thanks for everyones input so far
 
   #6  

DV52

Verified VCDS User
Verified
Joined
May 16, 2014
Messages
5,469
Reaction score
5,934
Location
Melbourne, Australia
VCDS Serial number
C?ID=194404
Because SS is unpredictable and doesn't always work when the vehicle has stopped. I need something that works every time.

It would be easier to find the combination for Autohold without EPB - I'm convinced it sits in byte 9 and 19 (I need to check that to 100% on my pc) it maybe quite probable that the coding combination is protected so Autohold cannot be coded without EPB

thanks for everyones input so far

OK - how about the trace from one of the speed sensors that are connected to the ABS? Regardless whether the speed sensor is variable reluctance, or digital type - since all you need is to detect movement (regardless of speed). it could be a possibility - perhaps?

You would need to be very careful not to load the sensor too much, but if it's fed into a high impedance device so that the additional parasitic load was undetectable by the ABS, it could work

Don
 
Last edited:
   #7  

Vasco Ferraz

Verified VCDS User
Verified
Joined
Jan 31, 2017
Messages
188
Reaction score
119
Location
Portugal
VCDS Serial number
C?ID=288561
Uwe already gave you the best tip.

Sniff the canbus for vehicle's speed.

A canbus shield and an Arduino will do the job very easy and very cheap.

Then:

if (speed >= 1) // You should confirm how speed variable is encoded... This is just an example.
{
relay_on(); // 12V
}

else relay_off(); // 0V
 
Last edited:
Back
Top