Relay operation with ABS

Hi,
I am planning a project to intrude to the ABS circuit in my car. Basically, to operate a 5 pins relay whenever the ABS in engaged (i.e. the ABS motor is in operation). The ABS motor circuit is shown in this figure attached. The other figure shows where I might insert the relay (just near terminal 16). My questions are; will this setup work, is there enough power to operate the ABS motor and the relay all together, will this setup cause any damage to the ABS circuit and actuator? Note that I can only intrude to the connections outside the ABS unit (i.e. terminals 17, 16, and 19).
I am planning to use a relay similar to one shown **broken link removed**

Is there any other cheap way to sense if the motor is running or ABS is in operation. (Note: the ABS assembly is located in close proximity to the car motor).

That relay would be fine. It takes far less current than the ABS motor.

However, you have to put it in parallel with the motor, not where you have suggested.

If you can't get to the other side of the motor, where it connects to the relay that is there already, you need to put a current sensing device in where you suggested. That has to be a device that can take the 30 A of the supply without dropping more than 0.2 V or so. I suggest a DC current transformer such as LEM | Process Control | Sensors and Transducers | Current Transducers | LEM Current Transducers |LTSR 15-NP. That doesn't introduce any voltage drop at all.

I realise that it is only rated to 15 A, but they aren't damaged by overload, and there is no voltage drop, so it is better to use a smaller rating to get better sensitivity.

Make sure that you understand series and parallel before messing with ABS. Test it at 10 mph or less where you have enough room to stop if it all goes wrong.

Thanks Diver for replying.
These current transducers are not cheap at all. the cheapest I one found is this one Non-invasive AC current sensor SCT-013 (30A max) Non-invasive AC current sensor SCT-013 (30A max) [SEN005] - $9.50 : iStore, Make Innovation Easier for about $15 including shipping. Do you mind looking at this and tell me if it is suitable to directly hook it up to the relay mentioned before.
Sorry, but i am not so familiar with sensors at all.

Thanks for answering me,
I found a cheap current sensor but not sure if it works for me (Model: SCT-013-030 for 30A). Would you mind having a look and tell me if it will work. please find the specs in the picture provided.

That won't work. It is a standard current transformer, that only works on AC.

398-1021-5-ND is a part that can be obtained from Digikey Canada.

Thanks,
The one you proposed works for 6A current circuit and requires a 5V input (which means I need a voltage transformer to install it on my car).
I found this item 398-1038-ND which works on 12 V car supply for 20A primary circuit. Would this work for me???
Sorry to ask again but I am really new to this and i could not find a good reading material on how to connect the sensor to the primary ABS circuit. This item 398-1038-ND has Pins 5 and 6 to connect to the primary input circuit, so does that mean I need to cut through the ABS circuit and connect it to pins 5 and 6 at the location you proposed to me. Please have a look over the attached for datasheet info.

HFares said:

Thanks,
The one you proposed works for 6A current circuit and requires a 5V input (which means I need a voltage transformer to install it on my car).
I found this item 398-1038-ND which works on 12 V car supply for 20A primary circuit. Would this work for me???

Click to expand...

You can't use a transformer on DC.

To get 5 V at less than 40 mA needs a simple to use component called a regulator. A suitable one costs less than $1.00

The 398-1021-5-ND one needs +12 V and -12 V which is more difficult to generate in a car.

All of these are current sensors. They all go where you suggested in the first post of this topic.

The 398-1021-5-ND, or a higher current version, the 398-1029-ND, have a hole in the middle. You just pass the wire through the hole. As long as you put the wire back where it came from, the transducer will not mess things up and you don't need to cut any wires. If you put it on the wrong wire, the ABS will still work.