I’m currently in the process of installing an ADU7 on an Is300 and I seem to have hit a bit of a snag when it comes to wheel speed. I had read in the manual about wiring the ABS sensors to 12v and then to a Digital input with a 200ohm pull down, and i’ve done that but i’m having no luck.
I also attempted wiring them as typical VR sensors and didn’t get a reading from them either. I’m curious if anyone has succesfully done so with wiring a sensor directly to the ADU or if i’m going to be stuck going with a Wheel speed to Can adapter.
I came to the conclusion despite saying that it’s possible. It isn’t. My assumption is the VR modules they’re using don’t work with the typical abs sensor. I was suggested to go to a wheel speed to can box and at the price they wanted I just ordered an output hall effect sensor for the trans.
Please share your ADU project and a diagram showing how you connected the sensor to the ADU.
There are three types of ABS sensors: VR, Hall, and MR. You need to check which type you are working with, because each requires a different wiring method.
Hall and VR sensors are straightforward to connect, but MR sensors are more complex. An MR sensor is a current source, while the ADU measures voltage. Therefore, the MR sensor requires a +12 V power supply, and the signal must be fed to the ADU in parallel with a pull-down resistor matched to the sensor’s characteristics.
Choosing the correct resistor without a diagnostic tool is very unlikely, so using an oscilloscope is essential during the entire procedure.
The MR ABS sensor also has polarity, so it is important to connect the power supply and the signal to the correct terminals of the sensor. The voltage should oscillate between 2 and 3 volts, with 2.5 V being the threshold point.