UDIG3 and 4: on which rail are they grounded?

[parsonsj]

My magnetic wheel speed sensors don't work -- I tried to use a reluctor and sensor from a 2007 Ford. I recently bench-tested a motorsports Hall-effect sensor (VR-09, if it matters) on the reluctor and it works very well.

To switch over to the VR-09, I need to snag a 5V supply, and I'd like to pick up the 5V supply with the same rail that is currently in use by UDIG3 and UDIG4's ground (white/blue) wire.

My ECU is buried underneath body panels so I'd rather not pull the car apart and figure it out. The manual doesn't say.

Anybody know? Or does it really not matter?

Thanks!!

[David Ferguson]

Use the matching ground for the power supply you are using. So if using 5VA, then use 0VA for the ground.

The reason this matters for temperature inputs is that they internally use one of the supplies, and you need to use the matching 0V.

[parsonsj]

Thanks David - that's what I want to do. My question is on which rail do UDIG3 and UDIG4 run their ground, so I can pick up the corresponding 5V supply.

This isn't for a temp sensor -- it's for a wheel speed sensor.

[adrian]

It makes no difference which 0V you use for any sensor input. A sensor that is wired to 5VA can be grounded through 0V A, B or C.

It is good practice to wire a sensor with matching 5V and 0V supplies simply because it is easier to fault find if you need to later on. You should also spread the sensors across the three 0V rails to share the load and also reduce the chance of a sensor fault affecting all sensors in the car.

It is important to note that this doesn't apply for the 5V rails. You need to know which one is wired to your particular sensor and set it in the software so that any float in the 5V supply voltage can be accounted for in the sensor reading.

[parsonsj]

Thanks Adrian.

I've tapped into the 5v supply from nearby pressure sensors to power my Hall effect rear wheel speed sensors. Testing yesterday went well.