Turning a 12V 25mA signal into a ground input signal???

I'm a mechanic and don't know that much about electronics. We are currently building a car with a Dakota digital dash which looks for a ground from the brake proportioning valve or the master cylinder fluid level switch to turn on the brake warning light. We are also installing an aftermarket electric E-brake in the car and the control module for it puts out a 12v 25mA signal (+) that's meant to turn on an LED for when the E-brake is on. We are looking for a way to use that 12V 25mA + and turn it into a ground input to the Dakota digital control module so that it would turn on the same Brake warning light. I was thinking it could be done with a NPN transistor but I'm not sure how to build the circuit. It would need some resistors to work without frying right? What resistor values should I use? Correct me if I'm wrong but 12V @ 25mA would probably not be enough to switch on a common automotive relay would it?? (command coil is usually 80-100 ohms). I'm sure this would be a fairly easy circuit for someone that has a better understanding of electronics than I do. Any help would be greatly appreciated. Thanks!

by MrGearHead
November 03, 2019

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