greetings. i'm old school when it comes to meters and gauges, i know there's plenty of info available on the CAN, but i'm really the kind of guy that likes to see actual meters. i'm also into metering things that interest me, but likely dont interest most people. ive set up counters and hour meters on circuits such as the fuel pump to get stats on engine run time compared to Ready mode on for example. im interested in tracking the number of times power assist turns on, and the duration. i would like to know of a place i can tap 12v that is only on during power assist (steering wheel turning), whether that is directly off the large 12v wires to the steering assist motor if its switched, or at another control location, hopefully not so deep under the dash or engine compartment the supply doesn't need to allow for much current, only the presence of switched 12v, i can design a circuit that works with that without loading down that circuit. its fairly simple on a conventional power steering system, tap off the pressure switch that tells the ECM to increase idle to compensate for addl load from steering pump. any info would be helpful.
You get that it's not on/off, right? You're going to see zero volts when it's not assisting at all, up around 12-13 when it's giving you max assistance, and everything in between, in proportion to how much torque it measures you putting on the wheel, and tapering off at higher speeds. What are you going to call "during power assist"? If old-school is your thing, you could always try driving around with a chart recorder in the next seat. -Chap
very cool on the chart recorder, that's totally me!!! what i call during power assist would be anything that produces a need for assist left or right, as slight as a lane change or as dramatic as a full left or right turn from stop. the only time i would not be registering anything would be when the steering wheel is straight driving down the road. on conventional steering, the slightest move of the steering wheel increased the high pressure side activating the pressure switch for the duration of the increased pressure. i would think if its varying anything, it would be some kind of pulse width modulation, i've done work with stepper motors that use pulsed DC and DC drill controls that use PWM. so if we are working with variable DC voltage, i would need to get a tap on the motor supply, then monitor the voltage as i steer to determine where i want to create a minimum voltage threshold to activate another circuit to turn on a process counter and hour meter. are you aware of any easy locations to tap the supply instead of digging deep under the dash?
Power steering motor is connected to power steering ecu with two wires. Voltage difference between the wires means that assist is on. ECU is in the driver’s side dash and motor is in steering column assy near steering wheel.
Yes that’s why I wrote “Voltage difference between the wires means that assist is on”. From polarity we know what way assist is turning the steering. But since OP is not interested in knowing that one simple circuit would use just AC-type optoisolator and resistor.
