Trying to copy PWM based transmission range sensor circuit

[Gatecrasher]

Has anyone got any idea what microcontroller might be on this Ford transmission range sensor? Looking to copy the circuit for a different application. Could do it with an Arduino and an external 12v regulator but I really like how compact this is.

6F35TR.jpg

[delcowizzid]

Most of the work is probably done on the actual linear hall effect sensor .they are programmable and have there own eprom inside the 3 wire hall sensor

[delcowizzid]

https://www.melexis.com/en/product/mlx9 ... tch-switch

[Gatecrasher]

That's cool. I didn't know something so basic was so customizable on its own.

I really only need to simulate the output from the sensor. I think I found a way to do it with an Arduino. Found one that'll take up to 21 volts on its input pin. Just need to figure out how to dial down the PWM output to the range I need. Hopefully not too hard.

[Gatecrasher]

That was unexpectedly easy.

Found out the Arduino Nano R4 can take 6-21v as input. The F150 PCM I'm using has a dedicated 12 volt circuit for the transmission range sensor. So it was just a matter of hooking up power, ground, and PWM from the PCM to the Arduino. The code is ridiculously simple too. I got it from here. https://www.pschatzmann.ch/home/2023/07 ... no-r4-pwm/

Code: Select all

#include "pwm.h"

PwmOut pwm(D3);

void setup() {
  //period 50us = 20000hz; pulse 0 us = 0%
  pwm.begin(125.0f, 0.0f);

  // set 20%
  pwm.pulse_perc(20.0f);

}

void loop() {}

The service manual explains it rather well. The trans range sensor outputs 125 hz PWM signal, and varies the duty cycle per gear position. These are the values for a 6R80 F150. The values may be different for other transmission types, but the concept should be the same. It'd be pretty easy to rig up a button to cycle through the different values. I don't need that for my testing yet.

P 8.0 — 25.8
R 30.50 — 39.31
N 40.54 — 52.49
D 54.35 — 71.15

PWM_hack1.jpg

PWM_hack2.jpg