Thursday, 2 November 2017

TOYOCOM :: Adding custom pressure sensors

Adding custom pressure sensors for use with a TOYOCOM device

Today I will show you how to add a third party oil/fuel pressure sensor to an ST205 3S-GTE wiring harness. this sensor is only going to be useful if used with a TOYOCOM device & TOYOBD1 android app. No other system care for it's reading and it cannot affect the engine performance adversely.

ST205 bench harness used for the demonstration

The 0-100 psi oil/fuel pressure sensor we will be using

This sensor is found easily on E-BAY for about 20 CAD each, comes with it's pig tail and can be ordered for various pressure ranges. In the case of most Toyota engines, an oil pressure reading of 0-100 psi seems adequate. Similarly fuel pressure on those engines are not meant to reach 100 psi so this range is fine for both uses.

The pin out if this sensor is very simple. (if in doubt with a particular model ask me)

  1. BLACK = sensor ground (goes to Toyota wiring E2)
  2. RED = sensor reference voltage(goes to Toyota wiring VC)
  3. GREEN =  output signal , this goes straight to the TOYOCOM device only.


The ST205 ECU wiring diagram with today's additions

Show below is the test bench incarnation, only aligator clips wires have been used. In real life solder and isolate your wires The new green wire has been routed in an empty spot of the diagnosis box , into VF2, the matching VF2 pin of the TOYOCOM device can read 0-5v analog signals or frequencies. Red and black wires have been tied to TPS wires due to the ease of locating them, depending on your specific cases those same wires could be had near a MAP sensor also. please ask if in doubt.










You can now plug in your TOYOCOM device and power the whole system

 Now the Software configuration

In the TOYOBD1 app you will need to have already paired and connect to your TOYOCOM device, you will also need to have set the display configuration to see the VF2 input.Then we will be able to apply the sensor curve to this input and get what we want.

Sensor curve for use in TOYOBD1

The curve for use with this sensor is available on dropbox HERE

 Now click/zoom into the VF2 signal cell, it will not have a sensor curve applied yet.
Then press on the 'ADC' button to prompt the sensor curve selector dialog, there are a few key built in sensor curves but the oil/fuel pressure curve is not built in yet and requires to be read from a file.
 Now press on the '...' button to search for a sensor curves, I placed the file into my TOYOBD1 directory, press OK, then back into the sensor curve selector press apply sensor curve.
 At that time the VF2 cell will have changed, it will not show the measurement unit from the selected curve, if you don't have a gauge but text display and wishes the gauge, just swipe left/right on it , it will come.
Whole screen after clicking/zooming out of the VF2 cell. at this point you are ready to see useful oil/fuel pressure next time you go for a drive.