Sunday 24 December 2017

TOYOCOM :: playing with contact pins in the DIAGNOSIS box

With the TOYOCOM & TOYOFAN tools it is now possible to do more than before with the OBD1READ. This takes advantage of what the DIAGNOSIS box offers by default and allows the user to expand the inputs using empty spaces when availalbe.

Sometimes, depending on engines and wiring harness variants some mandatory wires have been omitted from the wiring harness and require to be added so the TOYOCOM tool can be used at it's fullest. This can be accomplished with simple tools without removing the wiring harness from the car.

Getting contact pins, 2 ways to do it

  1. cut off a spare diagnosis box at the junkyard and reuse it's contact pins.
  2. use brand new contacts that you will crimp and solder to new wires.


I will only describe how to work with new contact pins in this post, the theory on how to pull contact pins from a diagnosis box is described in the later steps. 

You can buy suitable contact pins online from Digikey. A123029CT-ND on digikey

The tools and parts I used.

Getting the contact pin on the wire

Soldering is used to compensate for the loose the crimp tool may leave. 

Getting the new contact pin into the diagnosis box

Hold the diagnosis box so you can read 'DIAGNOSIS' (not upside down.)
 Be careful so the contact pin 'wings' are facing up

You will hear this sound when the contact pin locks right.

Pulling out contact pins from the diagnosis box (applies to BLACK and GREY boxes)

Position the diagnosis box facing you and so the cover sits at your right
 Using the precision flat screw driver you will pry the lock teeth toward you.
 While you are holding the lock teeth with the screw driver you will use another hand to pull the wire from beneath until it is totally out of the box.

Closing the clam shell in the end.

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.

Friday 1 September 2017

3VZ-FE ECU modification : disabling A/T logic

Most 3VZ-FE ecu found are A/T variants. 

Due to the scarcity of M/T ECUs tricks have been developed to keep an A/T ECU from throwing error codes while using it on an M/T car. those strategies have been performed in the wiring loom but it can be performed surgically from the inside which feels to me more desirable.

A/T logic can be shutdown from inside with a handful of steps

Thanks to Toyota for their 80s and 90s ECU design, for splitting key tasks across multiple processors. Namely Engine management, transmission management and knock control. this allows us to take away part of it's logic at it's root while not affecting other processors work. 

Circled in red are locations where work need to be carried out.

tools required

  • the ECU already pulled out of the car, so all tools you can think off for this
  • screw drivers
  • cutters
  • Soldering iron under 100 watts
  • tweezer to hold surface mount resistors


  1. remove A/T processor quartz X752
  2. change engine processor resistors arrangement to match known M/T arrangement R752 goes into R751, failure to do so might bring and engine error 16

1. X752 needs to be cut off from the board using cutters

X752 needs to be cut off from the board using cutters

2. R752 needs to go in place of R751

R752 needs to go in place of R751

Step 2 is the most challenging ,you need to get a surface mount resistor free and solder it on another location. if you don't already feel confident doing so please don't screw your ECU for the learning. find someone who can do it if in doubt.


  • transforms a near worthless A/T ecu into a desirable M/T unit.
  • no more need to fool the ECU into neutral or simulate shift solenoids
  • no more A/T error codes displayed when pulling engine error codes

Saturday 19 August 2017

TOYOCOM : pre-production teaser


A replacement for the OBD1READ is brewing since a fairly long time and is now into beta testing.
The new device is meant to replace the earlier OBD1READ 22p and bare. it allows to get the same toyota obd1 data stream and more. offered with the plug and play connector only, it aims to use  every wire available in the cable.depending on the particular car, those diagnosis box contacts may already be populated by other systems, in which case I suggest thinking carefully if you want to modify the diagnosis box pinout or grow one exclusively for usage of TOYOCOM.
only connections present in the plug and play cable.

Externally the new tool remains nearly the same ,retaining it's blue clear case. a yellow led was added to let the user know when the obd1 data stream sent by the ECU is received correctly by the tool. This feature allows for better troubleshooting.

TOYOCOM & OBD1FAN  devices are compatible with the already existing TOYOBD1 application and basic usage is similar to the OBD1READ. TOYOBD1 on google play 

the OBD1FAN variant which additionally allows radiator fan control .

Pre-production TOYOCOM Features

  • Ligth up a yellow led when the obd1 data stream is active and properly received by the tool.
  • activate/deactivate the obd1 data stream from the android application
  • read the obd1 data stream when active , sending each field directly. this improvement over the OBD1READ allows to see the data on the screen when it is fresh instead of 1.3s later.
  • activate/deactivate ECU error code output
  • read the ECU error codes and display them in the android app with a textual meaning
  • lock ignition timing when conditions are met, allowing to adjust base ignition timing if applicable
  • read battery voltage 10 times per second
  • read 1x 0-20v analog signal 10 times per second
  • *read up to 2x  0-1000hz frequency signals 5 times per second
  • *read up to 4x 0-5v analog signals 10 times per second
0-5v analog inputs into TOYOCOM

0-5V analog inputs suggestion

  • THA or PIM sensor, or all other missing from the obd1 stream
  • Wideband AEM gauge output signal
  • custom added sensors, oil pressure, fuel pressure, additional temp sensors,exhaust back pressure sensors,etc
0-1000hz frequency inputs into TOYOCOM

frequency inputs suggestion

  • IGF signal, gives RPM and ignition coil dwell time
  • SPD signal, gives differential rotation speed
  • one injector negative wire, gives injector PW duration
  • VVT solenoid one equipped engine. tells us VVT usage
  • monitoring IGF,SPD and injectors allows to calculate fuel MPG in the android app

0-20v analog inputs into TOYOCOM

0-20V analog inputs suggestion

  • TT signal when available from the A/T ECU ,tells the selected gear
  • dashboard water temp sensor
  • dashboard oil pressure sender unit
  • dashboard fuel level sender unit

 *some inputs can do both frequency or analog inputs depending on configuration in the android application


Pre-production OBD1FAN Features 

  • everything TOYOCOM does
  • control radiator fan relays according to readings either from the obd1 stream or direct sensor readings
  • warn the user of an overheating or malfunctionning fan condition through dashboard light bulb

preliminary OBD1FAN wiring diagram


New use cases handled by the new tool 

  • Allows to directly read sensors we could not get information from in the obd1 data stream.
  • Allows to directly read sensors that you added, oil pressure, fuel pressure, etc
  • Allows to use on earlier toyota EFI cars with direct readings. giving partial support into TOYOBD1
  • Read ECU error codes. 

OBD1FAN fan control features

  • Allow to specify the Fans activation and deactivation temperatures
  • Allow to control fan activity from obd1 data stream or direct sensor readings for earlier cars
  • Allow to engage fans in a preemptive mode meant for traffic jam and track usage.
  • Allow to disengage fans below a set voltage,( helpful in winter cold starts or alternator failure) 
  • Allow to warn the driver of an overheating condition past a set temperature

Monday 24 April 2017

Electric Power Steering conversion Phase 1

Today I'll share with you how I converted my power steering system to an electric power steering system on my AE102 corolla.

This is only a phase 1 as I want to implement variable PS assistance based on car speed. this would be covered in a second phase later on. This current system is in use on my daily driver since autumn 2016 and was used everyday in the canadian winter since then without failures.

Reasons for going on with this

  • totally disconnect the engine and PS system allowing for a more wild engine choice when space would not allow it otherwise, makes for easier future engine swaps. 
  • allows to turn off enterily the PS system for drag racing. giving an advantage vs regular driving. drops the rotating masses attached to the crankshaft and power losses.
  • allows you to enjoy a different steering sensitivity by the adjustment of a knob and find the spot where you feel best according to you particular car. allowing to take away the spongy steering feeling toyotas are know for.

Parts needed.

  • MR2 turbo electric PS pump motor and it's immediate hydraulic fittings.
  • custom bracket to hold the PS pump motor to the car.
  • PS fluid reservoir and low pressure hoses to reach PS pump motor
  • Hydraulic hose to join the PS pump motor and the steering rack.
  • 80a adjustable DC Motor controller. 
  • 80a fuse
  • 80a automotive relay 
  • 8ga wiring to reach car battery, fuse, relay and PS pump motor.
  • 18ga wiring to reach relay's coil and +b 
here is the DC motor controller I am using since last autum without issues. comes with it's tuning knob
e-bay 2000W PWM Motor Speed Control


Electrical wiring diagram.

no details are given on the PS pump motor wiring color yet

Pictures of the installation are yet to come when time allows.

Wednesday 15 March 2017

TOYOBD1 :: quickest way to test TPS operation

!! After doing this test procedure make sure to erase ECU error codes because unplugging the TPS while Ignition key is ON will store an error code. !!

This technique is only meant for 4 wires analog type TPS.
Typical 4 wires Toyota TPS

4 wires are reaching the TPS

  1. E2 is a sensor ground 
  2. IDL is telling the ECU if the throttle is at rest
  3. VTA is the output signal telling the throttle opening angle
  4. VC  is a sensor reference voltage, should be 5v or pretty close

First make sure the IDL switch is working inside the TPS

Without the Ignition key ON, unplug the TPS connector.
Using a multimeter you will test for continuity between E2 and IDL when the throttle is at rest. if you open the throttle plate big enough continuity will be loss, this is expected.
using a multimeter I'm testing for continuity between E2 and IDL

Testing with TOYOBD1 the ECU and wiring for proper operation

notice the absence of IDL flag here
With the Ignition key ON and engine not running, 
unplug the TPS connector. 
Launch TOYOBD1 and connect to your OBD1READ device. 
make sure you look at the TPS cell.
with no TPS connected you should get such readings
The IDL flag will not be shown, this is expected.


LOOKING INTO THE TPS CONNECTOR. with a jumper in place

notice the presence of the IDL flag
Now using a jumper wire you will bridge E2 and IDL.
you will get this reading in TOYOBD1, the IDL flag will be present.
if you don't get the IDL flag to show something is wrong with the wiring between TPS and ECU, or the ECU is damaged( less likely )


!! After doing this test procedure make sure to erase ECU error codes because unplugging the TPS while Ignition key is ON will store an error code. !!

Tuesday 14 February 2017

Mandatory skills before ECU tuning

Lots of people want to tune petrol EFI engines for themselves

As modern and software oriented it may seems, it requires of people godly troubleshooting skills when things don't go as planned. Without all of those skills you will always depend on a skilled folk with dwindling patience who'll end up terminating your friendship with him.
Here are the most important to me

When creating something new it's rarely expected to work right the first time

Be the person who can take on challenges, not the one asking others to fix it for free and take the glory.

Buy yourself a fire extinguisher if is not done already.

General DC electrical skills

- master iron soldering, twisting wire is not allowed
- understanding the wire colour naming convention.
- understanding how fuses work and enjoying their benefits
- understanding how relays work, there will be an awful lot of them ahead
- understanding your engine wiring diagram perfectly, if you can't say why it is rigged this way try again.
- being able to use a multimeter to read voltage,impedance,frequencies and capacitance.


0- understanding engine firing order and being able to place spark plug wires accordingly
1- being able to test for spark events at the spark plugs (getting a spark occurring outside the cylinder head for tests)
2- being able to tell when an engine does not run on all it's cylinders and locate which ones
3- being able to read spark plugs colours. (being oily, rich, lean, and more importantly variance accross cylinders)
4- being able to properly install a timing belt or timing chain
5- know what is ignition advance and ignition retard.
6- being able to use an ignition timing light
7- being able to locate TDC on the reference piston on an engine with a test rod(making sure the reference point on the harmonic dampener is true)
8- being able to adjust an ignition distributor


- understand what composes the fuel delivery system and identify which part on your car is each one(appearance varies from one implementation to another)
- identifying fuel leaks and fixing them appropriately
- being able to measure fuel pressure with a gauge
- understand how to adjust a fuel pressure regulator if needed
- knowing the various smoke colours that can come out of a tail pipe and their origins
- knowing what is a rich and lean mixture
- detecting various bad analog sensor readings
- being able to test injector impedance
- understanding how the universal narrowband oxygen sensor works and testing
- understand how to install and read a wideband oxygen sensor/gauge
- rough injector operation testing
- understand what the injector duty cycle means ,measuring/calculating it would be even better


- understand the concept of engine volumetric efficiency ( VE )
- understand the concept of [RPM x VE ] and  [RPM x pressure] mapping for fuel and ignition
- understand what is engine air flow
- understand what an air flow meter outputs and interpret it's reading
- understand what forced induction does to engine air flow

SOFTWARE use skills 

- know what is a COM port on a laptop computer
- being able to find the COM port # you'll be using when tuning. those things change from time to time :)
- being able to use the data logging interface offered by the ECU,if available
- being able to locate data log files on your computer and read them with a spread sheet software

With those skills you should be able to troubleshoot many basic engine related issues and should avoid being a pain in the ass to someone else who does know. there is far more to be known than this, If all of this is already boring, don't bother going deeper. :)