TOYOTA engine swaps, avoiding wiring job traps

Since I have started developing TOYOBD1 I learned constantly about the 90s to mid 90s OBD1 Toyota ECUs, they all share similitudes.The traps we fall into while doing custom engine wiring jobs are also similar here are a few I have encountered through the years that may save you time and money.

The STA wire

STA is not to be fed with a constant 12v source like b+, it's purpose is to inform the ECU that the starter is engaged while the starter is engaged. feeding constant 12v to STA will fool the ECU into thinking it is cranking all the time, regardless of engine speed.this will make an ECU inject about 2.5 times the fuel it would have injected normaly. in all cases I have seen it is so rich the ignition cannot burn all that fuel, and of course engine performance is bad. Lots of people fall into that trap, stay aware!.

The Batt wire

This one is a constant 12v power source, it is fused and always powered regarless of ignition key position. this is what keeps the RAM (ecu memory) powered at all time. not feeding Batt correctly will result in Error codes being wiped every time the engine is shuted off, and the ECU learning process starts form scratch every time. 

Digital 3 wire TPS (PSW, E2, IDL)

On cars using this system it is important that those signal be wired correctly. those ECUs dont have a real TPS, this TPS design only tells the computer if you are at idle, at WOT , or anywhere in between. this is a lot of guessing and if the ECU senses the throttle is at WOT when it is not it may take bad fueling and ignition angle decisions. a digital tps can also simply go bad and need replacement. found on MT cars 3S-FE,4E-FTE,etc

The E2 wire

This is a special ground,This is the sensors ground, this ground must not be tied to other ground signals directly, doing so may introduce sensor noise or worst.

OBD1READ + TOYOBD1 :: making sure it works for your specific case prior purchase!

There is lots of  combinations to be done so let's clear out if TOYOBD1 will work with yours! Here are 5 steps to find out like a pro.

 

1- Is your car standard and listed under the supported engines list? 

if not, it may be supported but you should ask me advices so that we sort it out.

 

 

2- You need an android device

 

Phones and tablets with Bluetooth capabilities using running Android 2.2 or higher will do.
SD Card external storage capability is highly suggested for use of the import/export features.
take the time to install the TOYOBD1 application and familiarize yourself with the menu and the very informative glossary.

 

3- You need to find 4 signals in your ECU pin out 

You need to know your exact ECU pin out, it may differ from market to market and even from car model to another model WITH the same engine, or between Manual transmission and Automatic transmission. if you cannot find your ECU pin out online you can open your ECU and take a look at the pins label on the bottom PCB. please share your unavailable pin out findings so that we live in a better world :)

when looking at an ECU pin out you want to see TE2,(VF or VF1), E1 and B+. OBD1READ needs those 4 signals to work. if you don`t have a TE2 signal it will not be able to work at all.

 

4- You need to know your diagnostic box on your car( this is where OBD1READ connects )

You need to find it and identify what signals are available there, otherwise you will need to source them elsewhere. The sticker in the cap can be misleading, it will tell you where each signal is housed but it will not tell you if it is present.That sticker is universal for toyota cars of a specific era. The signals you are after are VF1,B+,E1 and TE2 please be careful many persons mistook TE1 for TE2, they are physically near and almost named identically...beware!( no harm to the device can be done if you connect te1 instead of te2)

You need to probe in those spaces with something small enough like a micro screw driver, you are searching for metal contacts. if some are missing, (TE2 is generally the missing one) you need to source that signal from elsewhere. either on ecu pins through new wires or by splicing into existing wires at the ecu connectors. the 1UZ-FE engine swaps mostly always need to take the TE2 signal this way.

 

5- You have found your signals, you can test if they do useful work

Using this test method you can determine if your ECU can be put into obd1 data output. it requires a digital multimeter( a test light is not a proper tool for this)

 Summary

At this time you should have an android device ready with TOYOBD1, You have an ECU that was proven to output OBD1 data when TE2 and E1 are jumped together AND you know where to source your signals.
It is safe to say that an OBD1READ device with TOYOBD1 will work for your car!