WHAT'S THE BIG IDEA
Having modern day diagnostic features on an car is very useful. On a +30 years old car it is a luxury that is rarely found. For Toyotas there is hope now. Using the toyocom 'universal mode' you can get a fair level of information out of our mid 80s toyotas.Doing so requires of the car owner to do some electrical work to splice into signal wires we care for. A compromise was made to leave the wiring harness untouched. It may be more ambitious but certainly not out of the reach of the DIYers. What requires to be done is to solder wires on the underside of the ECU main board, exactly where the ECU connector are soldered. This location gives us acces to every wires going into the ECU and is conveniently labeled on most toyota ECUs.
RANDOMNESS STRIKES
Believe it or not, while working on this blog post a friend passed by with a beaten up mr2 while being in transit to somewhere else. It was shear luck,so we took the time and tried the modified ECU on it!The car was in really bad shape but running,no exhaust with the blue top 4A-GE not running on all cylinders. we were able to get our readings while being quick at it to not wake up the city neighbors.
WHAT YOU CAN EXPECT IN THE ANDROID APP
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mandatory features from universal mode on an early EFI toyota.
- Error codes readout
- battery voltage
- fuel trim
mandatory wires you have to solder
- B+ 12v power
- E1 ground
- T (TE1) trigger error code output
- W check engine light
- VF (VF1) fuel trim
additional wires you should monitor before anything else
- IGT this is the igniter control (for RPM input)
- #10 this is the first injector pair control
- VS this is the air flow meter output
- OX this is the oxygen sensor
- THW this is the coolant temp sensor
reasoning
- having RPM & injector activity allows us to get injector duty cycle
- having the air flow reading tells us about the engine load which is always useful.
- having the oxygen sensors allows us to troubleshoot fueling issues against engine load & rpm
- having coolant temperature allows us to know if we overheat and guess the fueling choices.
WHAT YOU NEED TO GATHER
- a toyocom scan tool from www.zf-scantools.com
- a spare ecu for your engine is best.
- a junk yard diagnosis box, preferably a late black one from an obd2 toyota.
- new contact pins from digikey (only usable with the late black diagnosis box)
- 10 wires of different colours. about 1' long 20ga
WHAT REQUIRES TO BE DONE ON THE ECU
To understand how to install contact pins in the diagnosis box follow this earlier post.
where each wire goes in the diagnosis box
ORANGE = +BRED = VF1
DARK GREEN = E1
NORMAL GREEN = AB
YELLOW = W
WHITE = TE1
BROWN = TT
BLACK = TS
BLUE = TC
PURPLE = VF2
- install contact pins on each new wires you need ( a feet long is comfortable to work with)
- place the wires in the diagnosis box at the specified spaces in the top cover
- Add a shrink wrap sleeve to your new bundle of wires
- Remove both top and bottom ECU cover plates
- on the TOP side,read the labels for the connector pins to know where your signals are located.
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| YOU WILL BE SOLDERING ON THIS SIDE |
where each wire goes on the ecu connector
ORANGE goes to +BRED goes to VF
DARK GREEN goes to E1
NORMAL GREEN goes to VS
YELLOW goes to W
WHITE goes to T
BROWN goes to THW
BLACK goes to #10
BLUE goes to OX
PURPLE goes to IGT
Overview of the work done ot the ECU
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| PLEASE EXCUSE THE HASTY SOLDERING |
- solder each wire to it's matching pin
- reinstall the top cover plate.
- Applying hot glue with a glue gun over your work is suggested for shielding and dampen vibrations.
- connect your ECU to the car and the toyocom into the diagnosis box.
- at this point follow the toyocom user manual given with the tool to start using it.
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