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


  1. This is excellent stuff! I'm trying to do this with a 1995 1MZ-FE A/T ECU (for a manual swap) and it's similar on the inside, except there isn't a "X752" or corresponding "R752" resistor or component there. Closest I have is X952 and R952 components - may have to take a stab and see if it works!

  2. Hello sir can i disable knock sensor from the 3vz-fe A/T ecu? If yes please help me how to do it please