TSX Dual ECU Setup - No need for additional ECT sensor

Currently the typical method of getting proper engine temp measurements on a TSX with the dual ECU setup is to install an additional ECT sensor. The reason this is done is because you can't parallel the ECT input on both ECUs without it skewing the signal. This is because there is a pull-up resistor inside each ECU that creates a voltage divider with the ECT sensor. The ECU is calibrated for a specific input voltage vs temp, so if you change the resistance of the pull-up resistor (like paralleling 2 resistors) then it will change the relationship of voltage vs temp.

Well, all you need to do is remove one of the resistors and then you can parallel both ECT inputs. You should remove the resistor in the TSX ECU as this is just for the gauges. Said resistor is R105. A 1.5k surface mount device (SMD). If this is above your skill level then find an experienced tech that can perform the work. Even if you have to pay someone to do this, it will cost far less than an additional ECT sensor and you won't have to go through the hassle of installing it.

The resistor itself costs less than a penny and a new one can be installed if you ever decide to change back to stock.
Pictured here is a 2004 manual trans TSX ECU.