Experimenting with bypassing the AT 4th gear prohibition when cold

[bronsin]

I have the ECHO 2001 Servic Manual and it shows the ECT switch as screwed into the left side of the cylinder head under the plastic valve cover.

Is it the same on the yaris?

The chart for the resistnace values seems different.

[CTScott]

Originally Posted by bronsin

I have the ECHO 2001 Servic Manual and it shows the ECT switch as screwed into the left side of the cylinder head under the plastic valve cover.

Is it the same on the yaris?

The chart for the resistnace values seems different.

The Echo may not have the same sensor, but the placement is the same. It is on the left side of the cylinder head below the large wiring loom that sits between the engine and the battery. The picture below shows the sensor on Crashy (the non dirty one in the center of the pic). The connector has a pink and a blue wire.

ECT Sensor.jpg

The pink wire is a ground, so you can just connect a wire to the blue wire and run it through the firewall (see my cruise control DIY for instructions on going through the grommet above the ECM for the easiest way through).

Here is a close-up of the connector:

ECT Connector.jpg

Connect the wire that is connected to the blue wire to one leg of a normally open momentary switch. Connect the other leg of the switch to a 300 Ohm resistor (270 to 420 Ohms should work if you cant find a 300 Ohm one). Connect the other side of the resistor to chassis ground. Here is mine (prior to heat shrinking). I did not have a 300 Ohm resistor handy, so I connected two 150 Ohm resistors in series. The blue wire connects to the coolant temp. sensor's blue wire and the black wire connects to chassis ground under the dash:

ECT Bypass.jpg