Over drive not shifting in Toyota Yaris 2006

Taimur

We have replaced an automatic transmission in Yaris 2006 but the problem resists i.e, 4rth gear is not shifting(over drive). We have diagnosed it on launch 431 scanner and it shows the knock sensor voltage problem. What can be the cause of this? Any help plz?

praise · Posted: Wed Jul 01, 2009 4:48 pm Post subject:

What engine does your Yaris have? I am seeing that you are from UAE. I am not not sure it would be the same for you as us here in Trinidad we have a 2NZ FE 1.3
What is the mileage and why did you change the transmission in the first place. Is it a new transmission or used one that you put in. A voltage problem is cause by lose or broken wire. You would need a wire diagram to check continuty from ECU to knock sensor. It should carry 3 wires. One is from the ECU to sensor. One would be ground and one is signal.
Also check your overdrive switch and make sure the transmission is getting the current signal when turned on.

Taimur · Posted: Fri Jul 03, 2009 6:45 am Post subject:

Yes the Engine is 2NZ-FE. We changed it because the 4rth gear/ over drive was not shifting and we installed a used one. But the same problem is there. Now how to check the over drive switch is getting the signal or not and where is that switch located. Also we have checked that the knock sensor is even not there. Its missing.

praise · Posted: Fri Jul 03, 2009 11:03 am Post subject:

The overdrive switch is located on the gear shifter. A light goes on the dash when the switch is off. You definately needs a wire diagram for this car. You knock sensor is located on the engine block under the intake manifold. If there is no knock sensor then that would be the problem with the voltage and your engine check light should remain on. Concerning the transmission I am almost certain it is an electrical problem, no current going to the overdrive switch on the transmission. When you change the transmission did you get all the speed sensors and electrical switches with the used one or did you use back your old ones? Your old switches could have been your problem and nothing could have been wrong mechanically with it, so do not throw it away.

Taimur · Posted: Tue Jul 21, 2009 3:10 pm Post subject:

Thanks for your help. I was actually away for these days so cldnt reply. There is not over drive switch on the lever and even there is no check engine light in the meter board. As far as the switches are concerned, there is no speed-o-meter switch in the trans and the remaining sensors were new excluding the selector switch.

praise · Posted: Wed Jul 22, 2009 11:25 am Post subject:

Change the selector switch. This is the cause of the overdrive not coming on.