Yaris 56 plate semi auto

[Dupont]

Hello, I have a Yaris semi auto with 34,000 on clock.

The semi auto part of the transmission is fine.

However, the auto part is very hesitant to change from first to second in cold weather. It has to attempt to do it several times usually and jerks terrible. Once it is warm then it gets much better. It drives well once in gear with no slipping. I gave had new fluid out in so am at a bit of a loss.

Anyone got ideas as to what it might be? I read somewhere about a solenoid?

[zoidberg444]

If it's attempting to change it sounds like the Solenoid is working fine. That the problem is mechanical, not electrical. These semi-automatic gearboxes are always trouble. Almost sounds like the syncho's aren't gripping and it's having trouble slotting the gears in. In the past before i changed my gearbox oil i noticed it in my own manual transmission car that sometimes you had to have a second go or use a bit more force with the gear change when the car was cold.

What gearbox oil did you put in it? Many people on here have had bad experiences with Mobile gearbox oil. I use a 75W90 GL4 semi synthetic made by Comma. It's pretty cheap but from what i hear these boxes prefer the cheaper dino oil because it allows the syncros to grab better.