Previa Gl Cold Auto Gearbox Issue

[Gruber]

Hello all,

I have been reading nearly all the posts on here and I have learned lots about my own car! Thanks to all. I have a 1992 Previa 2.4 GL Auto and it smells of petrol inside. Now I have a good idea why. :-) That's not what my post is about though.

I have read several posts on here about auto gearboxes but not found my specific problem anywhere. My Previa's gearbox functions perfectly ONLY once it has warmed up. This takes about 5 miles on a cold day. Before it is warm it will not change into top gear so I end up driving to work (about 5.5 miles) in second gear. This is doing my fuel consumption no good at all and I don't like the fact that something is clearly wrong.

The place I take it to has changed the oil but it has not fixed the problem and he doesn't know what's causing it (or seem to have any ideas at all).

Does anyone have any ideas why my Previa will not change into top gear until it's warm? Changes between first and second are fine and normal even when cold, it's just top.

In case you ask... I leave my overdrive on all the time unless I want to engine brake down hills.

Thanks in advance.

[propnut]

This is quite correct. The ECU monitors engine temp and only allows a shift to top gear when the correct temp has been reached. Obviously the colder the day the longer this will take and if you have the heater on longer still as this slows down the heat up process.

[Gruber]

Thanks for the reply. I am going to change the thermostat as I think the ECU is being told lies by the thermostat!

[propnut]

Thanks for the reply. I am going to change the thermostat as I think the ECU is being told lies by the thermostat!

The ECU has no direct comms with the thermostat. The info comes from the water temp sender at the top right front of the engine. It has a green connector on it. If you are finding that the car is taking excessively long to warm up it could well be that either the thermostat is stuck open or some muppet has taken it out to disguise an overheating issue.

The thermostat is designed to open at 82 degrees celcius.

Good luck