1994 toyota four runner not going into overdrive until it is warmed up

Don't give up looking for an answer.
I maintain 4 Toyotas, and all of them do this very thing.
I have learned to live with it.
I have taken them to Toyota dealers, who say there is nothing wrong with them.
I have taken them to independent transmission shops, who have changed the oil and serviced the transmissions, and they were not any better.
So now, I let the car warm up for a few minutes, and it shifts a little sooner.
God bless your efforts.

Here is a diagram for a 1994 pickup. The 4 runner uses the same fuse box, with additional circuits for other options. Fuse 7 would be the same. If you have access to an owners manual, you can reference the fuse box there. Located in the engine compartment.

Make sure u have a good thermostat in it. The engine temp must be at certain temp then a signal is sent to the transmission so it will shift into overdrive. Bought my 4 runner,91, was shifting fine until started getting cold then stopped all of a sudden. Checked the thermostat and it was in but had been gutted which allowed the engine not to warm up sufficient to allow the trans to shift into overdrive. Changed thermostat about $8, hasn't skipped a beat since.

means it's going out or the transmission oil will need to be changed, check the transmission fluid if it is brown and smells likes onions have the fluid changed and the filter, this may not fix it but you may get lucky, if it's the band or clutch assembly you will have to rebuild transmission.

For some toyotas (I own a 1994 4-runner) there is an emissions-control feature that disables Overdrive until the engine is up to full temperature.
In my case, it would get into overdrive, but it took a very long time to get there, especially in winter. Turns out that the thermostat was stuck open, so the engine was running very cold. About $150 got me a new thermostat and now it's all better.

Hope that helps!

That's actually a feature, not a problem. The emissions control system will not let it go into OD until it's warmed up.

If your truck warms up in a normal amount of time, then you're all set.

Last year, my 4Runner started taking too long to warm up, so it wouldn't go into OD for a long time. In my case, it was that the thermostat was stuck open, so coolant was flowing freely even when the engine was still cold. Replacing the thermostat was quick and easy, and it's good as new again.

I would start with replacing your tranny fluid. black is no good. your tranny should hold about 7 qts of fluid. The tranny fluid runs through your radiator to help keep it cool. If your thermostat is stuck closed your eng coolant won't circulate and the coolant will get hotter inside your radiator. thus making your tranny fluid hotter and breaking it down. After time it will turn black from getting too hot. Let your car warm up to normal operating temperture then grab your upper radiator hose. It should be very warm. If not your thermostat is stuck closed.

sound to me like it maybe a faulty sensor in the transmission. take your car to someone with an ODB reader and see if a transmission fault is indicated. you may have to take your car to a transmission shop.

You are going to need the transmission rebuilt.

Did you replace your overdrive cable on the throttle body assembly?

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