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plowskxc

Won't Shift To Overdrive

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Hey guys, this is my first post. I just bought a 1989 corolla 4dr auto. I am having a problem with the car shifting into overdrive. When the temperature on the temperature gauge is below the cold line, the car will not shift into overdrive until the gauge gets just barely above that line. When I drive on the freeway the car hardly ever gets past this line, especially in the cold mornings. City driving however the car stays at what seems to be normal operating temperature. Anybody knows whats up? Thanks for you help!

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Hello and Welcome to the forum.

 

The transmission not shifting to overdrive when cold is normal - it is partly due to make sure that the engine gets a chance to warm up (higher revs) quickly and get into optimum operating temps.

 

As for not heating up on the highway, but heating up fine in the city - that is not a good sign. Mostly likely means a stuck thermostat. You could potentially have a bad ECT sensor as well - this could give false readings to the ECM.

 

Do you remember when the cooling system was last serviced? What kind of coolant was used - Toyota Red or the Green stuff?

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Im not sure when it was last serviced, I have maintenance documentation and I will check it tonight but as far as the coolant goes, its green so im assuming its the regular store bought coolant

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Might want to start thinking about doing a coolant drain and refill - maybe a flush. Some green dyed coolant is silicate free - some are not. Toyota waterpumps and radiators don't take very well to different coolants, unless they have been serviced regularly. My personal experience with Toyotas tell me that unless you stick with Toyota Red coolant, stuff starts to fail pretty quickly.

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I drained and flushed the coolant and put the toyota red in but it did not fix the problem and almost seemed to be worse when I'm on the freeway. When I drive in the city at slow speeds the car's gauge warms up like it would normally but then when I hit the freeway it will cool down and go below the cold line causing it to shift out of overdrive. What should I try next?

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I would have changed the thermostat at the same time - since you already had the cooling system drained. That would be my next guess. ECT would be another possibility - hard to say at this point, unless you check the sensor.

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I would suspect the thermostat is not the correct temperature setting.

Also the fan could be shorted and on all the time, causing the engine to stay cool, when it should be warmed up.

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:rolleyes: change the temperature sending unit for the computer, if it isn't reading right the tranny won't shift into overdrive

c
Hey guys, this is my first post. I just bought a 1989 corolla 4dr auto. I am having a problem with the car shifting into overdrive. When the temperature on the temperature gauge is below the cold line, the car will not shift into overdrive until the gauge gets just barely above that line. When I drive on the freeway the car hardly ever gets past this line, especially in the cold mornings. City driving however the car stays at what seems to be normal operating temperature. Anybody knows whats up? Thanks for you help!

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