So I have a 1992 Toyota 4runner with the 3.0 and an auto trans. It won't shift into overdrive. I've searched on here and found some threads but no real answers were solved.
I read there is 3 major problems that can cause the overdrive not to engage 1) coolant temp sensor. 2) tps sensor 3) trans oil temp sensor. I have no symptoms of running rough or I don't not have any flashing codes. The only thing is it won't shift into OD.

I replaced the coolant temp sensor today. No change

I'm going to swap the tps tomorrow.

Does anyone else have a suggestion or solution ??

Thanks in advanced

 

I would recommend the tranny oil temp sensor over the TPS.. O/D will only kick in when the tranny fluid is at a certain temp so TO ME, it seems logical to replace the tranny sensor first. Not very informative, but that's all I got...

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does the engine get up to normal operating temps? I had a 3.0 that wouldn't shift into overdrive because the thermostat was cut out of it in order to keep from overheating the motor because the previous owner put the head gaskets on the wrong sides. I learned all this after 5 speed swapping.

 

This! faulty thermostat is pretty common.

 

So Brando, is it the engine coolant that must reach a certain temp before you can shift into O/D? I always thought it was the tranny fluid. . The reason I say that is because I can let my truck warm up to operating temp before driving and it still takes a few miles until O/D kicks in. I can let it warm up completely or start it and take off and it will shift in roughly the same spot every time.

 

Engine coolant, not transmission.
www.autoshop101.com / technical articles / at24

Before going to the effort and expense of replacing a TPS, why don't you do a direct end-end test? http://personal.utulsa.edu/~nathan-b...34electron.pdf (That's one of the big advantages of having an automatic - Free TPS test!)

Remember that there are at least three temperature sensors (CSI Timer, gauge sensor, and ECT); are you sure your replaced the correct one?

 

I went off the fsm and replaced the water temp sensor. But after more research, I have found that I don't have 1st or OD. Now I have heard that it may be a solonoid issue, . I just need to find out what solonoid controls 1st and OD

 

Ok my problem is solved!! It was a solonoid issue. Turns out, my lock up solonoid was broken. The head that goes into the valve body was physically broke off at the head. Techniqly it was still operating electronically so it did not throw a code, but was just hanging there when I dropped the trans oil pan. I swapped in a new solonoid. Good as new!! Hopes this helps someone!

 

blah nm