Rebuilt Transmission shifts out of overdrive when cold into lower gear and back n forth


#1

I have an Acura CL type S with a rebuilt transmission from 10,000 miles ago. It is a 2001 model. The torque converter went out a 8,000 since rebuild and has been rebuilt again. The symptoms are as follows. When shifting into overdrive and transmission is cold, it shifts out of overdrive into I believe 5th which at 70mph it goes from 2,000 rpm’s to 3,000 rpms and back n forth. It doesn’t do it too often once Transmission is warm. Now the symptoms of this transmission were the same before torque converter went out, and the same now that they rebuilt it again. Its unreal. It is under warranty but the transmission guy’s are stumped and I don’t have tons of time to take it back. I tested the throttle position sensor thinking it might be that, but it’s all good. Any takers? Is there any sensors that control whether it shifts in and out of overdrive when its colder. I’m out of answers here guys.


#2

Does the fluid look ok? And have all the basic tests already been done, the selenoids are verified ok, and the fluid pressure checks out ok?

If so, then before spending a lot of time and money on diagnosis, it might make sense to do a basic service. You might get lucky. Drop the pan, drain the fluid, change the filter, then re-fill with Honda’s recommended fluid. If that helps, but doesn’t solve it completely, then do it again after driving 250 miles. And be sure to ask the mechanic to check for metal filings in the filter and in the drained fluid.


#3

You might want to have them check the coolant temp sensor for the computer.

Normally, the computer doesn’t allow the transmission to go into overdrive until the coolant reaches a certain temperature. This allows the engine to heat up faster to reduce emissions.

If the coolant sensor has failed where it’s sending an erroneous signal to the computer, this can confuse the computer as to when the transmission should go into overdrive.

Tester


#4

ah, warranties on rebuilt trans. if shop is 99% sure it really is a trans issue and not a computer/motor issue affecting trans than they need to give up and refund your money or goes crazy and swap in a different trans.their labor is free, but they might have to buy a different trans. shops dont like that


#5

It isn’t the fluid. There is Honda certified fluid in it. I believe it to be that coolant temp sensor as well. It seems like the computer is confused. It doesn’t trigger a check engine light is what is misleading. Does this coolant sensor if not working properly trigger check engine usually? The transmission worked fine for first 8k miles until torque converter supposed was bad. They pulled it back out and replaced torque converter. But rhe symptoms are the same before the pulled it a second time and now that its replaced. Is that coolant temp sensor tough to get to? I replace the thermostat last year myself. I read a blog on this coolant temp sensor not working correctly and the transmission not wanting to shift into overdrive good. It seems like the most logical explanation at this point. After I drive 20 miles or so it doesn’t shift in and out of over drive


#6

Yeah in with you tester on this. But cavell I don’t think these guys are going to want to buy me a new tranny even if it is under warranty. Although they are the experts and if they cannot figure out the problem should be responsible. Although, it could be coincidental that this sensor is causing transmission to go crazy when colder. Although it is Texas so its hot down here. Haha


#7

Georgesanjose actually selenoids might not have been replaced. I asked the transmission guys if selenoids had been replaced and he was like well we don’t have an inventory on whether its been replaced. I was like gee thanks. It could possibly be selenoid. Although he claims selenoids rarely go out and if they look fine they don’t touch them on rebuild. Plus usually they trigger check engine. No check engine has been triggered yet at all.


#8

Tester, you’re the man! It was the temp coolant sensor, and it’s funny because I replaced that temp sensor a little over a year ago, and it was with crappy Auto zone parts. I got a new one from O’ reilly auto parts and bame, transmission shirfts that way its supposed too! Thanks guys!!