Weird trans issue, A/T, 7MGT

[Devin LeBlanc]

This recently started doing this just yesterday, Transmission shifts fine no slipping at all in any gears, From a stop then start rolling trans will not shift into 2nd gear, It is very delayed about 25-30 seconds and some times skips 2nd and goes straight to 3rd. However once in 3rd I can downshift the selector to the 2nd position and it will downshift into the appropriate gear, also in 3rd with O/D off it will kick down into 2nd as well and then shift up to 3rd like its supposed to. The fluid has been checked, filter was replaced 2k ago along with fluid, I have done a manual test on it and everything checks out as supposed to.

Wondering what could cause a very long delayed up shift from 1st to 2nd and some times it will skip 2nd and go right to 3rd. I have another ECT computer I will try as well but Im thinking its a solenoid/electrical issue as there are no other problems..

Anybody else have this problem?

Thanks,
Devin

 

[Nick M]

I will get back to you.

 

[Nick M]

Does the speedo work? That signal and the TPS tells the trans when to shift. Unplug the range selector at the transmission. Drive it and see if it shifts normal.

 

[Devin LeBlanc]

Yes the Speedo works and the TPS is in spec per TSRM. Im dropping in a 7mgte into a customers car at the shop today so once im done with that ill throw mine up on the lift and try unplugging the selector

 

[Poodles]

Have you checked for codes? http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AT&P=13

 

[Nick M]

If it drives nomral while unplugged, the problem is control and not the transmission itself.

 

[Devin LeBlanc]

I did not have a chance to work on my supra at all yesterday, I just got home from the shop 2:00 am for the 3rd night in a row.. Did a full motor build on a 88 tubo and a trans swap, head bolt retorque, valve cover gasket and tune up on a 91 turbo. Have to finish the 91 up tomorrow but then should have a chance to look at mine hopefully.

Yes I have checked the ECT computer for codes. There are no codes stored.

 

[Nick M]

Wait, you said you are using a manual trans spec'd ECU in the other thread. It has to have signals from the TPS and speedo. That replaces the governor valve and throttle valve. If you unplug it and it runs normal, that is the problem.

 

[Devin LeBlanc]

I have been running it for 4 months like this with no trans issues. A few 12 sec drag passes as well

 

[Nick M]

Unplug it and drive it. What is the result?

 

[Gunnar]

Doesnt the Auto ecu send a pattern on-of code through a few wires to the TCU to tell it how much throttle % you have? I bet it's not like that on the manual ecu.

 

[Devin LeBlanc]

If I unplug the ECT computer it drives fine and passes the manual test. You want me to just unplug the selector switch? I am running a A/T ECU but I have run in the passed a M/T ECU with no codes and all functions working. I really don't care, Im just saying I have done it and it worked fine, so if you have not done it then don't say it wont work unless you have tried it.

 

[Nick M]

If I unplug the ECT computer it drives fine and passes the manual test. You want me to just unplug the selector switch?

Nope. That is the same thing. It ensures you won't have to pull the trans and do any sort of a tear down. You would actually pull the pan after doing pressure test first, but you can't be certain even with the band and clutch chart what is wrong. Unless you don't have reverse and everything else works for example.

I am running a A/T ECU but I have run in the passed a M/T ECU with no codes and all functions working.

I thought you were running a manual.

I really don't care, Im just saying I have done it and it worked fine, so if you have not done it then don't say it wont work unless you have tried it.

This is just full of logic. Now that the sarcasm is out of the way, if it runs fine unplugged, you have an electronic control problem. That should save you time and money.

 

[Devin LeBlanc]

Doesn't matter what ECU I run so back on subject, I think its an electronic problem as well. Loose wire or short somewhere.

The manual shifting test tells me that the solenoids are fine as it uses s1 and s2 for 1st gear and 3rd and both together for 2nd.

When I got my car running I ran a M/T ECU for 3 months with a A/T trans, car and harness, the kick down functions coolant temp based shifting and shift schedule was all fine and functioning per TSRM, No codes in the transmission computer or engine computer

 

[Gunnar]

I've run an ecu without those outputs, and what you get is straight from 1st into third. Second is bypassed.

 

[Devin LeBlanc]

okay, then I guess my ECU is magical.

Anyways im pretty sure its the 2nd gear one way.. Time to pull it apart for a full rebuild