Question on switching out the TCU on a 93 Q45?

[SUBZERO]

I have a 1993 Q45, and im in the proccess of switching out the TCU forone out of a 94-96 because i want to have the first gear start TCU.are their any modifications that has to be done for this to be doneor do i simply just plug it in ? thanks for any input!!

subzero

[Infinitiguy19]

Straight plug and play or Bolt-on.

The only significant difference which I am sure you read about is the 94-97 Transmissions having taller (Higher ratio) first and second gears, Which would make the timing a bit off (The way it shifts).

[Q45tech]

Only 90, 91, and 92 Q45 have 2nd gear start under partial load. The 1993 already has 1st gear start from factory unless someone has mis replaced TCU with an earler year unit.

[Q451990]

Only 90, 91, and 92 Q45 have 2nd gear start under partial load. The 1993 already has 1st gear start from factory unless someone has mis replaced TCU with an earler year unit.

Which I would normally say is unlikely, but in Fairbanks Alaska - it may have been done for better control in snow and ice? The first gear start TCU for the 1993 Q45 should have a part number of either 31036-64U20 or 31036-64U75. The U75 is pretty rare and was a countermeasure TCU installed in the field for t/c shift shock that could be attributed to any other condition...

Heath
Modified by Q451990 at 12:19 AM 6/29/2009

[lino]

Later TCU part numbers:

31036-68U10Prod.M/Y: 02/93 - 07/95

31036-67U00Prod.M/Y: 07/95 -

[SUBZERO]

Thanks Lino, i appreciate the part #'s. So either one of these part numbers will work in my 93 model!? The reason im replacing my TCU is becauseQ45 tech said it sounds like the cause for the problem im having, afteri described to him what my car was doing.

This was last year and weather in Alaska is now permitting me to startaddressing the problem again.There was a clicking sound coming fromthe transmission area that puzzled me.It doesnt matter if the car is startedor not, if the key is on it does it.When i first heard the noise i had just bought the car and it wasnt running yet.

Well a year later the old motor was out and a rebuilt one put back inalong with a rebuilt transmission.The first time i fired it up the sameold clicking noise was still evident so i knew it wasnt the transmissionbecause i put in a different transmission and it was rebuilt!

I drove it and the rpm's were higher than they should be at 45 mph(around 2500-3000) if i remember correctly, and it had no punch to itwhen you got on the accelerator. It wouldnt kick down and rev up like acar does when you get on it, it just slowly got up to speed.Anyway itwas said to be that it was stuck in 3rd gear fail safe mode.So here i am a year later trying to get a tcu to try and see if thatfixes the problem.

Q45 tech thinks that might be my problem and another memberhad the same trouble a few years back and he said replacing theTCU fixed his problem. sorry so long just wanted to give you guysa idea of whatn im doing and why.

thanks, subzero

[Q451990]

Just remember that the 90-93 had the same transmission gearing, but only the 93 had first gear start. The 94-96 had a different gear ratio. So - the only correct TCU for your car is one with the part number I posted. The others may work, but you may find weird issues at redline. I would look for the correct one... they seem to be readily available in the US at http://www.car-part.com for $35 and up.

Heath

[SUBZERO]

i appreciate the help!