Diagnose Failure, 4T45E [Archive] - GrandAmGT.com Forum

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AleroB888
10-22-2011, 02:30 PM
Tranny will be rebuilt soon, but I'd like to know which internal part failures are indicated:

1) With lever in "D", Trans can't auto shift into 2nd from 1st at WOT, hits rev limiter.

2) With lever in "2", trans shifts ok into 2nd at WOT, but not from "2" manually into 3rd at WOT.

3) Trans can auto shift into 3rd, but only at low RPM, and RPM must be kept lower than about 2K to accelerate at all in 3rd.
(but it's hard to tell if it's in 3rd or 4th at that point)

I'm trying to make sure nothing electrical can possibly cause any of this, external to the trans.

AaronGTR
10-23-2011, 10:39 AM
could be the programming, at least for the shift points. I had that problem with it not shifting to the next gear at WOT and it ended up being my WOT shift points were set wrong in the pcm.

HOYS
10-23-2011, 11:56 AM
Could be something sticking in the valve body.

Malaclypse
10-23-2011, 09:15 PM
Sounds like programming first. If it all shifts normally in OD then I'd suspect the tune.