PLEASE Help Its the Transmission Again

daluvabull · #1 10-11-2009, 07:02 AM

Just replaced my 3rd transmission in 5 yrs- ugh
1st Cottman rebuild
2nd Local shop reuild
3rd used 4.44 with rear diff and shift mod

Currently shifts are irratic. Does not seem that it shifts down to lower gears until it warms up- resulting in a blinking power light. At times it shifts good. Other times it seems to stay in 3rd. If manual is selected, it most usually shifts ok. The power light does not luminate at start up or when the ignition is on. Consequently, an error code cannot be identified. The mileage is 182.5K. It has an externl cooler and filter. All warning lights illuminate under hard acceleration while attempting to shift down from 3rd to force a shift to 4th on the freeway. Additionally, all warning lights fade on and off occassionally. The car will roll while in drive with the engine off.

Bad install, connection or TCU? If TCU, any ideas on availability and cost of a used one? Where is the TCU located. A search of the How-To documents was not fruitful.

Of course any insight or suggestions that can be offered are greatly appreciated.

Peace,

Jeff

Trevor · #2 10-11-2009, 03:39 PM

Greetings Jeff,

"All warning lights illuminate under hard acceleration while attempting to shift down from 3rd to force a shift to 4th on the freeway. Additionally, all warning lights fade on and off occasionally."

This could indicate an alternator rectifier problem with A.C. being imposed on line. However it is difficult to tie this in with Hard acceleration. Alternating current could possibly be playing havoc with the TCU, but this has not been previously reported as a problem.

Exactly which warning lights illuminate? Could any wiring have been upset during the transmission installation? Is the filter a common denominator, in respect of your several transmission failures?

Cheers, you need them.

Trevor.

daluvabull · #3 10-11-2009, 06:28 PM

Thanks for the reply. I believe only the red lights illuminate. I think I have chosen shops that could not work on the SVX properly. Wiring errors are quite possible after the last install. Again, in hindsight, I am not confident of the previous shops work. It has been difficult, and expensive, trying to correct the transmission problems. If I could be directed to where literature is to illustrate the wiring paths and units that could be influencing the operation of the transmission, it wold be most appreciative.

Again, thanks

Jeff

huck369 · #4 10-11-2009, 11:32 PM

We had a member at the last Dragon Meet experience similar issues, and it turned out that his crank pulley was separating....not enough voltage getting to the TCU to control shifts.

I am assuming you have a set of matching tires on it, and keep them rotated....as unmatched tires will eat the 4EAT, and an external tranny cooler........and if you're on your third tranny, either you have another issue, or you just abuse them, if it's the latter, then the old saying " You gotta pay, to play" comes into mind.

daluvabull · #5 10-12-2009, 04:54 AM

The crank pulley was replaced in 2004. I drive conservatively-really. It seems difficult finding a dependable shop around Houston, other than the dealer, that can work on the SVX. Could a faulty alternator cause an electric drain that would result in errorneous TCU signals. The alternator has not been replaced- that I know of. What puzzles me is why I do not get a power light on start up. I am not able to extract codes from the TCU.

Thanks for the information. PLEASE keep it coming.

Jeff

huck369 · #6 10-12-2009, 05:08 AM

Most places will check you alternator for free, definitely worth checking out..

You still didn't say if you have matching tires on your car, you sound like someone who would, but it is important information when talking about bad trannys...

Trevor · #7 10-12-2009, 05:19 AM

Quote:

Originally Posted by daluvabull

The crank pulley was replaced in 2004. I drive conservatively-really. It seems difficult finding a dependable shop around Houston, other than the dealer, that can work on the SVX. Could a faulty alternator cause an electric drain that would result in errorneous TCU signals. The alternator has not been replaced- that I know of. What puzzles me is why I do not get a power light on start up. I am not able to extract codes from the TCU.

Thanks for the information. PLEASE keep it coming.

Jeff

It is not a matter of "an electric drain," or low voltage. A faulty rectifier within the alternator will result in alternating current being imposed on the normally 12/13 volt, Direct Current system. Often this fault is not picked up by auto electricians doing a test. Make sure anyone testing knows their job and explain that you suspect a rectifier fault.

It is not possible to make certain diagnosis from afar, but the alternator is a likely cause. The previous post mentioning a failing pulley could also have resulted in a "dirty" output from the alternator. Two of us pointing to the alternator is not by accident.