5eat transmission problems

I recently replaced my 07 2.5 LGT 5EAT with SI friveTransmission with 05 2.5 LGT 5EAT with SI drive. When I drive a few miles on the freeway I get a check engine light for DTC codes p0700 TCM malfunction and p0735 5th gear incorrect ratio. With the AT TEPM light flashing, cruise control light flashing, and the SI sport light flashing. I've changed the trans filter, fluid, and pulled the pan cleaned and resealed it. Still the same issue. Can anyone help me out?

I am fairly sure but would need others to chime in. The 5EAT has 2 generations that must be paired with the correct year i.e., Generation 1 '05-'06 pair up only with 05 and 06 Legacy's and 07-09 are gen 2 and pair up only with 07-09.

 

I could be wrong but I swear I read that on here a few different times and Im not sure but '04 5EAT's may work as well. Again others will need to chime in but I am fairly sure. I know for sure that its that way with the Valve Body since I just purchased one and did quite a bit of correspondence with the Transmission Specialist. You could try PM'ing Hexmods or send an email to IPT if you cannot get a more definitive answer then I am giving.

Edited April 19, 2019 by Deaus
Added More Information

I recently replaced my 07 2.5 LGT 5EAT with SI friveTransmission with 05 2.5 LGT 5EAT with SI drive. When I drive a few miles on the freeway I get a check engine light for DTC codes p0700 TCM malfunction and p0735 5th gear incorrect ratio. With the AT TEPM light flashing, cruise control light flashing, and the SI sport light flashing. I've changed the trans filter, fluid, and pulled the pan cleaned and resealed it. Still the same issue. Can anyone help me out?

IIRC there are different TCU and trans codes for the 2005-2006 and 2007+ , Someone more knowledgeable than myself might be able to get you details but I remember reading something about it a year or two ago.

 

It would explain your TCU throwing codes

Redundant threads merged.

 

There was no SI drive in 05.

 

The 05-06 auto trans is not interchangeable with the 07-09 auto trans IIRC.

I'd say have a look at both if the ROMs for the 2 card in ECUflash or romraider.

 

 

Check what values for the gear ratios the car is expecting to see in the 05 rom and use those figures in the 08 rom.

 

 

Or just use ECUflash to disable the trouble code p0735 and go from there.

I figured as much, I knew someone on here could clear that up for you. Unfortunately you need a different 5EAT that matches your Generation of 5EAT.

Thanks for your input. I will be checking around. If anyone more knowledgeable comes along please help

Just looking at options, would changing the tcm work or changing the tcm and ecm work?

Pretty sure there are valve body variations. The 05-06 valve bodies could be modified for performance where the 07-09 units could not. That would tell me TCU/ECU swap wouldn't be the only issue but wiring, sensors, etc?

 

This sucks as you found a good used trans to swap in but with all things, one must research first as all manufacturers like to play games. Version this, generation that....you may have to find the right trans. There are plenty of folks in need of 5EAT's so I don't think you would have an issue unloading that one. Good luck, keep us posted.

 

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I still have the other original trans. The torque converter housing is broke and the oil pump isn't working.

I just bought this car in November and I've already had to rebuild the engine because of the Ring land busted and the transmission with busted on Christmas Day those cars been a really bad headache whoever had it before really beat the shit out of it but I couldn't tell that when I was looking at it and it lasted me a month

Damn, I am sorry to hear you going through such a tough time. I bought my 05 GT Wagon in January as well. It is always a risk buying a used car, and these cars specifically seem to be harder and harder to find in good shape and have not been thrashed on by people. What was the mileage like on it? Unfortunately you need another transmission, perhaps you can get your old one rebuilt if it is still in good enough shape? Were you told by a Shop that your new transmission would work with your model year? Perhaps you can go back to them and work something out.

 

Mine has had a few gremlins (i.e., Valve Cover Gaskets, Spark Plugs, few coolant lines ect, ect) pop up but nothing serious so far. I am doing a complete stage 2.5 or 3 in the next month or 2 when the rest of the parts arrive and hopefully it holds up strong.

140,000. I wanted this as my daily driver cuz I Autocross and rallycross my 04 wrx

And this is the 2nd automatic I've ever owned. I hate them. But wanted something different for a change plus the si drive seemed fun

I agree, I personally despise Automatics as well. Occasionally someone else needs to drive my car who cannot drive Manual Transmissions so I had to get an Automatic.

 

My other summer/fun car is unfortunately an automatic as well since they did not make the Monte Carlo SS (L67 3800 Supercharged 4T65E-HD 4speed) but its transmission is bullet proof atleast. When it comes to Automatics the 5EAT is one of the coolest I have tried. It feels alot closer to a Manual in sport mode and has a much tighter feel then my Monte Carlo that has had a bunch of work done to the transmission.

 

Again, sorry you are going through this crap man. What was wrong with the original transmission? Could it be rebuilt or is it too far gone?

Another thing that also is a thing to watch out for is the differential ratio, not sure if it's the same on those model years, but if it's different then you also need to change the rear diff.

 

 

If you only have the code but the gearbox otherwise behaves well, then it's at least a chance that you should be able to disable it or figure out what's missing causing the code. Might be a sensor on the newer MY gearbox that is different or missing on the older.

Yeah I just recently driving it a little through town now it's been going through all the codes one through five so like it was doing it 5th and I reset it. Then it started doing it in 4th reset it then I started doing it and 3rd. Reset it.