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Discussion Starter · #1 ·
Hi Everyone
I own a 2001 RAV4 Model-ACA21W, 1AZ-FSE engine, U140F Trans Axle. Lately, I started having issues with it shifting gears. Hard shift from 2nd gear to 3rd gear and also jerking when shifted from Park to Reverse or from Drive to Reverse. I have read alot already on this forum which points to a bad ECU. I did check the Transmission fluid and had it replaced with a new fluid. Checked the Shift solenoids and they are all within the reccomended resistances.
I am waiting to get a refurbished ECU. In the meantime, one of my mates gave me a Manual Transmission ECU.
I was wondering, if anyone on this forum has ever tried using one on an Auto Transmission? And what could I end up damaging if I use one on my RAV4?
Thank you
 

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If you're lucky it just won't work at all. If not so lucky it will finish off your automatic.
 
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Agree with Dr. Dyno. Opposite situation - bought a new manual shift CR-V some years ago and while it was being check driven by the dealer it was discovered that the ECU was bad. Service department thought of replacing it with one from an automatic shift vehicle on their lot but after checking with Honda corporate they were told that doing so would not work and could even cause other problems.
 

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Hi Everyone
I own a 2001 RAV4 Model-ACA21W, 1AZ-FSE engine, U140F Trans Axle . . . In the meantime, one of my mates gave me a Manual Transmission ECU.
0.01% chance of that working. For better or worse, later model RAVs have multiple Control Units for system management. The RAV4.2 has but a single ECU. As the part numbers for the ECUs are distinguishable among auto and manual transmissions, I would have little to no expectation that the manual (ECU) would have the software to run the U140F. I wouldn't be surprised if it couldn't even start the engine.

I would be patient and wait for that refurbished unit (y)
 

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Discussion Starter · #5 ·
Thanks everyone for your responses.

Just letting you all know, I have tested the Manual Transmission ECU on my Auto Trans RAV4 and it does work. Took it for a drive around. No hard shifting or Jerking on Reverse. However, while driving, it does not feel as though its shifting gears. Seems like it is running on one gear only.
I did open up both the AT ECU and MT ECU and to my surprise, they both are similar. They both have the same circuit board part number. Everything is similar to both.
I am confused as to why they are similar since one ia for Manual and the other is for Auto. They should be different.

And I am so tempted to start using it now..

Any ideas..
 

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No hard shifting or Jerking on Reverse. However, while driving, it does not feel as though its shifting gears. Seems like it is running on one gear only.

And I am so tempted to start using it now..

Any ideas..
There's your answer no hard shifting because there is no shifting. If you're okay with that then drive it.
 

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If all of the electronic components are identical, it would seem that the only variable would be how the ECU is flashed.
 
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. . . I have tested the Manual Transmission ECU on my Auto Trans RAV4 and it does work . . . However, while driving, it does not feel as though it's shifting gears. Seems like it is running on one gear only.
It wouldn't be the first time I'm proven wrong, but I'll appeal to your intelligence and ask if it's not shifting gears, does it in fact work? I am surprised it started though :oops:

I did open up both the AT ECU and MT ECU and to my surprise, they both are similar. They both have the same circuit board part number. Everything is similar to both.
I would actually expect this, what you're looking at is the serial # from the parts supplier. Toyota would later program these in house. If you plugged an OBDII reader into this you probably wouldn't find any data related to the U140F. But, you've proven me wrong once today already :LOL:

If all of the electronic components are identical, it would seem that the only variable would be how the ECU is flashed.
Exactly. Wash, rinse, repeat.
 

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Discussion Starter · #10 ·
It wouldn't be the first time I'm proven wrong, but I'll appeal to your intelligence and ask if it's not shifting gears, does it in fact work? I am surprised it started though :oops:
Yes, it started and ran just like it was running off its own ECU. Where I live, I have to drive up two steep hills and it did that without any problem.
As I have mentioned earlier, as I was driving, I could not feel or hear it shifting between gears. But I could stop, idle and then take off and speed up without any hard shifting.
 

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Discussion Starter · #11 ·
There's your answer no hard shifting because there is no shifting. If you're okay with that then drive it.
I am only concerned that driving it with the MT ECU might end up damaging the transmission etc, therefore, I was hoping someone on the forum would know exactly what could go wrong.
 

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I was hoping someone on the forum would know exactly what could go wrong.
Apparently no one else has the guts to try it.. Your RAV4 is the guinea pig.
 

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Yes, that is exactly what could be the only difference.
The tach would reveal whether the transmission is shifting. About the ECU, I seem to recall that other owners on this forum have had their ECUs flashed for some reasons, so it might be possible to have yours flashed with what is needed for it to convert it to auto transmission use.
 

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Discussion Starter · #15 ·
Thank you everyone for your responses, thoughts and ideas.
Since no one here has tried this before and had any experience of this, I will try it out, and as Dr Dyno mentioned, mine will be the guinea pig..:ROFLMAO:.
I will give it a run for a few days while waiting for the refurbished ECU. Hopefully, the transmission does not get damaged:oops:
 

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Discussion Starter · #16 ·
Hi everyone
So I got the refurbished ECU. However, on the cover of the ECU it says - 1AZ FSE, CVT..the original one for my RAV4 is 1AZ FSE, 4X4 AT..
I was wondering if anyone knows if this refurbished ECU will work on my car?

Thank you
 

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From that designation and the one you had on the previous ECU it appears that they sent you one for a CVT transmission,if there is that sort of transmission available where you are.
 

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Discussion Starter · #19 ·
From that designation and the one you had on the previous ECU it appears that they sent you one for a CVT transmission,if there is that sort of transmission available where you are.
Yes, they sent me the wrong type of ECU.
Any possibility that it might work on this AT?
Anyone know?
 

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Yes, they sent me the wrong type of ECU.
Any possibility that it might work on this AT?
Anyone know?
Since an AT is completely different than a CVT I'd say the chances are ZERO. But then I thought the same about the MT ECU, so your poor RAV4 is the guinea pig again. I just hope it doesn't suffer too much.
 
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