I bought a used Rav4 2003 with 140k km's (87k miles on it).

Transmission shifts well.

Should I be concerned about possible future transmission ECU failure and go to Toyota (under warranty?) before the issue develops or is it safe to ignore it until the problem comes up?


Thank you

I would wait for the problem to happen. There is no panic since you has enough time to fix the ECU when it occurs. By the way there is no warranty left.

 

Thanks. Should I just get another ECU from the junkyard and fix it (change those faulty resistors) to keep as a backup?

 

I have 2003 RAV4 2.0L with 140,000 km on its clock. I took my car to a local mechanic to have the car scanned
and no code popped up. And no warning light comes up on my dashboard. Does it mean my ECU is fine at this point? I am wondering whether cracking solder issue can be detected by scanning the ECU ????? If it could, I would like to have my car scanned by local mechanic on a regular base to predict the ECU fault. Does it work???

 

No. I've done much more research since my initial post here. I was wrong.

It can be an ECU issue is if you notice your car has trouble shifting and/or idling.
A check engine light or code will not necessarily come up.

Do not rely on mechanics to solve this issue for you. This is an electronics design fault which is in many cases undetectable, even by transmission specialists.
Even if a code does come up on the scanner related to the symptoms above, it will be the wrong code anyways.

For example if you think your car has difficulty accelerating or getting up to speed, or has rough shifting, or has idling issues. Then you should probably get the SMD resistors on your ECU re-soldered.

In fact this is exactly what happened with my rav4 2003 (with 140k also when I bought it). The car had difficulty accelerating and getting up to speed. Something didn't feel right since I purchased it.

I managed to find someone who sold repaired ECUs here for $300. So now I have an ECU and my old one as a backup which I will be taking to an electronics specialist to resolder the SMD resistors.

After I swapped the ECU the car could accelerate and shift far better and the idling had improved as well. Before I swapped it no check engine light or codes ever came on. So again scanning for codes at the local mechanic is meaningless for this issue. Scanning a faulty computer will give you faulty results.

I recommend you find someone who sells repaired ECU, or use one of the ECU repair services available online, or find an experienced electronics repair specialist near you that can re-solder the SMD resistors.

But if you think your car does not have these symptoms above, leave it the way it is for now.


One more point about codes. If the check engine light doesn't come on, you likely don't have any codes to worry about so there is no need to scan for codes. If check engine light does come on and you have some of the "predictable codes" relative to this issue AND you've noticed the symptoms above, then it's at that point you must take action on the ECU. I went by the feels and acted on the ECU before things got worse and before any check engine light came on.

 

Hi Everyone,

I do those ECU repairs. In those RAV4 the problem is not a simple resistance. The problem here is Cold solder joint, it often results in cracks in soldered joint over the period. This will prevent current to flow easily. Can't fix this with a simple soldering iron, need to solder at the right temp. with the right tools.

Would like the service, please contact me.
toyotarav4repair@gmail.com