Delayed shifting when cold, yes I know its normal but.....

[LittleCaesar]

There is no dedicated tranny ECU, it is built into the main one I believe.

Can't see it being the valve body but a flush with a quality ATF fluid like Castrol IMV may help.

 

[thegipper]

The Mystik brand fluid that is sold at fleet farm is supposed to be pretty good fluid. Plus, I've used that same fluid for well over a year in my 4R and it has always shifted perfectly without any issues. I also used the fluid in my Jeep for 5+ years without any issues. I don't think it's the fluid, plus, why would it only give me trouble on cold starts then act completely normal afterwards? And why would it all of a sudden start happening now when that same fluid has been used for awhile?

I am starting to seriously think it is something with the ECU like Antlered suggested. This morning before work, I fired it up and let it warm up in my driveway for a good 10 minutes before I left. Engine temp was 166 degree's before I left.

It shifted PERFECTLY??? Didn't get stuck in 1st and drove 100% normal as usual. Tranny temp (via Glowshift gauge) did not even register yet like normal (<80 degrees) since it was just sitting in park and not even moving.

I am seriously thinking it has something to do with the ECU at this point to some degree. The coolant temp sensor seems to be working fine since my readings on my ultra gauge seem consistent, reliable and realistic. Maybe the TPS? I know the ECU takes readings from the TPS to tell the transmission things but again, no CEL so no way to know if the TPS is actually acting up or not. The other possibility is some kind of partial blockage in the valve body that is keeping the fluid from passing through correctly until the fluid thins out a bit.

The good news from the test that I did this morning is I highly doubt the tranny itself is bad based on the totality of the circumstances and tests performed thus far. No metal in the pan (in fact, it was too clean), fluid is brand new looking, no burnt smell, no slipping, no harsh shifting, no shutter, no noises, no delay in shifting from P to D or R and so on.

How weird hey?

 

[thegipper]

There is a junkyard about 10 minutes from my house which usually has a few 3rd gen 4runners in it at any given time. I could try swapping the ECU and see if it fixes it.

I should note again that I am getting a random pending P0301 every few days that never shows up on my dash, just on my ultra gauge. Engine runs like its brand new, no issues at all. Maybe the ECU has a few issues going on?

If I do try that, is there a certain year or trim level that I need to grab an ECU from? Mine is a 97 SR5 V6 4WD.

 

[thegipper]

I did some quick research on the ECU problem Antlered suggest about 2nd gen Rav4s. The symptoms of it not shifting sound very similar to mine.

At this point, I think swapping the ECU may be the next thing I do. The junkyard is pretty cool and I bet they will let me return it if it doesn't fix the problem.

I have also searched extensively on T4R and found no other reported cases of this so I may be the first (if it is the ECU). My luck is amazing....

 

[AntleredRuin]

I did some quick research on the ECU problem Antlered suggest about 2nd gen Rav4s. The symptoms of it not shifting sound very similar to mine.

At this point, I think swapping the ECU may be the next thing I do. The junkyard is pretty cool and I bet they will let me return it if it doesn't fix the problem.

I have also searched extensively on T4R and found no other reported cases of this so I may be the first (if it is the ECU). My luck is amazing....

Well the silver lining with being the 'first' is that a junkyard part should suit you just fine. Very low odds that the donor will have a bad ECU as well.
I had the same issue with my FPS. I think I found a case where only 1 other went bad, so I got an eBay used one for $30 shipped, vs around $200 new. Nearly 40k ago.

Yeah, I say ECU. I THINK that the ECU is the same across the board for model years, even 2wd and 4wd.
If it is the ECU, and a junkyard one fixes it, for shits and grins, try baking your bad one in your oven on 375 for about 7 minutes. Should reflow the solder and 'fix' the issue. Of course, you'd want a backup one first, just in case.


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[thegipper]

I checked the yard by me and they have a 97 v6 4wd ECM for 50 bucks. I think I'll stop by after work on Friday and pick it up.

Is the ECM just plug and play? Undo the connector remove ECM and install the new one?

Obviously disconnect the battery first? Anything else?

 

[AntleredRuin]

I checked the yard by me and they have a 97 v6 4wd ECM for 50 bucks. I think I'll stop by after work on Friday and pick it up.

Is the ECM just plug and play? Undo the connector remove ECM and install the new one?

Obviously disconnect the battery first? Anything else?

Speaking purely from the Rav4, all I had to do was disconnect the battery, then replace the ECU. It definitely did drive a little wonky at first also as it relearned fuel mapping and shift points, etc. I actually got a 'rebuilt' one from eBay for around $100 as this was a common problem, and I would not trust a junkyard Rav4 ECU. The seller had a basic list for 'breaking it in'.
Start it up and let warm up fully, then drive around in a place where you can do a lot of starts and stops, but using your basic driving style. Don't baby it or floor it, etc. Then drive on the freeway if possible, etc.
Of course, to test if it actually worked, I had to let it completely cool down again after the 'breaking it in' period.

 

[thegipper]

Anyone know how to remove the ECM on these trucks? I've read that it is behind the glove box. Do you simply remove the glove box and there it is? Or do I have to tear the dash apart?

Thanks

 

[88toy4x4]

I believe it is not your ECU. I had the same problem and some others have too. The problem is with the printed(flexible) circuit that is on the back of your instrument cluster. Those can fail after some time and you can choose either to replace it($$$) or try to fix it. I was able to trace and find a break in one of the circuits on mine. After fixing that, I didn't have shifting issues anymore(wouldn't shift out of first, felt like it was in neutral, reverse indicator lit when in park, etc). I would give this a shot to see if you can locate a break somewhere.

Here is a thread - Transmission Issue???? - that shows the printed circuit on the back of the cluster - scroll for pics.

And in this thread - 2000 4Runner SES: P1780 - you can read in post #14 where christo_27 fixed his where it was broken.

Hope this helps.:bounce:

 

[AntleredRuin]

I believe it is not your ECU. I had the same problem and some others have too. The problem is with the printed(flexible) circuit that is on the back of your instrument cluster. Those can fail after some time and you can choose either to replace it($$$) or try to fix it. I was able to trace and find a break in on of the circuits on mine. After fixing that, I didn't have shifting issues anymore(wouldn't shift out of first, felt like it was in neutral, reverse indicator lit when in park, etc). I would give this a shot to see if you can locate a break somewhere.

Here is a thread - Transmission Issue???? - that shows the printed circuit on the back of the cluster - scroll for pics.

And in this thread - 2000 4Runner SES: P1780 - you can read in post #14 where christo_27 fixed his where it was broken.

Hope this helps.:bounce:

TheGipper, seeing as how your junkyard find is the same year as yours, I wonder if you should grab the cluster board as well, as per the post above. If the return policy at that place is good, it never hurts.

 

[JayRolla]

Usually when an ECU is failing its the CAPs. Open up the case of the ECU and inspect the board for leaking caps. If they are failing you can replace them pretty easily with a soldering iron and some practice.

 

[AntleredRuin]

Usually when an ECU is failing its the CAPs. Open up the case of the ECU and inspect the board for leaking caps. If they are failing you can replace them pretty easily with a soldering iron and some practice.

I think in the case of the Rav4, it's the resistors, but capacitors make sense too. (at least in my mind). As the vehicle runs, the caps fully charge, vs leaking (or bulging) and empty from a cold start.

 

[thegipper]

I believe it is not your ECU. I had the same problem and some others have too. The problem is with the printed(flexible) circuit that is on the back of your instrument cluster. Those can fail after some time and you can choose either to replace it($$$) or try to fix it. I was able to trace and find a break in one of the circuits on mine. After fixing that, I didn't have shifting issues anymore(wouldn't shift out of first, felt like it was in neutral, reverse indicator lit when in park, etc). I would give this a shot to see if you can locate a break somewhere.

Here is a thread - Transmission Issue???? - that shows the printed circuit on the back of the cluster - scroll for pics.

And in this thread - 2000 4Runner SES: P1780 - you can read in post #14 where christo_27 fixed his where it was broken.

Hope this helps.:bounce:

Thank you for the information!

Would your truck also shift out of first fine once the truck warmed up or was the problem always there no matter what?

 

[thegipper]

I read both threads and while informative, I don't think that circuit board is the cause of my issues. I am not having any of the symptoms in either post. My headlights/brights doesn't change the issue. I have no CELs on. I am also having no issues with the reverse light indicators or any of the other dash lights.

I am not saying it can't be the issue but given what my symptoms are, I think the ECU is more likely at this point.

Thanks again for the information though.

Jayrolla, I have fixed capacitors on TV boards before so I am familiar with soldering etc. I think I'll just swap the entire ECM just to be on the safe side. If it does fix it, I'll take my ECM apart and check the capacitors and everything else to see if I can pinpoint the problem.

 

[thegipper]

I was mistaken, my junkyard I use doesn't let you return any electrical parts so it would be a $50 gamble.

Maybe I'll take my ECM apart and see if anything obviously looks bad (capacitors etc).

Or maybe I'll just buy the ECM from the yard and if it doesn't fix it, I'll have a spare if someone needs one on here.

 

[thegipper]

Ok so I took the ECM out and inspected it. I don't see anything wrong with it that I can tell visually. The connectors are all clean and I cannot find any corrosion anywhere.

When I started it to leave work today, I got the P0301 pending code again, seems to be happening more. Engine is running perfect and no CEL lights on the dash, the pending code only shows up on my ultra gauge.

Here are a couple photos of the ECM board.

Still totally lost. Could be the ECM, could be something else. Hmm

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[thegipper]

I should add that my 4R is not my primary vehicle so I'm in no rush.

Hopefully we can figure this out, thanks for the help so far.

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[88toy4x4]

Thank you for the information!

Would your truck also shift out of first fine once the truck warmed up or was the problem always there no matter what?

Once my truck warmed up, it drove fine.

I read both threads and while informative, I don't think that circuit board is the cause of my issues. I am not having any of the symptoms in either post. My headlights/brights doesn't change the issue. I have no CELs on. I am also having no issues with the reverse light indicators or any of the other dash lights.

I am not saying it can't be the issue but given what my symptoms are, I think the ECU is more likely at this point.

Thanks again for the information though.
~snip~

Also, for what it's worth, I didn't have any of the other symptoms either other than the the reverse light would be dimly lit even though it was in park. And even then, that didn't happen all the time. No CEL either.

 

[thegipper]

Once my truck warmed up, it drove fine.



Also, for what it's worth, I didn't have any of the other symptoms either other than the the reverse light would be dimly lit even though it was in park. And even then, that didn't happen all the time. No CEL either.

Sounds like I need to check that circuit board on the cluster than.

How hard is it to tell if there are any breaks in the solder? Or did you just swap in a new one? Also, my 97 doesn't have any indicators on the dash for what gear you are in, I'm assuming this is where you said the reverse light would be faintly on sometimes even though you were in park?

 

[LittleCaesar]

Usually you would have to look underneath the board for bad, old solder connections. The caps look fine, though for all the LCDs and plasmas I have repaired I have seen leaking caps work for years with no real ill side effects. Look with a magnifying glass for breaks as well as rust around joints.

I wish someone could get their hands on a circuit diagram of the ECU.

If you have $50 to burn, you can chalk it up as a learning experience.