Overdrive issue. Tstat, shift solenoid, trans temp sensor????

[phattyduck]

I went back and watched the video again...

After you finish accelerating to 70 and start to cruise, the RPMs drop to ~2400 (4th, torque converter unlocked), then drop right after that to ~2100 (4th, torque converter locked).

It looks like your truck is hunting between 3rd and 4th/OD, but each time the RPMs drop (back into 4th/OD), you can see the torque converter lock.

It does sound like it could be a control issue (ECU)... Though I still like to think of those problems as rare. Any chance the truck sat unused for long periods of time? That can cause capacitors to go bad...

-Charlie

 

[Tampa_T4R]

I went back and watched the video again...

After you finish accelerating to 70 and start to cruise, the RPMs drop to ~2400 (4th, torque converter unlocked), then drop right after that to ~2100 (4th, torque converter locked).

It looks like your truck is hunting between 3rd and 4th/OD, but each time the RPMs drop (back into 4th/OD), you can see the torque converter lock.

It does sound like it could be a control issue (ECU)... Though I still like to think of those problems as rare. Any chance the truck sat unused for long periods of time? That can cause capacitors to go bad...

-Charlie

Regarding the bold above...Actually, yes. He has had it sitting for about 5 months. He would start it every once it a while to keep the battery charged, but he has only put 26k miles on it the last 6 years.

Well, at least that's good the TC is locking correctly.
It was mentioned that 96-98 models do not throw a code for by transmission temperature sensors, correct? Maybe that's my issue, the ECU thinks that the trans is too cold for OD engagement? Does it work like that?

Edit: You're right, I just watched the video again too and it does have the extra little drop once it goes into OD/4, good catch!

 

[thegipper]

ECU can certainly go bad but it is somewhat rare.

A couple years ago I was getting a random pending misfire code even though the engine was running perfectly fine. While I was trying to diagnose a different issue with my transmission, I swapped in a different ECU I got from a junk yard. While it didn't fix my transmission issue, the code has never came back.

 

[Down by the Water]

Hey,
I'm the guy in the post referenced above. The ECU was bad. Replacing it with a used one fixed the shifting issue. A used one should run you around $85. Swapping it out is easy (though I had a shop do it, long story.) It never threw any codes related to this problem.

 

[Tampa_T4R]

Well, looks like my trans fluid is actually fine after all. Blue shop towel had me thinking it was grey -_-

Took a 20 mile drive home today at 70 MPH... Overdrive worked perfectly the whole way. Has to be ECU acting up.

 

[Tampa_T4R]

Trans fluid, the dark parts are from the top of the stick

 

[phattyduck]

That fluid does need a change, but it probably isn't an emergency. It should look cherry red with no hints of brown when it is good shape.

I actually drove the 4Runner this morning and checks - those are the exact RPMs/speeds for what I described above (4th locked, 3rd, 4 unlocked, 4 locked).

I have a '97 4WD ecu in the garage, but I'm not sure if it is compatible with a '96...

-Charlie

 

[Tampa_T4R]

That fluid does need a change, but it probably isn't an emergency. It should look cherry red with no hints of brown when it is good shape.

I actually drove the 4Runner this morning and checks - those are the exact RPMs/speeds for what I described above (4th locked, 3rd, 4 unlocked, 4 locked).

I have a '97 4WD ecu in the garage, but I'm not sure if it is compatible with a '96...

-Charlie

NICE.

Yeah, I plan on doing a trans flush with new filter eventually. I'll probably just start with a drain and fill for now. The main thing is it looks like I don't have a huge issue there and no strawberry milkshake is a plus

I'll do some research on the ECU and see if it will work.

Thanks again Charlie

EDIT: oh, also it once again did not have the overdrive issue this morning driving 20 miles to work. I hit 80 at one point and it stayed in OD. I didn't know 3rd gens have magical healing powers?

 

[Tampa_T4R]

She’s fixed! Turns out it was in fact the ECU! No more p0505 code and no more overdrive issue! Thanks for all your help fellas! Hopefully this helps someone down the road!