'04 SR5 erratic brake performance

[t-man]

If this is intentional design why does it not happen all the time?
EG: When traveling on interstate @ 70mph, barely tapped and immediately released brake pedal as I approached construction site, speed limit 60mph. This flat section of road which I drive often and have driven in many different vehicles is well known to me and my actions in this truck were same as always except when I touched & released brake I was gently forced forward against the seatbelt and truck slowed strongly. With no traffic behind I let it coast, within 100yds +/- speed was down to 45mph and still dropping when I slapped the gas to get back up to speed before I got run over.
Other times along this same stretch, in this truck, I've performed the same actions and had perfect reaction, no "strong" slowing but retaining same speed as when I release brake, then gently slowing to 60+/- by the time I reach the site and only need minimal gas to simply maintain speed.
Seems like it should do one or the other of these behaviors consistently, no?

How hard are you hitting the brakes? If you hit them hard enough it has brake assist that kicks in and stops you, fast! Lol
I just replaced a wheel bearing. Dirt and crap was on the abs sensor and sometimes it would over act on braking, or when the cruise control was on the speed gauge would suddenly go up and down freaking the cruise control computer out.
It's pretty hard to diagnose something without being there as people have different thoughts of something not being right. Everything sounds normal to me, just user not used to the advanced system in the Toyota's, but it's just to hard to tell. Have you taken it in to a mechanic? This is the once in a million time I'd recommend a Toyota mechanic hoping they know the system and will understand. Good luck.

 

[Fred Ritchie]

Took my mechanic for a fairly long ride while he monitored his analysis computer (he spent 8 years as Toyota service tech before opening his own shop), no codes. I dropped truck with him today for him to drive for next couple of days to see if he can decide whats up. Will pick it up on Thurs. and decide how to proceed.

Thanks for all the input.

 

[Fred Ritchie]

Just an update for anyone interested. Got my truck back from mechanic today. After using it as his for three days he agrees something is wrong with tranny but doesn't have idea of exactly what, basically, "you shouldn't have to use the accelerator to go DOWN a hill, no matter what vehicle is involved".

Went to talk to dealer and all they could do was make appt. for me for next week, will take ride with me and see if they get idea. I am not encouraged.

 

[t-man]

op2:

 

[Greydog]

Check all the calipers for frozen Piston or corroded pad slider pins?

When I have felt something like this, calipers were the cause.

 

[Fred Ritchie]

Appreciate the input but the first thing I did when purchased was replace old rotors and pads, breaking is great. I have had the calipers and pistons checked and all works fine.
Definitely a tranny problem. After three days of driving the truck my mechanic can make problem occur on demand, given proper road conditions (small hill requiring minimal braking at top to avoid freewheeling on the down hill side). When downshift occurs, on hill of about 30 degree angle, truck will hold this lower gear all the way to bottom,dropping to 30mph or lower if you let it. However, mechanic discovered that if, when the downshift holds too long, he moves shift lever sideways (as though you were going to shift gears manually) and just move it back to 4D the problem disappears and the truck "freewheels" just like all other vehicles I, or he, have ever encountered.
This is absolutely a trans. problem, undetectable by computer analysis either by my man, a second mechanic or the dealer (inspected before I bought vehicle) so far.
Have appt. with my local dealer for Monday, tech will take drive with me and give his opinion. I explained that I may not be able to force problem to show itself on demand but told them that my mechanic referred me to them and asked if they called him he would explain what he has found and exactly how to make problem occur and dissappear, mechanic to mechanic so no confusion is caused. Of course the dealer says they don't need to talk to him, they'll go for ride with me and MAYBE then call him if needed.
Worthless, but the only remaining option before listing truck for sale.

 

[t-man]

Appreciate the input but the first thing I did when purchased was replace old rotors and pads, breaking is great. I have had the calipers and pistons checked and all works fine.
Definitely a tranny problem. After three days of driving the truck my mechanic can make problem occur on demand, given proper road conditions (small hill requiring minimal braking at top to avoid freewheeling on the down hill side). When downshift occurs, on hill of about 30 degree angle, truck will hold this lower gear all the way to bottom,dropping to 30mph or lower if you let it. However, mechanic discovered that if, when the downshift holds too long, he moves shift lever sideways (as though you were going to shift gears manually) and just move it back to 4D the problem disappears and the truck "freewheels" just like all other vehicles I, or he, have ever encountered.
This is absolutely a trans. problem, undetectable by computer analysis either by my man, a second mechanic or the dealer (inspected before I bought vehicle) so far.
Have appt. with my local dealer for Monday, tech will take drive with me and give his opinion. I explained that I may not be able to force problem to show itself on demand but told them that my mechanic referred me to them and asked if they called him he would explain what he has found and exactly how to make problem occur and dissappear, mechanic to mechanic so no confusion is caused. Of course the dealer says they don't need to talk to him, they'll go for ride with me and MAYBE then call him if needed.
Worthless, but the only remaining option before listing truck for sale.

Lmfao! COMPLETELY NORMAL AND EXPECTED BEHAVIOR! As we've been telling you, they all do this. It's the computer holding the gear to slow you on hills, as it's supposed too. If you change gears manually it will overide the computer. Mine doesn't like to change into overdrive on any sort of incline because of my 35" tires and stock gearing, but if I shift into 4th and immediately back into Overdrive it will shift every time and it's all good.

 

[Fred Ritchie]

Acknowledge your insistence however, it is not normal to have to accelerate to get a vehicle to descend a hill of such an angle. My Mazda 3, which weighs maybe half as much as the truck on this same hill will free wheel to 65 or above if you do not use brakes to hold speed down (speed limit is 45) whereas the truck, driven at same speed down same hill, with single light tap once on the brake at top of hill will decelerate to 30 and below if you don't actively accelerate it downhill.
I have presented your position to all mechs. and techs who have tried to troubleshoot and ALL agree, "this is not a normal design" and if it is it needs to be remedied. It slows the vehicle so much, after coming off brake pedal which extinguishes brake lights, that I am in real danger of getting rear ended in traffic since I continue to slow when all other traffic comes off brakes and starts to accelerate while I continue too slow.
I have heard your input several times but it makes no sense, after driving more than 40 years I have never heard of such a design and all trained pros who have inspected agree this is problem. If yours is doing this maybe you
have just learned to accept it but you are only input who insists its right.
Further, if your opinion is right why does the truck shift up by just moving shift handle left and back into 4D? If its coordinating gear selection based on its ability to "perceive?" what is needed why will it then freewheel well beyond speed limit unless you touch brake again.
I since your irritation that I don 't take your input as final but it does not provide any logical explanation for such behavior. If it is design, it actually causes a dangerous situation which is unacceptable regardless of your position on this.
Sorry if I'm a bit direct but we have covered this point before and it is not supported by Toyota techs. mechanics or any driver's experience I'm aware of unless of course we are talking ab out a manual trans., which we are not.

 

[t-man]

Acknowledge your insistence however, it is not normal to have to accelerate to get a vehicle to descend a hill of such an angle. My Mazda 3, which weighs maybe half as much as the truck on this same hill will free wheel to 65 or above if you do not use brakes to hold speed down (speed limit is 45) whereas the truck, driven at same speed down same hill, with single light tap once on the brake at top of hill will decelerate to 30 and below if you don't actively accelerate it downhill.
I have presented your position to all mechs. and techs who have tried to troubleshoot and ALL agree, "this is not a normal design" and if it is it needs to be remedied. It slows the vehicle so much, after coming off brake pedal which extinguishes brake lights, that I am in real danger of getting rear ended in traffic since I continue to slow when all other traffic comes off brakes and starts to accelerate while I continue too slow.
I have heard your input several times but it makes no sense, after driving more than 40 years I have never heard of such a design and all trained pros who have inspected agree this is problem. If yours is doing this maybe you
have just learned to accept it but you are only input who insists its right.
Further, if your opinion is right why does the truck shift up by just moving shift handle left and back into 4D? If its coordinating gear selection based on its ability to "perceive?" what is needed why will it then freewheel well beyond speed limit unless you touch brake again.
I since your irritation that I don 't take your input as final but it does not provide any logical explanation for such behavior. If it is design, it actually causes a dangerous situation which is unacceptable regardless of your position on this.
Sorry if I'm a bit direct but we have covered this point before and it is not supported by Toyota techs. mechanics or any driver's experience I'm aware of unless of course we are talking ab out a manual trans., which we are not.

My Mazda CX-9 does the exact same thing as my 4Runner, but much smoother with its 6 speed Trans.
It's cool man, I respect your thought process here. Maybe I'm wrong, who knows, but there have been many discussions about our trucks holding gears up and down hills.
I'll take a video today since I live on a pretty good sized hill. See if it compares to yours.

 

[Fred Ritchie]

Input please?
Took truck into Toyota yesterday & went for ride with tech. Couldn't make truck behave erratically and no codes but the tech offered an explanation. According to him, these trucks are designed to "learn" a person's driving habits and then "predict" what action you will want the truck to perform (ie: braking force level, shift points, etc.). Have to admit, this makes no sense to me but he said he would wipe the computer and then I would have to drive it at least 20 miles so it could acquaint itself with my driving habits. Drove over thirty miles home and noticed a couple of "hard downshifts" as before but possibly not as extreme.
Also, this passed weekend, for the first time, the truck pulled away from a stop sign in what felt like second or third gear. Approaching stop sign truck had demonstrated the same hard downshift that I have been complaining about. Luckily no traffic was approaching since it took at least three times as long to get up to safe speed for major two lane. A real danger!

First: does this make sense to anyone? If so, what happens when my wife needs to drive vehicle, will it predict actions for me since I drive it 90% of time?

If this is intended design then this is not vehicle for me. I insist my vehicle do what I want it to do when I tell it to do so. And what about trying to pull away in the wrong gear?

"Confusinger and confusinger!!!"

 

[t-man]

Sounds like he told you the same thing everyone else has told you.
FYI, Chevy's are made so they go into basically a limp coasting mode. Many older ford's too. Toyota doesn't.
I think you've reached the end of your line here. Nobody else is chiming in, don't think they will cause you really aren't listening because you aren't hearing what you want to hear. Nothing is wrong with your Toyota, trade it in for a chevy so someone else can enjoy one of the most reliable vehicles on the road. Sorry to be blunt, but it's the honest truth.

 

[Fred Ritchie]

Must be nice to be so certain from so far away. Does this explain why truck has now started, occasionally, setting off in 2nd or 3rd gear? If its working so perfectly why does it not go back to its selected 3rd gear if I move shifter to left and back to right on the downhill coast? If it is correctly compensating for my inability to drive wouldn't it just go back to 3rd, not move into 4th and stay there allowing the truck to freewheel as every other vehicle on the road?
Seems like it should behave one way or the other every time. But I'm sure you have answer for this too, no?
No forum is of any use if its response is to simply tell people they don't know what they're talking about when they describe their own experience. I am neither delusional nor idiotic and you are not omnipotent.
'Nuff said all around.

 

[t-man]

I like these.

 

[Fred Ritchie]

Not sure what your pics are supposed to mean but I give up, I'll say what your ego so desperately needs to hear, "you're right"! I don't know what I'm experiencing, neither of the two mechanics who have experienced the same behavior know what they're doing but both agree it is not right and referred me to the dealer. Even the tech at the dealer agreed it wasn't performing as intended, also said this is one of most common problems people have with 4 Runners and all he could do was wipe computer, I then drive minimum of 20mi to let it "learn" my new driving habits. If problem persists then its a matter of starting to change components and hope we get it.
Maybe you could talk to Toyota directly and tell them to stop fixing what ain't broke, tell them this is perfectly normal 'cause obviously they're as dumb as I am.
Feel better now?