OFFICIAL: MY22+ Toyota Tundra - Throttle Lag/Hesitation From Stop Issue(s) - T-SB-0111-22

Okay so going in for the 24TA02 recall results in an update of the TCU calibration to 8A2100C03500?

 

Yes 8A2100C03500 is for 22-23 4WD Tundra's. The recall updates the transmission TCU to the latest revision released. 2WD, Hybrid, and 24's have different cal ID's though.

 

Thanks. I ran my VIN on the recall checker and my 2024 4x4 shows that I have recall 24TA02. Hopefully the new calibration helps.

I don't understand how this throttle delay isn't a safety recall. Is somebody going to have to die because they were trying to make a left in an intersection and couldn't get out of incoming traffic in time because of this delay in order to get resources to fix it?

Coming from an F150 with the 10spd transmission I can confirm this was NOT an issue. I never had anything remotely like this. My truck is 2 weeks old... Not happy to discover this characteristic of the transmission.

 

There is another theory I'm trying to run down, the good thing is that others can gather some data as it only requires a cheap multimeter or battery tester.

I'm wondering if some of the problems are battery related, but it wouldn't necessarily explain the issues with hybrids, but it is possible it could affect the hybrids as well.

Main theory:

The Battery with the Gas model is an EFB (Enhanced Flooded Battery) I note that the battery's overnight resting voltage on my truck is often quite low (11.8 - 12.1V) One thing with EFB's they put out plenty of CCA at 11.8 V easily start the truck, and very quickly recharge. I think that the BMS on the truck probably try's to keep the battery at a max of 80% SOC or something so that the downhill breaking function with the alternator can work.

I do think the truck has some safety measures that shut down things when the battery voltage gets very low around 11.8 V. I do log battery voltage but didn't look at it much. I see many of my past drive's the key on voltage was 11.8V often.

Its also possible the Transmission memory is entirely in KAM (Keep Alive Memory) as noted when they reset my TCM memory they were instructed by TAS to unplug the battery for 30 minutes.

Therefore if the battery charge is low overnight, it could be possible TCM power is cut and the Memory is wiping causing the transmission to need to re-learn where the dead pedal condition most anodically occurs the most.

One of the reasons for my low voltage in the mornings I found was that the Toyota Dash Cam seems to use a lot of juice in parking mode. I also park in a metal pole barn and that results in poor cell data and I'm not sure if that causes extra drain on the battery if the 4G is trying to phone home all night.

The Hybrids have a standard Lead Acid Battery instead of an EFB, however parasitic draw may in some cases cause that battery to be low overnight. The battery just keeps alive system's and starts the main relays for the hybrid system, once that's powered up the DC/DC Converter provides basically charging levels of power to the lead battery.

Its also possible even if you drive your truck frequently but have some parasitic loss because of this battery and the BMS the battery voltage may still plummet overnight.

What I've done so far:

Besides getting the latest TCU calibration via the recall, I have disabled parking mode on the Toyota integrated dash cam and swapped out to an AGM H7 Battery that is higher rated than the EFB. So far resting voltages overnight have remained in the 12.5-12.6V range. It's going to be about 30 days to have meaningful data though. Also note that I have a scantool and after swapping the battery I did preform an integrated current value reset. I don't think this is a super duper important step, but it could help with the start and stop system working properly.

What you can do to test this as a possible factor:

Periodically test your resting voltage before starting the car and see if its in a lower range (below 12.1V). If you have the Toyota dash cam try disabling parking mode and see if the battery voltages overnight are higher. If you have low levels try a trickle charger to maintain a higher voltage overnight.


All this is a theory that needs researching, it may be 100% wrong.

 

Not a car mechanic, IT here.

So you're saying that transmission memory may be getting erased overnight and has to re learn in the morning because battery runs low overnight?

Is there a way to find out in truck strings when transmission learning process was done?

Totally guessing, but it would seem very unlikely that Toyota put in a battery which can't support some very basic transmission learning memory in trucks computer.

I'm doing a ride along with the shop foreman in an hour and can try to ask him, if you have any other specific questions

 

The data for the transmission in tech stream is very limited, have no idea how the learning is done or what values are stored. In my specific scenario the car sometimes sits 5 days without being started, and then the drives are very short, the factory battery always seems to be in a low state of charge, until I disabled parking mode on the camera, then I saw an improvement of resting voltage.

As far as the learning, on the Tacoma's, you go into the utility and select "Reset memory" and it completes in a few seconds and says OK. On the tacoma this sometimes helped with derpy shifts for a while. On the tundra, what happens on this function is it hangs for like a minute, errors out and then the TCM seems to reboot. I have no access to tech info to see if that's the correct procedure or not. I just know what the dealer told me they had to pull the battery to reset the memory.

If you are doing a rid along defiantly ask to have techstream/datalog running and focus on that downshift to 1st as the timing to see the lag.

I'm just wondering if some people that saw the lag also have a low state of charge or not to see if that's a factor.

 

Anyway its probably worth a whole other thread on the charging/battery system a lot of nuisances and weirdness with that system in the name of fuel economy. But mostly just exploring things that would explain why only a small number of people have the issue, seems like if it was purely a software glitch everyone should pretty much have the same glitches.

But there are some other reasons as well such as people may have the lag an not really notice is as much, and a high amount of concerns being blown off at the dealership level to get on the radar due to the hard to replicate/prove.

But also I'm an IT guy, and this has been kind of frustrating to try to reverse engineer it. Seems like a engineer that knows how the software controlling all this works would be really helpful as I could focus on collecting the right data.

 

I think the "low battery" theory is interesting. I only notice it when it is cold out. My poor memory thinks voltage is temperature sensitive so cold could correlate to low.

I don't know if I like this idea over a software bug. The bug could be easier to fix (if they acknowledge it at all).

 

Measured 12.2 on my battery this morning. Truck was off for 12 hours and ambient temp was 40 degrees F. The only thing I've installed with any parasitic draw is the Carista OBD dongle. I do not have a dash cam.

FWIW, I haven't experienced the lag others have. I've even tried to replicate rolling stops etc. and can't seem to make it happen.

 

Sounds good.

People that have the problem will know it right away, trying to pull out and like nothing happens for a good second or two. Post Recall update it seems to be responding properly with a max of 312ms delay. I want to go a full 2 months before I declare the problem fixed.

 

Very interesting. I have the non-hybrid, also the lag, and the truck never goes into idle stop anymore because it's "battery charging." I will test it plus put a charger on it to see if that makes any difference, perhaps replace the battery altogether.

 

Things still seem to be better for me even going out of my way to try to make things happen. Although there is clear indication that are limits imposed until about 850RPM that makes the take off a little jerky. There seems to be always a little initial throttle movement that is cut back, but this seems to do enough to make the pedal not feel dead, but the take off its a little unsmooth.



As far as the battery the only thing anodically is that every time I go to data log the first screen shows the IM Monitors complete status, Previously it was often incomplete or complete one week and then incomplete again the next. Both times so far the IM Monitors have been in Complete state. So in a few weeks if I don't have any issues I'll try to disconnect the battery and see if that's wiping the IM Monitors or not.

 

This morning my battery was at 12.3V and I had to yell GO at it the first stop sign. It doesn't really help, but it makes me feel better. This afternoon when I left work it was 12.6V and it struggled there as well. I have not had the 24TA02 recall done yet. I am an hour away from the dealer and I have not had time yet. I have not notice a difference running in Sport mode instead of standard, but I can tell you do not try tow/haul mode. That sets up a terrible oscillation of delayed throttle overcorrection.

 

Your battery looks great. Do you happen to have a 2022 that might have a really out of date calibration that one is really bad. You could try disconnecting the battery for 30 mins to reset the trans memory, but you do need to go get the new calibration as part of the recall. Regardless what version you are at the recall will update to the latest.

 

Hey, I just did the 24TA02 and it made a big difference. Same as for rlc177 take offs are a bit jerky.

Still huge improvement from the previous trans update I did last year. Fuel efficiency improved a lot to about 11L/100km in a city (yes, I am speechless). This is about 21MPG. Before the update I was around 17MPG average.

Mine is 2022 and things were not bad until last year I did the Trans Update to fix the clunking noise during engine start up. Noise was gone, but the "Gas Pedal Hesitation" at very slow speeds got really bad. To the point I wanted to trade it in for another truck.. (current model is 2022 Platinum, non hybrid)

A bit of clarification, as part of this update they updated both, engine and transmission firmware. I don't have an ODBII port reader so cannot confirm what version I got.


Funny, I also have a battery problem. It is always "charging"... I have 2 battery chargers at home. An old one is capable at charging my Tundra 12V battery to 13.4V. I also have a new charger from NOCO 10A automatic - and it is unable to charge it more than 12.6V... I am puzzled.
Another point - my wife drove a Honda CRV last year and it never had a battery problem. Honda alternator would fully charge the car battery in less then one hour after long vacation trip and would keep it fully charged all the time. Engine start/stop could keep the car off for more than 4 min easilly. In my Tundra the most I ever got with fully charged 12V was 45sec. I am wondering if there is an issue with Tundra battery charger logic....

 

I don't believe getting the "battery charging" message instead of stop start is actually a low battery condition, but it seems more like a generic message that its judging the battery, however if the engine stops and then restarts for battery charging like 2 seconds that could be more of a low state of charge. I have the access to the scan data its so complicated how it works. I do think their logic does leave people with very specific short daytime drive cycles at a lower state of charge constantly. Most of the constant charging happens when the headlights are on, it forces it to do constant voltage charge.

As far as your charger if you are on the terminals of the battery instead clamp the negative after the current sensor so it understands that current is going into the battery not sure if that's a thing or not while its off, but when ever having a maintainer while the key is on always insert the power after the current sensor.

 

Mine is a June 2022. If had the hesitation so I had them update to the December calibration. That fixed the clunk at startup/shutdown, but it didn't do anything for the hesitation. Need an oil change too, so I should make an appointment.

 

Just to clarify, unplugging the battery for 30 minutes WILL reset the transmission memory and it will start the re-learn process from scratch?

 

I'm not 100% sure due to not having the access to the tech docs, but I have done the battery pull a few times, it will wipe out emissions monitors temporarily and wipe out the clock on the radio otherwise its harmless to do. I note that after that the trans shifts a little weird and there is a higher likely hood for more delay for the first few drive cycles.

 

how's it going with the new flash, any lags?

I havent had time to get mine done yet

 

As far as "lags" there is still lag, but as far as instances of pressing the pedal and no response for a significant time I have not had any of those events but its not something I can cause to happen on demand before. (I.E. The T bone issue)

Consistent Lag (annoying) instead of random lag (raging) is the best I could describe it.

If I go a month or so without a problem then I think its probably fixed.

 

ya, thats what I was referring to, the dead pedal issue. the small amount of regular turbo lag etc, is fine, I don't have much of a problem with that, they spool fast and the trans is great.

I have had the dead pedal here and there, so thats why would be nice if its gone now

 

Same here. I was trying to drive mine frequently over the last couple of days and did get a few very minor hesitations that are not nearly as bad as before the recent Trans Update.

Question about the battery. I was thinking of buying an AGM as well, but I am reading posts about voltage in AGM needing a 14.6V to get fully charged. Is Tundra capable of producing this voltage to keep AGM fully charged?

 

I'm doing a long term AGM test, the typical charging voltage is 14.1 volts. When it gets into the mode where it decides to charge more when costing downhill it does get higher.


Some data from drives with the AGM





Older drive data with the EFB

 

That needs an explanation! If I understand correctly, the car produces higher voltage from Alternator with flooded batteries.

My other question is - what happens when I tow an RV with 200Ah of 12V lithium in there connected with 7 pin. Lithium has a higher SOC compared to my Tundra's EFB. Is it possible that Tundra can draw some current from the RV instead of charging it?

 

I wasn't logging all the data from the battery, the current does matter as well as what mode the charging system in as far as what the voltages will be.

The EFB might have a higher voltage because less amps are going into the battery but I don't have the data.

There are differences in the way the 2 types of batteries work but I think they are largely compatible as the AGM meets or exceeds the spec.

The trailer might have a current diode to prevent current from flowing from the trailer to the cars system but I have no idea exactly.

 

Anyway not to derail this thread with much talk about batteries except there is a possibility for very low voltages (Resting voltages below 11.8V) possibly causing unintended TCM memory resets. There was an older thread about AGM Batteries you could probably ping about your situation.

 

I tried disconnecting the battery for one hour few months back. When I connected it back, the clock was off by 20 min and later adjusted by itself. BUT, I did not feel anything different with transmission behavior! This week when I got the update for Trans + memory flash the transmission fealt VERY clunky for the first drive. Then it started getting smoother with every next drive. I felt nothing similar with battery disconnect. It was no different from any other drive.

I later found an article online (google) that newer cars require dealer Trans reset in order to flush the memory. Simple battery disconnect does not work anymore.

I am sure there must be an option with ADBII plugin and a phone app to get it done at home...

 

rlc177,

I think you might be on to something on the voltage issue. I have never experienced any throttle lag or dead pedal. My typical cold start has me transiting about a 1/4 mile at low speed until a stop. I have started at temperatures down to the high teens. I have never measured the load on the battery with ignition off, but I don’t have a dash cam and don’t subscribe to connected services.

Can you explain the alternator engine braking? When decelerating, I notice something akin to light braking which I have tried to correlate to a downshift on a Scangauge 3, but that doesn’t seem to be the case.

 

You will know if you are in this mode when in ECO, NORMAL, or CONFORT modes and while under acceleration the battery meter on the dash will seem kind of low (Basically where its at with the engine off) Its actually about 12.8V, then under coast or breaking the voltage will shoot up to as high as 15.1V. It does this to save fuel.

If its in Sport, Tow/Haul, or the headlights are on it should be in constant voltage mode. If the system detects that the battery is low, it will also stay out of the mode and stay in constant power mode (Refresh Charge mode)