4Lo Behavior, Is this normal?

I bought a new 2023 Tacoma Off-Road (auto transmission) last night. I took if for its first brief drive on a dirt road this morning, and noticed 3 surprising noises when using 4Lo that have me worried.

1. The first time I shifted from 4Hi to 4Lo I came to a complete stop and, in a fairly fluid motion I shifted into neutral, push-turned the dial from 4Hi to 4Lo, shifted into drive and lifted my foot off the brake... resulting in a loud-gear grinding noise from the transfer case. I immediately braked and jerked the shifter back into neutral ending the noise. I got to thinking that the Taco must need a pause after turning the dial to 4Lo (waiting for the 4Lo light) and then shifting to drive. I have a 2019 4runner that I use 4wd in regularly, so I am at least somewhat familiar with Toyota 4wd systems. I think my error was not pausing for the electronic transfer case actuator in the Taco since I'm used to the instant, manually-shifted transfer case in the 4runner. I wonder how much damage that brief gear-grinding did? It was so stinking loud. Subsequent 4Hi->4Lo attempts (of which there were many) were silent after I added a pause before shifting from neutral back to drive.

2. One of my 4Hi to 4Lo shifts went just fine, but a few seconds later and after about 50 feet of movement I went around a turn and heard a loud clunk. At the same time, I lurched forward as though I was just rear-ended. This clunk must have been accompanied by a sizable energy release in some part of the vehicle. What could cause such a clunk? I see some mention of this on the forum. I've never experienced anything but buttery smoothness from the 4wd system in my 4runner, so I'm unsure of what is normal for the Taco.

3. When accelerating from a stop in 4Lo the shifts of the transmission are not subtle at all, every time, no matter how gentle my gas-pedal foot. The 1st -> 2nd and 2nd -> 3rd shifts of my auto-transmission have me checking my rearview mirror to see if someone just bumped me. This is like a lurching or bucking behavior. Again, I never felt anything like that in my 4runner. Is this normal Taco behavior?

Other than these issues, the Tacoma seems great. I don't notice the transmission gear-hunting problem that others complain of, and coming from other pickup-trucks I don't mind a truck being a little 'trucky'. I'm not expecting a refined luxury sedan feel. I just want to know if I've got some transfer case or transmission issues that need attention. I've got those new-owner jitters that have me wondering if I got an unlucky bad-one. For those wondering, I did check all of this out during pavement test-drives (before purchasing) and I did not experience these issues. Admittedly my checks of the 4wd system were very brief since, as a rule, I try not to use 4wd on pavement.

 

Don't do turns on dry pavement in 4x4

 

1. Stay stopped and in neutral until the 4LO lights are on and you’ll be good as you found.

2. 4LO is a lot of torque and the dirt road you were on was likely not slippery enough to let the wheels fully slip free when needed. You turned and the wheels kept traction until they jerked free resulting in the clunk and jerk feel.

3. Shifts in 4LO have always been a bit rougher than in 2/4hi in my Tacomas.

 

1-As stated already, you must stay stopped and in neutral until the shift is completed. You will hear 2-3 clicks from the transfer case and the pre-collision and trac lights will come on as well as 4LO. Then you can place the truck in gear and drive on. Keep in mind, you will have a lot of torque in 1st gear so keep your foot firmly on the brake when you place the truck in drive.

2-Are you positive your truck was in 4LO when you started the turn? Did it shift while turning? Many different scenarios could cause this.

3-The shifts are definitely pronounced when you are using a torque multiplier. I found that using the manual shift mode is smoother on the neck when using 4LO

All that said, your truck is operating completely normal.

 

You should read the manual. Every vehicles 4WD system works differently and an electronically actuated one like in the Tacoma is going to be different than the 4R.

https://assets.sia.toyota.com/publi...Z*MTY5MDM4ODA4NC4xLjEuMTY5MDM4ODExNy4yNy4wLjA.

Page 303.

As mentioned, you should come to a complete stop before switching to 4LO and then remain in neutral until the 4LO light is no longer flashing before shifting back to drive.

The shifts are pretty normal and a tune helped for me. YMMV.

 

Yeah, you need to come to a full stop for being able to engage 4lo. Only thing I noticed once in 4lo is a siren like whine if running at full throttle. Truck will engage, and disengage from 4lo slicker than goose poop on a wet lawn.

 

operator errors

 

1. Yeah, you definitely want to make sure it is fully shifted (light no longer flashing) before going. I'd imagine you didn't do much damage, but not something you want to make a habit of.

2. Remember, the turn radius on these trucks is much larger than that of the 4Runner. You likely turned too sharp with too much grip when you were used to being able to turn tighter in the 4Runner.

3. Yes, these trucks all shift a bit rough just due to the way they're geared and programmed. Personally, I haven't noticed issues like what you've described while in 4Lo, but then again, I'm also likely not shifting higher than 2nd when in 4Lo as I need slower and more controlled speeds, or else I'd probably just use 4Hi.

 

if the light is still flashing that mean it's not engaged. don't move forward until it's engaged or it will damage the gears.

the clunk could be drivetrain binding due to the turn.

my shifting was not smooth at all in 4lo either. the more you use it, the smoother it gets. just the nature of this "learning" transmission. my s-mode shifts were pretty harsh too when i first started using it. especially the downshifts.

 

When I first test drove a 2021 I took it to a empty parking lot, did some turns and backed into some spots to check
the mirrors and 'view' out of the windows etc.

Slipped to 4Hi and started driving a bit making turns etc ( pavement mind you ).
Tried to use 4Lo but had no clue of the procedure - light just blinked nothing seemed to happen.
Sales-dude was clueless.... told me the constant blink was normal...

I've since learned the procedure and have used both on sandy-dirt-roads for exercise etc.

Points from above - complete stop, ( i then count to 3 ), then while in neutral switch to 4Lo - wait for blinking to stop - count to 3 - then go.
Same reverse procedure as well...

Although it is stated you can slip to 4Hi while traveling a reasonable speeds I never do it - I take it to a complete stop first.
The only time I broke my rule was when I ran into some deep mud and thought damn I ain't got time to stop I gotta GTF outta here.
I was only doing like 20 at the time so it didn't bother me - I was lucky to get out of that crap too -

 

My tundra shifted rough when engaging, or disengaging 4wd, Not a lick of roughness on this tacoma, except for watching the green 4wd dash led, you'd never know if in or out of 4wd. I think there's definitely some differences how these transfer cases are manufactured/put together.

 

OP here... so I'm hearing that the gear-grinding during my first shift to 4Lo was operator error. Crossing my fingers that no damage was done. The other issues I mentioned sound like they may be normal behavior. When I off-road in my 4runner in the US desert Southwest and the terrain gets rough/steep/sandy I often run in 4Lo, even if it is several miles of that. I have never heard any odd noises or had bucking auto-transmission shifts doing that. I like the control that 4Lo offers under those conditions, and I don't mind taking it slow. Is that approach going to work with the Taco? If I'm going to experience binding/bucking/clucks etc. through normal use of 4Lo I want to be sure that I'm not doing damage to the truck.

 

All I can remember with how rough any of the 4wd functions were when engaging, or disengaging on my tundra that it never got any worse. It use to shake the truck when using the 4wd button before 4wd actually engaged, and even sometimes it took a number of seconds for it to work. Seemed everything ran very smooth once the transaction was done....4hi, or 2wd.

 

I was more referring to shifting between gears in general. My bad for not clarifying

 

Shifting into, and out of low range can be tricky with any 4X4. I've owned or driven quite a few over the last 50 years. You are changing the transmission gear ratios by a factor of around 2.5:1 to as much as 4:1 depending on the exact vehicle. Tacoma's are closer to 2.5:1. That's quite a big difference and getting the gears to mesh can be difficult.

If you're at a dead stop and if the gears aren't lined up it won't make the shift until they are. That requires a partial rotation of the wheels to get the gears aligned. I find it best to come to a NEAR complete stop, shift the transmission to neutral then move the selector to low range while the wheels are at a VERY slow speed. 1-3 mph is where you want to be. If you try to shift from a dead stop the actual shift won't take place until you start to move, and it may shift with a bang or loud clunk when that happens.

As to the hard shifts. With the extremely low gearing combined with higher-than-normal rpm's that is normal. But if I'm in low range I only use 1st gear or reverse. If you put the transmission into "D" and drive in low range as soon as it goes to 2nd gear you have pretty close to the same overall gear ratio as 1st gear in high range. That kinda defeats the whole point of having low range. If you're going to be in low range 2nd gear just leave it in high range 1st gear.