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2019 Tacoma 3.5 hunting between 5th and 6th on 1604, ECT PWR or S mode?

posted by taco_lifer_since_05 in Truck talk, Sep 27, 2025

taco_lifer_since_05OP Long Bed San Antonio, TX 27 posts, joined Sep 2025 #1

2019 TRD Off-Road double cab 4x4, 3.5 with the 6 speed auto, 61k, stock size 265/70R16 Wildpeaks. my fourth Tacoma since a 2005 access cab and the first one with an automatic, so maybe this is on me.

the problem. on 1604 between Bandera road and I-10, the long grades at 65 to 70 with cruise on, the truck will not stay in 6th. it drops to 5th, revs go from 1,900 to 2,600, it climbs the hill, goes back to 6th at the top, and does it again on the next one. on the flat between Seguin and Luling it is fine. with the AC on and two people in it, worse.

what i have tried. the ECT PWR button, which as far as i can tell holds every gear longer and makes it louder, and my mileage went from 19 to 17. putting it in S and pulling it down to S5, which works, but then i am driving a manual with no clutch and forgetting to put it back. turning off cruise and holding the pedal steady, which helps some.

is there a dealer flash for the 2019, or was that only the 2016 and 2017 trucks? and does the 265/75 tire everybody runs make this better or worse? i know the answer is a 4th gen with the turbo but i am not spending 45 grand to fix a hill.

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zr2_shop_wrench Shop Rat New Braunfels, TX 19 posts, joined Sep 2025 #2

indy shop in New Braunfels, we see a lot of these. the reflash you are thinking of was for the 2016 and 2017 trucks, it changed the shift points and the converter lockup logic, and the 2018 and up have that calibration from the factory. so there is nothing to flash on a 2019. the dealer will tell you it is operating as designed and they are right, which is annoying.

what is going on is simple. the 3.5 makes its torque up around 4,600 and 6th is a tall overdrive, so at 1,900 rpm on a grade there is nothing there. the computer sees the load, drops a gear, the truck is fine, it goes back up, the load comes back. the 2019 also unlocks the converter under load before it downshifts, so you get that flare in the rpm before the actual shift.

S5 is the honest answer on 1604. the other thing that helps more than people think is cruise. the cruise on these trucks is aggressive about holding the exact mph, so it downshifts for a 2 mph loss your foot would have let go. no cruise on the hills, cruise on the flat.

on tires, 265/75 makes it worse. taller tire, taller effective gear, it drops out of 6th sooner. a 265/70 on a 16 is where it wants to be, which is what you have.

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cibolo_tacoma Double Cab Cibolo, TX 12 posts, joined Sep 2025 #3

2022 TRD Off-Road, same drivetrain, 27k, i have had it about a week (long story, it will be in the buying board). i drive 1604 to Randolph every morning and yes it does it, less than you describe, but it does it. i have been doing S5 from the I-35 split up past Bulverde road and back to D at the top. it turns into muscle memory after a week. the cruise thing i did not know, trying it tomorrow.

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frontier_pro4x_bee Double Cab Beeville, TX 15 posts, joined Sep 2025 #4

the 9 speed in the 2022 and up Frontier does the same thing between 8th and 9th on 59 north of Beeville with the AC on. a tall overdrive is a tall overdrive no matter who built the box. i have the tow/haul button which locks out 9th and that is my fix. the Tacoma does not have a tow/haul mode as far as i know, which is why you get S5. it is not a Toyota problem, it is a 6 speed with a 3.5 that likes revs problem.

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gladiator_in_kyle Double Cab Kyle, TX 13 posts, joined Sep 2025 #5

the ZF 8 speed in the Gladiator with the 3.6 does not hunt on 1604, but it also has 4.10s in the Rubicon and weighs 5,000 pounds, so pick your problem. mine gets 17 on a good day.

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taco_lifer_since_05OP Long Bed San Antonio, TX 27 posts, joined Sep 2025 #6

update for whoever finds this later. cruise off on the 1604 grades, S5 from Bandera road to the top at Vance Jackson, back to D. two weeks of it and i am not thinking about it anymore. ECT PWR is back to being a button i never push. mileage back to 19.

the wrench is right that this is how the truck was built. the toyota.com spec page for the 2019 lists the 6th gear ratio and the axle ratio if you want to do the math on why 1,900 rpm on a grade is not going to hold. it is not a defect. it is a 3.5 with a tall overdrive in a heavy truck.

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overland_big_bend Access Cab Alpine, TX 9 posts, joined Sep 2025 #7

coming to this late from Alpine. add altitude. same truck, same drivetrain, at 4,500 feet on US-90 west of Marathon the hunting gets worse because the 3.5 is down about 15 percent on power, and the grade out of Marfa toward Paisano pass will have you in 4th at 65 with a bed full of camping stuff. S5 does not save you out here, S4 does. worth knowing before somebody plans a trip on the flatland numbers.

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