2020 Tacoma off-road won’t shift from 4th please help

Can you 'see' both atf temperature sensors on your scan tool?

 

Although not really what you are describing, there is a transmission TSB that people seem to love. Given that would be an easy thing for the dealer to do maybe worth trying to see if ECU software update would give you any relief.

https://www.tacomaworld.com/threads/tsb-0092-20-is-awesome.696230/

 

@Bulletproofmafia, I am taking a 90 mile highway trip to Denver on Tuesday and will pay attention to speed VS RPM’s and how it’s holding gears using CC as well. I did have the T-SB-0092-20 done and it did help the “hunting” issue. I have roughly the same setup as you. Toytec Boss lift, 285/70R17 (a bit different size) E-rated heavy Nitto Trail Grapplers, and a full set of armor at 300 lbs. Will post results on Wednesday morning.

 

Help me out a bit, how is it completely obvious that his engine/truck is defective? Any what exactly is “broken”? Please be specific.

 

End of thread, OP there's nothing wrong with your truck. Larger tires, lift and faster speeds will create more resistance which will keep the transmission out of the overdrive gears. Cruise control is not designed to give you better gas mileage, only to keep the truck at selected speed no matter the condition.

If you're going to continue to drive at 80mph with larger tires then expect to see poor mileage and a higher revving engine at those speed.

 

I agree with this. It sucks for OP to realize this after purchase, but the third gens do not play well at the speeds he is trying to drive, even stock. The lift and tires have just made it worse. There is nothing for the dealer to fix, because there is nothing “wrong”. (Except maybe the design of the drivetrain, but thats outside of the dealers wheelhouse)

 

Based on the tire size calculator when your speedo says 80mph you are actually doing 88.5mph.

 

Sorry, tough pill to swallow, but all that aftermarket stuff is not going to be warrantied by Toyota. The dealer that installed should be,,,, but clearly they're not. You may have to get it repaired on your dime. I'd definitely check axle gear ratios, if the computer was calibrated for any gear chances and tire sizing. Also borrow some stock tires/wheels and go for a test drive, I'm sure there some localyocal that'll help you out.

 

I’m afraid the simplest answer here may be correct. Pre-ovtune, mine would hop out of 6th with a good crosswind or slight incline with a stock vehicle. I’m guessing that OPs added lift and tires put the strain just over the threshold for 5th and it jumps to 4th. Really sux for OP if his daily use involves regular highway time.

Would the dealership be willing to slap some stock wheels on it for a highway test? If that puts you regularly in 5th, then.... dunno what to say.

The recommendation to confirm transmission fluid is a great one though. The taco has been known to come low on fluid.

 

Anything over 65 in both my 1st and 3rd gen trucks kills MPGs, at 75 you can almost see the gas gauge dropping.

When I first got my 3rd gen I went up to 265/70/17 and would average 21mpgs on my daily 20 commute as long as I kept the speeds 65 and below, no problems holding 6th. If I ran it over 75 it would toggle between 5th and 6th so I would just keep it in S5, mpgs took a big hit.

When I went up to 285/70/17 load C tires, my daily commute at 65mph is 18mpgs. It will now toggle between 5th and 6th at 70mph.

It's the price you pay buying a truck with two OD gears and then deciding to put bigger tires on it.

 

To be clear, I was referring more to the dealership. You can say whatever you’d like but nobody can pretend that a truck driving like that is tolerable. If the dealer put the stuff on, they should have an idea as to how it’s going to run and expect backlash if it runs like shit. Also I mentioned people trying to use the OV tune as a workaround literally every time Toyota refuses to fix something that should be fixed.

 

$58,000

 

I was looking to see if anyone had pointed that out. I was trying to figure out how it was running 5300 RPMS in 4th. At 80 mph, I’m at like 2000 RPMS in 6th and 2500 in 5th. Not sure what 4th is, but I know it doesn’t jump all the way to 5000+ RPMS.

It does seem odd that it would hold 3rd gear like that. Even towing, 4th is all I ever really need. Cruise control does some weird stuff though, so maybe that’s it.

 

Absolutely. Only real fix is for the OP to regear on his own dime. It's not Toyota's fault that the dealer modded it and the OP bought it. What I would suggest is to find some normal standard rims and tires and put those on. If it shifts OK then it's simply due to the larger tires.

That engine just doesn't have enough oomph down low in the RPM range to stay there running down the road with that tire size.

 

The dealer isn’t going to re-gear your truck, if you think it needs to be done, that’s on you to pay for.

We’ve all seen posts about who buys modded trucks from dealerships for astronomical prices and apparently this is the type. You got the truck you wanted, now it’s yours. Warranty is on the truck and defective suspension components, not making it drive like a stock height truck with stock sized tires. Gears are available, break out the wallet if you’re paying a shop.

 

This right here.

You're driving a taco .... At 80+mph and youre in here bitching about mpgs .... Come on man, you weren't born yesterday. If you want to drive 80+mph regularly, get a Supra.

Trucks aren't designed for high speeds. You also have a lift and bigger tires.

If you're gonna keep complaining, get OVTune, and regear to 5.29.

And maybe everyone else in here bitching about it can do almost 3 min of reading anywhere on the internet to figure out that driving 80+ mph destroys fuel economy no matter what vehicle you're in.

 

5:29's and it's a beaut.

 

You're right. 86 mph with 34" tires would be turning 3323 rpm in 4th, 4952 rpm in 3rd.

 

I'd swap on factory size tires and see how it goes. Far easier than a regear.

 

Check your speed with your phone or another source, as several have said you’re going faster than your speedometer indicates with the larger tires. You’re smoking everything on the highway in your video!