4x4 slow to engage on incline. Why?

I’ve found myself in a few situations where I’m pulling off a highway onto a forest service or gravel road that quickly turns upwards. When I go to engage 4x4 and the vehicle is pitched going up it takes a good while of the light blinking as I’m driving along before it actually engages. Not the end of the world and I usually can plan ahead and switch into 4x4 on level ground which kicks in almost immediately. It is a little annoying tho and more so can anyone here explain the reason why this happens?

 

My gravel driveway is on an incline, probably around 30 degrees at some parts. Mine has been doing this since Ive owned it, and my last 3rd gen did it as well.

 

What I have noticed is that it won't let the 4x4 kick in until you let go of the gas. But, when you're going uphill, you rarely let go of that gas. I would try (if you want to experiment) punching the gas a bit to get uphill momentum, then let go of the gas and watch the light. I betcha that will let it kick into gear. Curious if it's something else tho!

 

Sounds like it’s under to much load and is protecting itself

 

I’ve heard it from a handful of Tacoma owners but I’m not sure if that’s a normal trait of 4x4 systems in general, something Toyota’s 4x4 system does or just a Taco thing

 

The Tacoma's are just like this in my experience, the lockers behave the same way. Shift/lock before you need it is the best way to play this.

 

Both my old 3rd Gen and my current 2nd Gen do this. I think it has something to do with transfer case timing the shift into 4WD but I could be mistaken. Totally a normal Taco quirk.

 

Thanks for the tip I’ll try that out

 

Haven’t owned to many 4x4’s, just a H3 with the V8 that was always in 4hi and wife has a 4Runner. Im getting the impression this is just a Tacoma thing

 

Can you shift it into 4X4 with the transmission in neutral, foot on the brake and then place it into drive?

 

I have to engage 4lo. Also have zero issues with 4hi when I’m on level ground. It just takes a few extra seconds if I have to engage 4hi on an incline. I was just wondering if someone knew the mechanical explanation for why Tacoma’s do this

 

I've experience this too while on an incline. It's been new for me as I'm use to pulling a lever on a Jeep.

 

Yes, even the owners manual identifies it as something you might observe. Like other dude said, same with engaging your locker.

Not sure how H3's work with regard to full time AWD or 4WD, but the Tacoma uses a selectable 4WD system using open diffs that is a bit different than a full-time 4WD system. What this means is the wheels all rotate at the same speed and you generally don't want to use your 4WD system on dry pavement. It'll cause your diffs and driveline to "bind up" and can cause damage.

FYI - here's the owners manual for other info. Lots of good info in there.

https://www.toyota.com/owners/resources/warranty-owners-manuals

 

Very helpful. Thanks for that info

 

It’s a a load thing (it doesn’t want to engage 4x4 under a load). It’s really a Toyota thing, not just Tacomas. A lot of other vehicles are like that too though. In my old ‘86 Toyota pickup and ‘95 4Runner, I had to roll backwards for 5-20 ft. to get them to go out of 4x4. It’s always best to engage the 4x4 before you need it, but the good thing is, if you get yourself stuck and the wheels are spinning, 4x4 will engage in this situation (same with the rear locker for those that have them).

 

Nice. That makes sense and is good to know. Appreciate the tips

 

Even in a manual shifted transfer case its rare to have a 100% smooth shift into 4L. Usually you grab the handle and shove it in and expect a slight gear on gear clash. The actuator on the electronically shifted cases dont have the luxury of forcing the lever. I imagine its just sitting there at the gate timing a perfect entry. I've noticed with my 5speed, if I depress the clutch and or engage a slight motion forward or reverse, that the shift into 4L is aided. Its like the gears for 4L are not perfectly aligned until i give it that slight inch of motion to sync up the gears.

 

It is normal and by design. My 2017 F-150 does it,,, just did it today. Hell our Polaris Ranger down at the farm does it too.
You want to engage 4wd before you need it

 

It's a load thing.
It's not going to shift under load - flip the switch, let off on the skinny pedal for a bit, and it'll engage.
Same for disengaging 4WD.
It's been like this on all of my Toyotas.

 

Let off gas and it will shift. Gears don't like to synchronize when under load. Let of gas for a half second. It will pop right in.