[Xtremluck]

Hoping some others have run into this before. I have a 2012 SR5 with about 96,000 miles. I'm currently having problems with 4WD engagement. When I move the lever into 4H nothing happens. The only way I can get it to engage is if I put it in reverse and then back into drive. 4WD is used quite frequently, probably at least 100-200 miles a month.

Any thoughts?

[WallyT4R]

Are you sitting still when you try to engage it? Try and engage it while moving forward at a slow speed.

[Xtremluck]

Originally Posted by WallyT4R

Are you sitting still when you try to engage it? Try and engage it while moving forward at a slow speed.

It has the same engagement problem standing still, crawling, moving at a slow pace and moving at a medium pace

[wfo9]

Originally Posted by Xtremluck

Hoping some others have run into this before. I have a 2012 SR5 with about 96,000 miles. I'm currently having problems with 4WD engagement. When I move the lever into 4H nothing happens. The only way I can get it to engage is if I put it in reverse and then back into drive. 4WD is used quite frequently, probably at least 100-200 miles a month.

Any thoughts?

Please explain how you are engaging it. Typically you need to be moving... The splines in the ADD need to align and this can't always happen while sitting still.

If you are still having issues while moving forward.. it is most likely the ADD actuator going bad. Not that difficult to replace it.

[Xtremluck]

Originally Posted by wfo9

Please explain how you are engaging it. Typically you need to be moving... The splines in the ADD need to align and this can't always happen while sitting still.

If you are still having issues while moving forward.. it is most likely the ADD actuator going bad. Not that difficult to replace it.

Driving 5-10 mph and pulling the lever into 4H is usually the most common scenario. I can drive for literally miles and it will not engage. I then stop, put it in reverse and then put it in drive again and boom engagement! This problem came up recently, had two years of problem free engagement before that.

I was thinking bad actuator as well, the transfer case was submerged in water about a couple of months ago during a water crossing. Wonder if that may have something to do with it.

[(none)]

Originally Posted by Xtremluck

Driving 5-10 mph and pulling the lever into 4H is usually the most common scenario. I can drive for literally miles and it will not engage. I then stop, put it in reverse and then put it in drive again and boom engagement! This problem came up recently, had two years of problem free engagement before that.

I was thinking bad actuator as well, the transfer case was submerged in water about a couple of months ago during a water crossing. Wonder if that may have something to do with it.

Missing a bit of critical info here.
A- does the light on the instrument cluster come on, flashing, then just never stop flashing until you do your reverse maneuver?

B- Are you going straight the entire time?

Try again in a gravel parking lot or your yard. Turn the knob, the 4wd indicator light should now be blinking. Turn the steering wheel 3/4 or so either direction, go forward and as you are, turn the wheel back to center then the other direction. See if that helps. If the 4wd indicator light doesn't come on right away, just stop and realize the problem is probably in the knob.

[Xtremluck]

Originally Posted by (none)

Missing a bit of critical info here.
A- does the light on the instrument cluster come on, flashing, then just never stop flashing until you do your reverse maneuver?

B- Are you going straight the entire time?

Try again in a gravel parking lot or your yard. Turn the knob, the 4wd indicator light should now be blinking. Turn the steering wheel 3/4 or so either direction, go forward and as you are, turn the wheel back to center then the other direction. See if that helps. If the 4wd indicator light doesn't come on right away, just stop and realize the problem is probably in the knob.

Sorry, that was an important detail! No light at all. The the 2010-2013 SR5 models have a mechanical lever so no dial.

[(none)]

Originally Posted by Xtremluck

Sorry, that was an important detail! No light at all. The the 2010-2013 SR5 models have a mechanical lever so no dial.

Cool, now we are getting somewhere. So, to double check. You move the lever from 2H to 4H, no light comes on? The lever moves freely? What about going from 4H to 4L? Obviously while stopped. Still no 4wd light? How about the 4Lo light now?

There is a switch on the transfer case that senses when the lever is in 4H. That signals the light and the ADD to connect. I'd say that switch is bad or gummed up. You can defiantly tell if you shift it into 4Lo and only the 4Lo light comes on. IIRC, the 4LO and 4Hi swiches are the same, so you can swap them and see if the problem changes.

[3wbdriver]

Originally Posted by Xtremluck

I was thinking bad actuator as well, the transfer case was submerged in water about a couple of months ago during a water crossing. Wonder if that may have something to do with it.

If as I understand you have a stick, the transfer case is engaging the front axle. What is NOT engaging is the actuator (ADD) on the front axle that slides a splined sleeve over the axle stub so the front end is fully engaged. This is what Toyota uses in lieu of locking hubs to reduce wear on the front axle. This is the actuator wfo9 is referencing. I'm willing to bet if you moved the lever from 4hi to 4lo you would still get the slight gear growl indicating the transfer case is shifting into low.

Using reverse to get it to engage is kind of confusing. If mine won't engage at low speed I usually just roll forward while moving the steering from left to right and back to get the splines to line up with the sleeve. I can actually hear the sleeve click into place when it happens. The front actuator is an electric motor and worm gear drive that moves the fork in the axle. And the motors have been known to corrode over time, especially if immersed on any kind of regular basis. I agree with wfo9's assessment from the description so far.

[Xtremluck]

Originally Posted by (none)

Cool, now we are getting somewhere. So, to double check. You move the lever from 2H to 4H, no light comes on? The lever moves freely? What about going from 4H to 4L? Obviously while stopped. Still no 4wd light? How about the 4Lo light now?

There is a switch on the transfer case that senses when the lever is in 4H. That signals the light and the ADD to connect. I'd say that switch is bad or gummed up. You can defiantly tell if you shift it into 4Lo and only the 4Lo light comes on. IIRC, the 4LO and 4Hi swiches are the same, so you can swap them and see if the problem changes.

Yup, 4H -> 4L also doesn't produce the 4WD light.

[Xtremluck]

Originally Posted by 3wbdriver

If as I understand you have a stick, the transfer case is engaging the front axle. What is NOT engaging is the actuator (ADD) on the front axle that slides a splined sleeve over the axle stub so the front end is fully engaged. This is what Toyota uses in lieu of locking hubs to reduce wear on the front axle. This is the actuator wfo9 is referencing. I'm willing to bet if you moved the lever from 4hi to 4lo you would still get the slight gear growl indicating the transfer case is shifting into low.

Using reverse to get it to engage is kind of confusing. If mine won't engage at low speed I usually just roll forward while moving the steering from left to right and back to get the splines to line up with the sleeve. I can actually hear the sleeve click into place when it happens. The front actuator is an electric motor and worm gear drive that moves the fork in the axle. And the motors have been known to corrode over time, especially if immersed on any kind of regular basis. I agree with wfo9's assessment from the description so far.

Let me try your side to side trick. Never thought of that!

Thanks for all the great info guys!

[wfo9]

Originally Posted by Xtremluck

Yup, 4H -> 4L also doesn't produce the 4WD light.

If the light does not come on and you have a manual t-case... It is the 4wd switch at the top of the transfer case. I would not normally think going in to reverse would help that, but it must be loose or something.. the twist of of the t-case reversing must be making the connection.

It can be replaced without removing the T-case, people here have done it.. but it is not super easy to reach up in there. It has to be done by feel.

The turning back and fourth.. can help with the ADD, but not that switch. The switch is what tells the ECU to engage the ADD.... There is also a 4Lo switch, so make sure you change out the 4H one.

I can find the diagram of it if you need it.

[YJIANG]

I know it's a wild shot - but this is what happened to me: I changed my tires and the shop mistakenly put on different sized rear tires - a 275 and a 265. The small difference in spinning speed turns the diff ever so slightly on a straight line that produced the exact same problem you described. Took me several months to figure out.

[FrontRange4Runner]

Originally Posted by wfo9

If the light does not come on and you have a manual t-case... It is the 4wd switch at the top of the transfer case. I would not normally think going in to reverse would help that, but it must be loose or something.. the twist of of the t-case reversing must be making the connection.

I think this is the best place to start IMHO. If you are not getting a light, then the vehicle is not sensing your intentions to engage 4wd. If it realizes you want 4wd and it can't engage for some reason, the light will come on and flash. This has happened to me a bunch, but I have never had a no light situation.

[wfo9]

This is the switch... on the passenger side somewhere near that center rib. Should be pretty easy to feel. Might just try messing with the connector to see if that resolves it.