Whats wrong with my 4x4! (searched everywhere, please help)

[zerge916]

Ok, the issue I am having I cannot seem to find anywhere on this forum or anywhere else for that matter.

So our 4x4 on 4th gens is supposed to actuate on the fly up to 50-60mph(not sure exactly doesn't matter for my issue because I usually try to turn it on at 10-25 mph.).

When I try to turn my dial to 4hi, I get a strange whirring/grinding noise and I can't tell where it is coming from. The other weird thing is it sometimes starts to pull to the right when this happens. The whole time the 4x4 light is flashing. BUT, if I stop and drive forward and backward a few times (3-5) it goes right in and even switches into 4lo no problem(not while driving of course). Does anyone have any idea on what the issue could be??? I searched everywhere.

Also a few things to add not sure if it will help.
it is a 2007 limited
bought it not too long ago so not sure when diff fluids changed
it has a ripped cv boot on passenger side.
thanks

 

[techno]

Well, two things happen when you engage 4Hi. A small motor on the transfer case moves little gears into place that make a connection between the TC and the front drive shaft. Secondly, a system called ADD (Auto Diff Disconnect) works to connect the front passenger side axle to the front differential and hence complete the front drivetrain system.
So, the whirring sound will likely be coming from the TC actuator or the ADD actuator. The pulling to the right suggests the ADD is not working properly and causing resistance to that axle, therefor pulling you in that direction. I would troubleshoot the ADD system first.

 

[zerge916]

This is something I haven't looked into. I think this is most likely my issue. Thanks!

 

[techno]

These might help with the ADD system.

http://4runnerclub.com/i/4r_files/f...toyrm/07toypdf/07rmsour/4runnerr/03300810.pdf
http://4runnerclub.com/i/4r_files/f...07toyrm/07toypdf/07rmsour/4runnerr/033004.pdf

 

[wc11]

50-60 mph sounds awfully high to be engaging 4WD.
I've never done it at that speed. It's usually when I first start up or below 30 mph.

But when doing so, I let off the accelerator, turn the switch, wait a second and then accelerate. It then lock in.

 

[Trumpet]

50-60 mph sounds awfully high to be engaging 4WD.
I've never done it at that speed. It's usually when I first start up or below 30 mph.

But when doing so, I let off the accelerator, turn the switch, wait a second and then accelerate. It then lock in.

Toyota spec's 2wd to 4Hi at up to 62 MPH, for 4Lo you must stop and be in neutral.

Their spec.

 

[techno]

50-60 mph sounds awfully high to be engaging 4WD.
I've never done it at that speed. ....

I find it particularly useful when I'm running from the police and choose to bust through some fences and across farmers fields...

 

[Rodtheviking]

I find it particularly useful when I'm running from the police and choose to bust through some fences and across farmers fields...

Take out as many mail boxes as you can.

 

[zerge916]

Well, two things happen when you engage 4Hi. A small motor on the transfer case moves little gears into place that make a connection between the TC and the front drive shaft. Secondly, a system called ADD (Auto Diff Disconnect) works to connect the front passenger side axle to the front differential and hence complete the front drivetrain system.
So, the whirring sound will likely be coming from the TC actuator or the ADD actuator. The pulling to the right suggests the ADD is not working properly and causing resistance to that axle, therefor pulling you in that direction. I would troubleshoot the ADD system first.

Do you know if there is anything specific to look for? In other words what the steps be to trouble shoot this. I took the skid plate off and the vacuum line seems ok. I don't really know what to do at this point.

 

[CookieRoe]

OP: have you tried engaging 4x4 HI by:

1) stop
2) put transmission in "N"
3) switch to 4Hi
3) put transmission to "D"

Doing it this way engages faster (if not instantly) for me. Anyway, rule of thumb, it engages quicker with the drivetrain is nice and hot (a 15 min drive).

Hope this helps.

 

[techno]

Do you know if there is anything specific to look for? In other words what the steps be to trouble shoot this. I took the skid plate off and the vacuum line seems ok. I don't really know what to do at this point.

Before you go tearing into any components, you must establish exactly where the fault lies. I'm only suggesting it's the ADD from your description, but I obviously don't know for sure. Since it's only occurring when you are shifting on the fly, it will be tricky but you could probably come up with a way to pin point it by listening very carefully or having a buddy help out.
If you are pretty sure the noise is coming from the front end, then you must learn and understand how the system works, which is basically like this;
The inboard end of the passenger side axle sits inside a hub (41434) and is not connected to the differential. When told to, the actuator slides a sleeve (41433) over it and then also over the shaft (41306F), making a connection to the diff. Everything is splined, meaning as parts are rotating there will be times when the splines are lined up and times when they are not. I am suggesting the noise is produced by these parts being broken or worn and making it very difficult for them to align while rotating.
Again, this is just a theory but its what I would be looking for evidence of first. Draining and inspecting the front diff oil could also yield evidence, if you find tiny metallic bits that would also indicate metal on metal grinding.
I'm not sure how easy it is to check, but if you can watch the parts working somehow, you might see something that doesn't look quite right.

 

[zerge916]

I have not. I'll go try it right now.
edit: tried CookieRoe 's method and it didn't seem to engage any faster. However, after it did finally go in, it did pop right out of 4hi when I turned it off. Interesting.

 

[NinjaOne]

Before you go tearing into any components, you must establish exactly where the fault lies. I'm only suggesting it's the ADD from your description, but I obviously don't know for sure. Since it's only occurring when you are shifting on the fly, it will be tricky but you could probably come up with a way to pin point it by listening very carefully or having a buddy help out.
If you are pretty sure the noise is coming from the front end, then you must learn and understand how the system works, which is basically like this;
The inboard end of the passenger side axle sits inside a hub (41434) and is not connected to the differential. When told to, the actuator slides a sleeve (41433) over it and then also over the shaft (41306F), making a connection to the diff. Everything is splined, meaning as parts are rotating there will be times when the splines are lined up and times when they are not. I am suggesting the noise is produced by these parts being broken or worn and making it very difficult for them to align while rotating.
Again, this is just a theory but its what I would be looking for evidence of first. Draining and inspecting the front diff oil could also yield evidence, if you find tiny metallic bits that would also indicate metal on metal grinding.
I'm not sure how easy it is to check, but if you can watch the parts working somehow, you might see something that doesn't look quite right.

I'm curious, could a ADD setup be introduced into the full-time V8 system? Not that I would prob. actually do that, but switching to 2WD could be nice

 

[techno]

I'm curious, could a ADD setup be introduced into the full-time V8 system? Not that I would prob. actually do that, but switching to 2WD could be nice

I don't see why not. The front prop shaft would still be turning the diff though, unless you switched to the full multi-mode set up. Would certainly make doing donuts in the farmers fields easier and more fun while the police catch up to you.

 

[zerge916]

Before you go tearing into any components, you must establish exactly where the fault lies. I'm only suggesting it's the ADD from your description, but I obviously don't know for sure. Since it's only occurring when you are shifting on the fly, it will be tricky but you could probably come up with a way to pin point it by listening very carefully or having a buddy help out.
If you are pretty sure the noise is coming from the front end, then you must learn and understand how the system works, which is basically like this;
The inboard end of the passenger side axle sits inside a hub (41434) and is not connected to the differential. When told to, the actuator slides a sleeve (41433) over it and then also over the shaft (41306F), making a connection to the diff. Everything is splined, meaning as parts are rotating there will be times when the splines are lined up and times when they are not. I am suggesting the noise is produced by these parts being broken or worn and making it very difficult for them to align while rotating.
Again, this is just a theory but its what I would be looking for evidence of first. Draining and inspecting the front diff oil could also yield evidence, if you find tiny metallic bits that would also indicate metal on metal grinding.
I'm not sure how easy it is to check, but if you can watch the parts working somehow, you might see something that doesn't look quite right.

But once it does engage there is no noise. So wouldn't that mean that they aren't broken or worn? sorry if I am not understanding something correctly.

 

[TowMeOut]

Do you know if there is anything specific to look for? In other words what the steps be to trouble shoot this. I took the skid plate off and the vacuum line seems ok. I don't really know what to do at this point.

The line is just a breather hose. The actuator is all electric. When I was going through my self-induced headache with my transfer case I got the system "stuck" a few times. I don't have my notes handy but I believe the TC shifts first, engaging the front driveshaft. Once it's spinning the ADD engages. When going back to 2-Hi I believe the order is reversed (ADD disengages, TC shifts to 2-Hi).

A few times while trying to get the timing back in sync my system threw an error because the TC shifting didn't complete within a certain time (my assumption). At least once I ended up in a situation where the ADD was engaged but the TC was not (the system was not happy).

Not sure if that helps but the system is pretty touchy about timing and sequence (I sure wish it was manual shift with manual hubs). Good luck.

 

[zerge916]

Update

Welp. It now magically goes in and out of 4x4 with no issues. I did absolutely nothing to try to fix the issue. I think it may have had something to do with the fact that it was sitting for 6+ months maybe longer. But of course with my luck there's more issues. Weird noise from rear end that doesn't appear to be from the wheel bearings nor the breaks. Going to start researching that one.

 

[Keros]

Everything is splined, meaning as parts are rotating there will be times when the splines are lined up and times when they are not.

Great posts Techno, thanks for that info.

I truncated Techno's reply down because it's likely you had some gunk accumulated in the splines and they were not able to mesh at speed. The syncros in the transfer case have to accelerate the entire front drive train to match the rear drive train's speed... this is all done in a couple of seconds (or less). I would imagine if the solenoid doesn't confirm to the ECU that the front drivetrain is engaged and ready for ADD actuation within a set amount of time, the operation is aborted.

In theory, that would explain why it shifts while stopped but not at high speed.

And all that playing around with it rubbed the gunk off the splines so they all fit together nicely now.

Writing this makes me want to go drive around in 4LO... use it or lose it, as we say around here... I think.

Is that what we say?

*shrugs*

 

[techno]

...
Writing this makes me want to go drive around in 4LO... use it or lose it, as we say around here... I think.
Is that what we say?

It's also what Toyota says

 

[caw901]

Same Problem - Vacuum Specs?

I'm having the same problem. I can shift to 4hi stopped but not moving. The ADD seems to have lost power to engage while moving. Since this appears to be vacuum operated, does anyone have the specs for the vacuum required to operate? I wonder if I could have weak vacuum due to a leak or blockage. The shop manual has electrical specs but nothing on the vacuum needed.

Thanks
Chris
2007 Sport