This morning I attempted to put my 4Runner into 4H to no avail. I tried pumping the brakes as I found in an old similar thread but that didn't work and then I came across another thread where it mentions vacuum leaks.

I recently changed my oil and took off my air filter to clean it so I'm hoping that my problem is just a vacuum leak that I caused when I was removing the intake. The only problem is, I didn't find where these vacuum hoses are.

Where can I find them in the engine bay? Any help is greatly appreciated!

 

Were you driving in a straight line? Try shifting to 4h from stop and and trans in neutral. Then drive forward a few feet. Stop. Drive in reverse a few feet. Repeat.

HTH

Bruce

 

Do you have the multi-mode 4WD? (i.e. Limited or 01-02 SR5)

Do you have relatively the same amount of tread on ALL 4 tires?

 

if it is a 5spd manual--check the vacumm hoses--they come up from the from under the oil pan on the drivers side IIRC. If you find it see if you cant pull a vacumm with a Vac gun.

 

What is your dash doing in response to your attempt to put it in 4wd? Blinking? Nothing it all? Acting normal but not actually engaging?

 

Sorry guys, I guess I left out a few important details in the OP.

I have repeated this several times to no avail.

The car is a 96' 4x4 manual.

The tires all have relatively the same amount of tread.

Thanks. I will look for this.

Nothing is happening on the dash when I switch from 2H to 4H or 4L.

Thanks for all the help guys!

 

i bet its the vacuum switching valve for the ADD. i was having pretty much the same problem as you. it would only go into 4wd sometimes or take a really long time or get stuck in 4wd. i took off the ADD actuator first to make sure that was working properly. then i swapped in a used VSV and that did the trick. if you don't know where any of this stuff is or how to remove it, get a Haynes manual. they will tell you pretty much everything you need to know.

 

The vacuum lines controlling the front A.D.D come off the upper intake manifold here:



From here the line goes to a few solenoids on the left side of the engine compartment. From the solenoids vacuum lines connect to the A.D.D. for control.

There are a few vacuum tube connections between the intake manifold and the solenoids which can be accidentally pulled apart. At one point I had the same problem you have and it was caused by the vacuum lines simply being disconnected.

 

I guess I should also mention the car is a 3.4L.

I went out and took a look for any disconnected hoses to no avail. It is supposed to snow for the next few days and I'm hoping to get this figured out today. Anybody have any other ideas?

 

I think I remember reading somewhere that the dash indicator is actually part of the circuit for initiating the 4wd? Anybody able to back that up or refute it? Reaching at straws, but I just saw it a couple days ago.

 

yeah, you have two switches in your 4wd system, one in the tcase one in the ADD tube.

when you switch the tcase it signals the 4wd ecu and opens the right solenoid to lock or unlock the add. and when both the add is switched on and tcase is in 4h or 4lo is when the light comes on.

you could try spraying brake parts cleaner or starter fluid around where you think the vaccum leak is to try and locate it, you will notice a change in your engine when the flammables are sucked into the engine.

 

Can you verify that the t-case actuator is moving? It's electric, and it will make a whirring noise. Also, try L4 - if it engages in L4 then it narrows things down a bit. If the t-case actuator is not moving, or if it engages fine in L4 then you need to be looking for an electrical problem, not a vacuum leak.

 

only if he has push button 4wd. if not, then there is no transfer case actuator. just the ADD actuator.

as i said, i would check take off the add actuator and see if it moves freely. if so, measure the vacuum going to the actuator. in 2wd, one hose should have vacuum and the other should have nothing or very little. when you switch to 4wd, they should flip. if they don't then your need to replace the vacuum switching valves

 

Well unfortunately it has been snowing and temps in the single digits for the last few days so I haven't really had a chance to go and play with anything yet.

I did find an unplugged hose, but it's one that plugs into the arm of my K&N intake. Hopefully it's just another unplugged hose somewhere!

 

Well I've had a chance to take a look. I could only find 1 hose unhooked and that was the one that's supposed to be attached to the intake arm.



The car does not have the push-button 4WD, it is the shift. Thanks for all the help guys.

EDIT - *UPDATE*

The car engages in 4L, however, the dash does NOT blink or stay solid with the indicator.

4H still does not engage and nothing is indicated on the dash.

 

does it actually engage 4wd or does it just go into low range

 

I'm pretty sure it just goes into low range. It doesn't feel like all 4 wheels are powering the car.

 

have you checked the add actuator yet like i said?

 

Yeah, I took the hose off and there is vacuum to the line.

 

well there are 2 lines to the actuator. make sure that there is substantial vacuum in one and little to none in the other. and verify that they switch when you put it in 4WD