Truck engages and disengages in and out of 4wd

[GSPRunner]

In Montana currently, on the way home to Seattle. 2000 Limited MultiMode TC. Used 4LO and 4HI quite a bit yesterday in the mountains on rocky rutted forest roads, and now the truck won't permanently shift out of 4wd. I drive it and it pops out, but keeps popping back in and out randomly. Anyone know what the cause might be?

 

[TheDurk]

Probably weak vacuum. Check the check valve--little cylinder in the line from intake manifold to the VSVs on the drivers fenderwall. Blow through it, it should only flow air towards the engine. Cheap fix. If that's not it, you need a hand vacuum pump to test if the rest of the system holds a vacuum. If it doesn't, use golf tees to isolate pieces of the system until you find the leak. You can at least check visually for hose issues and look at the condition of the reservoir can under drivers fender at the front.

 

[csp]

Just an FYI, you moving the transfer case lever takes it out of 4WD. The ADD may not be disconnecting the internals of the front axle, but the tcase shifter disengages the transfer case so that no power is going to the front axle.

 

[88toy4x4]

Just an FYI, you moving the transfer case lever takes it out of 4WD. The ADD may not be disconnecting the internals of the front axle, but the tcase shifter disengages the transfer case so that no power is going to the front axle.

In his case(since he has a limited model with multimode), the initial shifting to 4wd is by the button on the side of the transfer case shifter. I agree with TheDurk, probably a vacuum leak or a bad hose going to the solenoids on the drivers side inner fender(under hood) or to the canister in the drivers wheelwell.

 

[GSPRunner]

Thanks guys, I ended up pulling the vacuum lines on the front diff so I could at least drive it home the 700 miles at freeway speed. Just pulled it into the garage to start to troubleshoot it. I'm thinking it's weak vacuum also.

 

[GSPRunner]

[MENTION=63487]A.Wilson013[/MENTION] and I spent a fair amount of time trying to track down the issue today. All vacuum lines are good, check valve good, swapped VSV with Alex's and the issue remains. Changed out the transfer sensor on the front diff, no change. Haven't tried the actuator but it's clearly working since it's going in and out. Any more ideas [MENTION=10169]TheDurk[/MENTION]?

 

[TheDurk]

Ok, please clarify one thing for me. You say it is popping in and out of 4wd. Are you going by the 4wd light on the dash, the feel of the truck as you drive it, or both?... because I would have different approaches based on that answer. Please give me some real detail on the "issue". Thanks.

 

[A.Wilson013]

Ok, please clarify one thing for me. You say it is popping in and out of 4wd. Are you going by the 4wd light on the dash, the feel of the truck as you drive it, or both?... because I would have different approaches based on that answer. Please give me some real detail on the "issue". Thanks.

Both.

It spends most of the time in 4wd (hi) with the center diff locked. However, the shifter is in the 2wd position. Shifting it between 2wd and 4wd does nothing. The lights on the dash function showing the green tires, and orange center piece locked.

It seems to pop out of 4wd and into 2wd (both the lights on the dash and the feel of the truck) often while he's turning. However, it'll occasionally do it when he's just sitting at a stop sign, or driving straight down the road.

As for frequency... we drove about a mile yesterday. And it popped into 2wd probably 6 times or so. It was never in 2wd long. Typically a few seconds.

I think it'd be more accurate to say, "Truck is stuck in 4wd, and occasionally pops into 2wd".


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[amalik]

You multimode people sometimes confuse us less fortunate standard 4wd folk. So basically you're stuck in the equivalent of AWD with the intention of going 2WD... (Which would destroy your driveline on dry pavement if you weren't multimode, that would blow!)

You mentioned the actuator works, but what sends a signal to the actuator to do its work in the first place?

To me, I'm a noob but, I'm thinking the 4wd button on your shifter is no good, otherwise it's impossible to even enter AWD while your shifter is in 2wd. Meaning, you "unclick" the 4WD button with no results.

How do we test that button?

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[A.Wilson013]

You multimode people sometimes confuse us less fortunate standard 4wd folk. So basically you're stuck in the equivalent of AWD with the intention of going 2WD... (Which would destroy your driveline on dry pavement if you weren't multimode, that would blow!)

You mentioned the actuator works, but what sends a signal to the actuator to do its work in the first place?

To me, I'm a noob but, I'm thinking the 4wd button on your shifter is no good, otherwise it's impossible to even enter AWD while your shifter is in 2wd. Meaning, you "unclick" the 4WD button with no results.

How do we test that button?

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I also have a J shifter and this multimode crap blows my mind.

He's stuck in TRUE 4wd and it occasionally shifts into 2wd, regardless of shifter position.

I always wanted multi mode, but now I'm not so sure haha

 

[amalik]

I also have a J shifter and this multimode crap blows my mind.

He's stuck in TRUE 4wd and it occasionally shifts into 2wd, regardless of shifter position.

I always wanted multi mode, but now I'm not so sure haha

I think you have it backwards, friend. Or i'm about to confuse the whole thread.

Hear me out for a minute.

With the shifter in 2WD as you and OP both mentioned, (AKA H2), the push button enables H4 UNLOCKED according to Brian's write-up explaining these differences among the 3rd gen years.

http://www.toyota-4runner.org/3rd-g...rs-3rd-gens-transfer-case-awd-multi-mode.html

This 4H being unlocked with the button makes the 'AWD' possible in the first place. Center diff being unlocked allows front and rear driveshafts to spin at different speeds and not bind.

This should be OP's shifter for the 00 Limited with Multimode (Taken from the write-up):

Look again, the H4 on the BOTTOM of the shifter even has a little L next to it indicating its 4-High-Locked. This is more evidence the H4 associated with the push button in the 2WD shifter position is 4H unlocked/AWD.

So, going back full circle to my point about the button on the side -- When he is in 2HIGH on the J-shifter but the truck is still driving in 4H unlocked (AKA AWD), the side button (or whatever it controls after you click it, signal to the actuator, etc etc) is the only way 4WD is even possible in the truck; intentional or accidental.

That's why I'm saying focus your attention to the flow of that button.

I got my popcorn out and am awaiting the Durkster's comments on how to proceed

Regardless of the issues, still wish I had Multi-mode as having the option of going AWD on-the-fly is pretty awesome on dry pavement (Whereas traditional 4WD only allows it on wet/snow/icy/etc).