khann

1a) in front diff - VACUUM
1b) in Xcase - ELECTRIC

Testing vacum act. is possible with piece of hose and large syringe.

Are the lights on dashboard flashing constantly? Does change (switch or lever) give any reaction on lights?

Usually switches are best starting point to find out problem. If You want to save money and have some ability to lift a bit the vehicle You should do test em.

Atomicpunk

First post, would like to thank everyone here for pointing me to a problem I was having with my 2001 4Runner. It was making me crazy trying to figure it out so I looked here and here was the "missing link". Had my mechanic check the sensors and there was a wire disconnected. He connected it and now all is well. Couldn't have been any easier!
Thanks to all who shared their knowledge and experiences in this thread!

Rock Slide

iTrader: (1)

Sad to report my '02 4Runner fell victim to 4wd limbo today...on Easter no less.

Driving down the road, depressed the M/M button on the shifter to lock into 4HI, 4wd indicator starts blinking...but I never hear the "clunk" as normal when the 4wd engages. The 4wd indicator just kept blinking. Although, I'm confident I'm in 4wd (as I can feel the front tire(s) pulling the vehicle on acceleration and deceleration), the 4wd indicator light will just not stop blinking. I depress the M/M button to release 4HI and go back to 2HI, but the lights still continue to blink and the truck still feels like it's in 4wd.

Guess I got some troubleshooting ahead of me...

jfryjfry

start checking switches. they are fixable but timeconsuming and ugly as they're crimped together. someone here posted a link to some waaaaay cheaper part numbers from rock auto (and presumably your local napa, autozone, etc). hopefully just one of the easy-to-access switches.

Rock Slide

iTrader: (1)

Well, I live close by a dealer and know the lead tech well enough that he'll shoot me straight free of charge (we've been friends since way back). Called him up and said they've have two '02s come in over the last mo that had the actuator in the t-case go out. Ouch.

Dropped it off with him this am (he told me I owed him a good lunch). He just called to say all the switches were good and was able to trick it back into 2wd as other have mentioned doing. Said it is in fact the actuator in the t-case that's gone bad. Bummer. Not going to do anything on it yet...may just look into used t-cases. I've got some buddies that may have a few for cheap.

I'll keep you posted.

jfryjfry

i'd be surprised if it was the actuator, but it's possible. let us know what happens

Rock Slide

iTrader: (1)

I agree. IMO, a senor (or two) gone bad seems much more likely than the tcase actuator going out...thus I'm still going to replace a few sensors before I do anything. At this point, I have nothing to loose with replacing a few sensors first.

99SC4Runner

I would personally test each sensor one at a time with a multi meter. It still sounds like it could be a switch/sensor and not the actuator that is faulty.

Rock Slide

iTrader: (1)

Buddy said he tested them all, but I agree, I need to do it myself to confirm.

Remind me, how many switches are there? Something like 4-6 total right? And when using the multimeter to test each one, what reading should I be looking for? (i.e. to know if they're on the verge of failing or not.)

99SC4Runner

IIRC, there are 5 switches on the 99 Limited t case. Just pull each switch/sensor out one at a time, and then use a multimeter set on Ohms reading. Then hook the neg and pos leads from the MM one on each pin, then while holding them on the pins depress the ball in the switch. If it doesn't tone up each and every time, then that switch is probably causing the 4wd circuit to not make contact to go into full 4wd mode.

You might be able to clean the switches somewhat, but they are cheap enough, I'd just replace them.

Rock Slide

iTrader: (1)

Ok great. As soon as I get some free time, I'll crawl under there and test them.

sharrack

i've always had good luck with just reversing the truck then into drive once or twice and it goes back to 2wd

sharrack

Holy sheet Simaan.......thats alot of cabbage!!!!!
Thats about a third of the trucks worth!

Rodzilla

I would just like to say thanks for everyones input (1st post btw) I joined because of this thread. Mine is a 97 limited @ 106k miles. Just bought it bout a month ago, I new it would come out of 4wd, but I had to press the button on the xfercase (for 2wd) then place in park and switch the engine off and back on again, then the 4wd lite went off. Later I tried turning my front drive shaft by hand with no luck. I tested the front diff switch, an the easier to get to switch on top of the case but now I'm thinking i may need to do a retest. I put 12v 2amp to pin 2 an 3 on the act. and it proved to work both in and out. I left the t-case in 2wd for now till I have more time to test, who knows, that may be all it took.

khann

welcome Yotatech rulez

Rock Slide

iTrader: (1)

Somewhat of an update here - Had just a few minutes of spare time this morning, so I pulled the rear most sensors on the back of the tcase (the ones highlighted in blue below). I did multiple tests using my multimeter, but both switches toned up each and every time. Bummer.






FWIW, here's a few photos of a tcase on an '02 4Runner. You'll notice the 6-pin plug harness and directly behind it, the 2 rear switches that I tested earlier:





Moving towards the front of the vehicle, here's a few more shots...following the grey and blue plug harness, 2 more switches are located near the top of the tcase (I have not had a chance yet to pull those and test):






Last photo, an exploded diagram of an '02 front diff:

Rock Slide

iTrader: (1)

While killing time at work, I called up 2 places that sell used toy tcases. First one, '01 4Rr 78K miles - $300.00 for the tcase. Second one, '01 4Rr 52K miles - $450.00 for the tcase. Both come with a 90 day warranty.

At least I know I can get a cheap case if all my switches check out...

Rodzilla

Chalk another one up for the good guys my t-case works perfectly. Seems all it needed was a little action. The 12v 2 amp charge to pins 2 an 3 on the act. plug worked it in and out of 4wd and freed itself. By taking time to check everything and with the help of this thread I saved a pile. I too had looked into used t-cases, be careful, make sure it has the act. on the back, some I saw on line looked as if it had been removed . Again thanks to all.

Rock Slide

iTrader: (1)

Nice work Rod.

No good news for me. All sensors checked out ok. Did a few 12v tests to the plug; I could hear the actuator tying to move in and out, but seemed to be binding. Never would engage 4wd. Looking hard into used tcases now.

Rock Slide

iTrader: (1)

**UPDATE**

4wd is fixed now. Turns out, it was the small electric motor that needed replacing. Look a few posts up and you'll see it pictured in the pics I posted. The small electric motor is the heavily rusted circular looking cap that sits right next to my 6-pin plug connector.

I was able to swing by a local pull-a-part and rob the motor, plus the black cover it bolts to for cheap. Unbolted the 3 bolts that hold the cover on, pulled the vacuum line, popped the cover/motor off, then mounted the new cove/motor on & reinstalled the vac line. Took all of a few mins to swap out parts. Now, when I push the 4wd button, the system turns on and off better than new.

I was able to diagnose it down to the motor by doing the following: Had a friend sit in the truck, turn the key to ACC, push the 4wd button and then I tapped the small electrical motor w/ a hammer (just as you would tap the starter in the engine bay w/ a hammer to free it up). The elect motor would engage and disengage 4wd as I did this, regardless if the 4wd switch was depressed or not...thus, we knew it was the elect motor that was bad.

Later that day, I drove over to my local dealer to show them the failed part and to see how much a new elect motor costs. Get this, toyota does not sell this motor & cover as individual or mated parts...you must purchase the entire actuator assembly as the elect motor is bolted to it. What a joke...very disappointed toyota saw the need to design this part like this. Seriously, the black cover is just held on by 3 bolts; you should be able to purchase the motor separately from the actuator. Oh well, at least I found the problem and was able to fix it for less than a tank of gas...much cheaper than the cost of a new actuator replacement.