I apologize in advance for the long post:
First:
2001 Limited, 4WD
280000 miles
Owned about 3 months
On 11/3 I was going about 10 MPH and pressed the 4WD button on the transfer case shifter.
· Drove on pavement about a mile under 35.
· Very suddenly it started making a roaring sound from the front followed by a crunch and a jerk.
· Then it stopped moving. I turned 4wd drive off (took awhile for lights to turn off on dash).

Limped back home while it sounded like gravel in the front end, under the foot well. No warning lights. Nothing appears obvious from underneath. Looking at axles and differential and they are dry and free of leaks. It’s got 280k and no evidence of any off-roading, I’ve had it in 4wd several times to test it and to familiarize myself with the truck and no issues until now…

Update and help request (again, sorry for the long post):
Turns out the Front Differential had failed. When it failed, the driver’s side CV axle shaft failed as well. I found a lower mileage (160K) front differential from another 2001 Limited. According to the VIN tag, it too had 4:10 and ADD. It seemed in good shape; no play in the shaft, splines looked clean (we didn’t open it up). We swapped out the differential, both CV axles(new)and filled the differential to the proper level (until it started to come out) with the recommended oil.
· Drove in about 5 miles in 2WD with no issues
· From 4L, I placed the transmission in Neutral, returned the shifter to H, and pressed the button to turn off 4WD. The icon flashed and remained flashing even as I drove slowly around for about 5 minutes.

Turned off the ignition and started it back up and lights were off.
Returned to paved road and drove 2 miles in H with 4WD button off and all was good.
While going about 30, I pressed the 4WD button the truck immediately began to pitch forward (almost like the e brake was on) and the loud moaning returned. I immediately put transmission in neutral, then transfer case in neutral and turned off the button. After waiting a few minutes to choke back the vomit, I returned the transfer case to H, Icon lights stayed flashing and moaned for the 1000 feet it took to get back to the house (at around 5 MPH).
There it sits…
Any ideas?
Thanks in advance

Search the forum here. For how to check your gear ratio and double verify your front and rear ratios match.


If they do, I start looking at your transfer case as something is majorly wrong.

That is where I would start.

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Will do, thanks! Would a problem with mismatched ratios surface while in 2wd?

Thanks again

Also, not sure if your 2001 has the AWD option for the transfer case, but just moving forward it is strongly advised that you DO NOT use 4WD on dry pavement (unless the AWD option is confirmed).

Did you open up the old front diff? I agree with @brillo_76 that you should also be looking at the transfer case.

I was, for no particular reason, pretty sure my car had 4.30 gears, since it was a factory e-locker, and it seems as though pretty much all the e-lockers I have ever seen were 4.30's. So when my rear end got a little noisy ('dry' sounding pinion bearings, not sure why) I got lucky and found a good e-locker diff at a pick-n-pull. Verified it was 4.30, swapped it in. And I even did a fair amount of wheeling with it, with no issues at all. But I did notice that I *always* had to back up to get it out of 4WD. And while I pretty much never ever use it on pavement, once I did it on a slippery bit of pavement - headed uphill from a stop onto a highway, and DEF noticed something was off.

So in the driveway, I engaged 4WD, jacked up front and rear tires on one side, put it in neutral (5 spd manual) and then rotated the tires and watched. Lo and behold, they drifted apart as they turned. I apparently had 4.10 gearing. After pondering a bit, I just decided to make them match by getting a 4.30 front diff to match the rear.

If your 4 runner is AWD I would think so. I don't know if you have a J transfer or a 2 position transfer. Most of the newer 01 and 02 and limited had the Newer AWD transfer case.

So that is where the problem comes in. The J transfer cases are not AWD. They can not be driven on dry pavement roads as they will bind up. Where the AWD transfer cases can.

I just wanted to give you a place to start looking. Also, many users have pointed out that the stickers in the door jam do not match the Rim size and sometimes the axle ratio.

Most V6 autos have the 4.10 ratio however, not all and that causes some major confusion as well.

We didn’t open the differential. The oil had metal in it when drained.
Looking at the owner’s manual it seems that with transfer case in “H” with 4Wd button in it is Ok for dry conditions.
In “H” with 4wd out, there was no issues.
From the manual:

􏰁H" mode (high speed position, two− wheel drive): Front drive control lever at 􏰁H", 􏰁4WD" button left out
Use this for normal driving on dry hard− surfaced roads. This position gives greater economy, quietest ride and least wear and better vehicle control.
􏰁H" mode (high speed position, four− wheel drive, center differential un- locked): Front drive control lever at 􏰁H", 􏰁4WD" button push in, center differential lock switch left out
Use this for normal driving on all types of roads, from dry hard−surfaced roads to wet, icy or snow−covered roads. This position provides greater traction than two−wheel drive.
􏰁H" (high speed position, four−wheel drive, center differential locked): Lever at 􏰁H", 􏰁4WD" button pushed in center differential lock switch pushed in
Use this for greater traction when you experience a loss of power, such as wheel slipping, in the center differential unlock mode.
114
􏰁N" mode (neutral position): Front drive control lever at 􏰁N"
No power is delivered to the wheels. The vehicle must be stopped.
􏰁L4" (low speed position, four−wheel drive, center differential unlocked): Front drive control lever at 􏰁L4", center differential lock switch left out
Use this for maximum power and traction. Use this for climbing steep hills, off−road driving, and hard pulling in sand or mud.
In this mode, the braking feeling that oc- curs when the wheels are negotiating a sharp corner is further reduced than in the 􏰁L4" (low position, four−wheel drive, center differential locked) mode.
The transmission automatically shifts up from second gear in this mode. This sys- tem is effective when starting your vehicle in sand, mud, ice or snow. (However, the transmission system may shift up from first gear when the vehicle starts too quickly.)

It has the 2 mode shifter. H, N &4L. There’s a 4wd button on the shifter. I’ll have to really have a look at the ratios. I made the call based on my VIN sticker and the VIN sticker of the donor. Both indicated 4:10. Mine does not have a tow package and no indication it was swapped. Should have checked the “new” one...

That's the newer transfer type which is should have. However, we never know what PO do.

2000 should be the last year for e locker as VSC and trac took its place. So you shouldn't have a diff lock unless someone in the Past changed that.



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It has the center lock, not rear lock. It’s a 1 owner, she’s not the off road or modding type. In fact, I doubt it was in 4wd often at all since it’s been in Atlanta the whole time.
Thanks again for the help!

got to agree here. in 2wd it wont matter what the gear ratios are if NOT AWD
but if not AWD, when you kick into 4wd or locked transfercase it WILL matter big time

also...vin number should give correct ratio...I have seen errors on door stickers...not so much on a 4 runner...other than wheel size...but have seen errors on other cars

Ah well that's good to know then its all mostly factory then.

The Center non lock transfers was a big upgrade. No longer have the on no I left it in 4WD deer in the headlights look when you been on a clean road for a few mins..lol

Georgia doesn't see a lot of snow..

That is what we are here for. :-)

As for diff ratios, there has to be 15+ threads that show the VIN is *not* a reliable way to determine the ratio.

Since the same thing happened twice, I'd look at the parts you didn't change over.

Good luck!

2001 Limited is always 4.10 ratio. Anything else means someone modified.