v8 running in 2wd instead of 4wd

I have searched high and low for some post with the same issue but haven't found it if it's there (point me there if you know)...
Bought a used v8 2004 sport and test drove it before buying it and it showed itself powerful and shifting into 4Lo and locking diff but a month after buying I was on some ice with fresh powder on top. Trying to pull out and head downhill I lost all traction. Believing I was in 4Hi already, I was totally shocked. ZERO traction with offroad dirt tires (didn't expect them to be great) and slid sideways for about 50 yards, wheels not grabbing.
I shifted into 4Lo and locked my diff and made almost no difference. A friend jumped in and I got to see the lack of wheel spinning for myself--I had rear wheels spinning in 4Lo locked diff but absolutely no spinning or action from the front.
What is causing this to happen if I am supposed to always be in 4Hi as a baseline?
Any troubleshooting pointers would be great.

 

Downhill on ice is a challenge unless you have studded tires or chains.

 

Well, you were on ice. What you are describing is pretty much what I would expect to happen on ice.

What you are describing where you tested 4HI/4LO sounds like the actuator for 4LO isn't engaging. The V8 trucks are full time 4WD so 4HI should be working no matter what. Solenoid/actuator failures are very common on these trucks. Do a search on the forums and you will see lots of threads on the issue.

 

Ya if you were in 4LO and only the rears were spinning something sounds like it’s not actually engaging the 4wd system.

 

Thanks for the tip xtremewlr. actually, 4Lo is engaging but it's only 2lo since the 4wd full time is not full time. you can see why I am so confused...!

 

If you have a 4WD V8, you have a full time 4WD system. If it's only doing 2WD, then you are missing a front driveshaft or something is broken in the front differential or the transfercase.

4th gen 4Runners with the V8 option and 4WD only came as full time 4WD. That's why the shift knob on the dash only shows 4HI or 4LO. There was no 2WD option unless it was a V6 4WD 4Runner.

 

Did you try the center locker?

In normal driving the center isn’t an open diff but it is limited slip.

(not entirely sure if it applies but with no brake intervention, wouldn’t the torsen center act like an open differential if one end is completely freewheeling?)

 

Thanks for the ideas--keep them coming in. do any of you have a line on diagrams that would show the entire 4wd system? I am needing to learn this system a lot better than I know it right now before I make some very expensive decisions! I haven't been able to find a diagram that shows the whole system. I am looking for something that shows the front and rear diffrentials, transfer case, actuators, etc.

 

Go try out the center locker button (don’t use on dry pavement) and see if you get the front wheels spinning then. That’ll probably be the fastest way to see if power is going to the fronts as it should IMO.

 

Best thing you can do is crawl under your truck and just lay there looking at everything. The only actuators on the V8 4wd system are on the back of the transfercase, in a black, plastic box. Front differential is mostly covered by the skid plates in the front under the engine. There is no axle disconnect on the V8 4wd 4Runner like the V6 variants have.

 

The pictures in this post should help some.

 

Would also like to know what’s going on here. I recently purchased a v8 limited and the front drive shaft is not spinning in full time 4wd or 4lo. With the centre diff lock engaged I can get 4x4 working. Obviously there is a transfer case issue but how is it possible in the “awd” Torsten centre diff. There is no grinding or other odd noises. Drives fine otherwise.

 

^How are you checking this? Vehicle on a lift or jack stands such that all four tires are off the ground? With the transmission in "D" and rear tires spinning at idle, engage a few clicks of the parking brake, and see if the front driveshaft starts turning.

 

4 wheels on ice against a snow bank. Left in drive got out and only rear driveshaft and one rear tire spinning. I will try the parking brake. Never thought of that but even droving through snow it would not spin the front.