andyf0722

My 2000 4Runner SR5 will no longer shift into 4WD. This is a manual shift with the second shifter for 4WD. The one without the button on the side.

I was driving about 2 hours north where there is snow and ice yesterday and couldn't get it to shift into 4WD Hi. The shifter moves into position without problem, but the light does not come on. Also I had no traction on an icy parking lot that is at the end of dirt road that had been plowed to a smooth layer of snow that iced over. I was able to get around slowly and carefully with just 2WD. The part that made it very obvious that the 4WD wasn't engage was when I got the end of the dirt/ice road. At the point where my front tires were on the pavement and my rear tires were on ice I could spin my tires until the rear tire raeched the pavement.

Cut to today when I am back home where there is no snow or ice to test with. I verified that I still couldn't shift into 4WD Hi. I moved back and forth and turned the wheel to see if I could get it to engage. When it was working some movement was often necessary to get it to engage. I checked the fuse and even swapped it with the wiper fuse to ensure the fuse is good. I decided to test 4WD Lo. The light doesn't come on but it does drive differently. I can't be sure if it is 4WD or not. I have no snow or ice to slip on, but pavement isn't dry either to feel the bucking you get when doing a sharp turn on dry pavement in 4WD.

I think I have only use 4WD Lo once in 8+ years, so I am not sure what it should feel like. I don't have a lift, jackstands, or a dynamometer to see if the front wheels spin or not. How can I tell otherwise if I have 4WD or not in Lo gear? Also if it weren't 4WD would shifting into 4WD Lo still feel different?

Any suggestions of anything else I can test to isolate the problem without getting too technical? I don't mind crawling under the vehicle but am reticent to taking anything apart. I'll take it to the mechanic tomorrow to see what they say but I'd like to know as much as I can before doing so. Thanks.

littlecommando

you should be able to just tell if it is working or not.

even if your 4wd isnt working, 4lo will feel different, it has more gears, and is slower

andyf0722

That is kind of what I thought, but wasn't sure.

littlecommando

this doesnt really help you now, but if you dont ever use your 4wheel drive, it will stop working, you should use it at least twice a year for proper lubracation

crolison

sounds like your add isn't engaging... especially with no 4wd light... in 4hi and on pavement you should be able to tell and hear it in 4wd.

andyf0722

I do use 4WD Hi, but rarely Lo. Is the use of Hi good enough to keep it lubricated for Lo also?

cackalak han

Yes, 4HI or 4LO will do.

One way to find out if it's working is have a friend look at the front driveshaft while you drive very slowly. If it's turning, then it's working.

Could be the actuator that could be bad. Could be wiring. Could be a vacuum leak.

crolison

I highly doubt the tcase is messed up, maybe the switch in it is..... i dunno when they switched to electrical add, but if you need any add parts and yours is vacuum i have a whole add diff tube dissembled at home.

trbizwiz

If it is the add, you might look into converting to manual hubs. It may be cheaper and when you do your solid axel swap after everyone sends you a dollar, you can resue the manual hubs then too.

crolison

Rough estimate to do 300-500 bucks for manual hub conversion, vs prolly around 100 (high side) for a new add diff tube. Plus you'll lose abs with the manual hubs, unless you wanna spend more $$ for bearings and seals.

Ironmike4x4

My owner's manual recommends once a month for at least 5 miles. As far as knowing if your 4x4 works on high you have 2 options. The hard way: jack up the vehicle and put 4 jackstands and slowly engage 4hi. The easy way: engage 4high and make a hard right or left turn. If you feel a significant drag then it's working. Make sure you check 2 wheel drive to compare the drag if you aren't sure what I'm talking about. The 4low then just put on and you'll know if it crawls very slowly.

Adam F

Not so. Only real way is to jack the truck up on all 4s and put it in 4wd. Or on a dry surface and make a sharp turn and feel for binding.

Reason is, the ADD stuff is in the differential. So even if you have it in 4wd, and the transfer case is doing its job, power will go into the diff, but if the ADD stuff isnt working, power isnt being sent to the wheels, and no 4WD.

crolison

The power is being sent to the differential then its being sent to the drivers side wheel, but because of the spider gears the diff just spins.

andyf0722

I was able to verify that the front drive shaft does run when I shift into 4WD. I used my digital camera to record a video. I backed out 10 feet in 2WD, then back forward. Stayed in a straight line to not run over the camera. Then I shifted into 4WD Hi and backed out and in again. The video is very clear. The front drive shaft did not budge on the first pass. Between the first and second pass when I shifted the front drive shaft moves slightly. Then on the second pass it is clearly spinning.

So I guess this means the transfer case is not the issue, but the ADD could still be the problem. Or anything beween there and the hubs.

For those with an interest the video can be viewed here

crolison

The only thing between the ADD and the spindles is the cv's. The spindles always spine the cv's...

andyf0722

The problem that occured back in December happened again today. To summarize, it will not shift into 4WD. The front drive shaft does spin when I engage 4WD and doesn't when in 2WD, so it is not the transfer case. However I do not get 4WD and dash light does not turn on. This happened back in December but mysteriously fixed itself. Now it is back. I don't want to rely on it fixing itself this time.

So the problem is between the front drive shaft and front wheels. The ADD has been suggested. Any other suggestions or tests I should do? What components are there. Can someone give me a description like shin bone is connected to the knee bone, knee bone is connected to... Or rather transfer case is connected to the front drive shaft etc...

ScubaDuck

The below webpage is a write-up for "defeating" the ADD system, but the first part should give you an idea of what is going on:

http://www.4x4wire.com/toyota/tech/add/

Based on my understanding and using the terms from the above site:
Your 4wd is not engaging because the "actuator" is not moving the "sleeve" inside the axle housing. The two common causes of this are: 1) the sleeve is gummed up from non-use, so the vacuum pressure is not sufficient to move it, or 2) there is not enough vacuum pressure (due to a vacuum leak, crimped vacuum line, etc) to force the sleeve to move.

Hope this helps-

-Scubaduck

Zuke79

Does anyone have experience with the method of "defeating" the add system described in the article? Does it work well? What is the best way to lock the sleeve in place (hose clamp)?
I am having the same problem as the OP and I am tired of digging through vac lines and checking relays with no luck on finding the issue. I am putting manual hubs on this week end if it stops raining.