Ok having an issue with my 4wd on my 98 SR5 4runner. Stats: 3.4, AT, standard transfer case (no push button multi mode). Noticed a month ago when I went into 4Hi the dash light did not come on; about a month prior went a 3 day offroad trip and the system worked flawlessly. Figured it was just a burned out bulb, since I was traveling around 50-60 on fireroads and truck seemed pretty stable. This weekend in a dirt parking lot I wanted to see if the 4wd was engaging, so I put the lever in 4hi, and broke the tires loose. The person outside the car said only the rear wheels spun. I’ve read a few threads about similar problems but they usually involve the push button transfer cases and involve blinking lights, versus no light. Checked & replaced, (even though it looked good) the 20 amp fuse in slot 22 under the dash, but no change. Looking underneath the car I see the one plug that goes into the diff with the wire harness, and the two vacuum lines. Is there a way to test the switch on diff w/o removing it? Looks pretty tight. Any good next steps?
If there is a good write up on this please send it my way.
thanks Josh

On a side note, figured out how to tune SWRs on my new CB antenna mount and location so if anyone nearby needs to borrow a SWR meter or needs some help tuning an antenna-PM me.

Was the person that saw only the rear tires spin on one side of the vehicle? The front diff is open and the tire on the other side may have spun.

Well come to think of it he was sor tof diagonal to the truck saw I think he would have seen it, since he noticed that the driver side rear was spinning rather than passenger side.

Josh

Could be the ADD.
I would jack up the front (support with jackstands) and try a few thing.
(all tests done with the rig turned off and done by hand)
* 2wd, Spin the pass wheel- nothing else should move.
*2wd, spin the drivers wheel- should feel some resistance and the driveshaft may move a little.
* 4wd, spin the pass wheel- drivers wheel should rotate backwards
* 4wd, spin the drivers wheel- pass wheel should spin
* 4wd, try to spin the front driveshaft- shouldn't be able to turn it.

I don't know how religiously people follow it or if it really matters, but the max recommended 4-high speed in the manual is 45 mph for us with 4runners with non-awd systems.

Check the vacuum cylinder inside the driver side wheel well for abnormalities. I'm pretty sure that has some function within the 4wd system.

That isn't correct. You are supposed to be below 50MPH in order to shift into 4HI, but there is no top speed for driving in 4HI. That is according to the owners manual, and the card in my visor. Post a pic of your manual if it says differently.

There are a couple thread on here about how to test the vacuum pressure in your 4WD system. It is pretty common for the valves to get gummed up and stop working. You can swap some vacuum lines to determine if one of your valves isn't working. I don't know the details, but I know it has been documented here somewhere.

Totally right Nelson, I just checked the manual. Disregard my first statement josh, it's filled with nonsense.

Ok, Chris
spin either passenger or driver wheel in 2wd other one does not move.
move transfer case into 4hi same thing. Both done with rig off, do I need to start it on the jackstands and put it in 4wd? Heard somewhere you need to build p a vacuum to engage it, even though it just has the transfer case lever. (warning may be puling this out of my a$$)
Any idea how I test the relay that is coonected to the front diff?
thanks josh