I want my 4WD back

I bought my first truck a few months ago, 2002 Tacoma 3.4 Manual with 184K miles. Does not have the 4WD push-button on the stick. Been an awesome rig, can't thank this forum enough for help with other minor problems. 4WD stopped working recently and I'm looking for some help.

I'll try to lay everything out clearly:

I drove 20+ miles in 4WD about a month ago with no issues, but two weeks ago I tried to shift into 4WD and it didn't work. I found that when I put it in 4WD the front driveshaft spins, but the dash light doesn't come on and I don't get any power to the front wheels (tried to climb a couple muddy hills and only the back wheels spun). It goes into low range, but still no dash light or power to the front wheels (just "2LO").

After the last time I used the 4WD, I drove about 900 miles up I-5 to my family's home in Oregon for the holidays. Maybe something got loose or developed a leak during the big drive. I also changed all the fluids about the time I last used the 4WD, cant remember if I changed them the day before or day after but I did front/rear diff (

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 GL5 non-synthetic) and transfer case (75W-90 GL5 synthetic w/ lsd additive [no other option]) to the factory recommended amount.

Been scouring the internet trying various things to fix the 4WD (checked the 4WD fuse, banged on some stuff, nothing looks unplugged. I grew up driving old trucks so I know sometimes you have to roll a few feet forward/backward to engage) but no luck. Any help would be greatly appreciated.

The ADD on the front diff, looking forward.


Transfer case


I believe these are the hoses that come from the front diff ADD, they just stop so I'm guessing they're only to vent? This is on the driver wheel well.

 

Welcome to TW

 

Correct. This is oem diff breather

 

Thanks!

So is my ADD electronically actuated then? Should I look into the little motor in there possibly being the issue?

 

your front differential looks to be electronically controlled. Does your transfer case shifter have a 4wd button on it? It’s possible that the 4wd computer went bad.

 

It does not, so I figured it was vacuum controlled, but I don't see any vacuum hoses

 

02 ADD is electric

 

Hope this helps @guackillz
http://www.4x4wire.com/toyota/tech/add/
More to come
Welcome to TacomaWorld

 

http://www.off-road.com/trucks-4x4/tech/the-automatic-disconnecting-differential-system-19259.html

 

Long read but touches on most aspects of your possible causes and fixes
https://www.tacomaworld.com/threads/broken-4wd-engagement-whats-likely-broken.579256/#post-19211465

 

Those first two links are very informative but appear to be for troubleshooting vacuum activated ADD's... I'm thinking it's definitely electronic like you said (even tho there's no push button) because I can't find solenoids where other people have em and it looks like just one hose and one electrical line to the ADD as per my pic. That last thread is a good read though thanks for that, has some good tips on testing the ADD with 12V once you get it off.

 

1st thing is clean electrical connections and add dielectric grease on outside.
Sounds like the Tcase switch that activates diff actuator is suspect.
I know you have the non button Jshift manual but there are still switches and selnoids even without the button.

 

Gotcha, forgot to mention I found a little breather hose on top of the transfer case unplugged about a week ago. Probably unrelated but maybe some dirt worked its way in there, fixed it w tape temporarily. I'll add those to the list of things to do.