05 tundra stuck in 4WD-HELP!

recently while driving, my tundra completely shut down. After multiple diagnostics, tech found that the fuse box needed replacing. After replacement, car seems to start and stay running. Now, my dilemma is the truck is completely stuck in 4 WD. Truck was in 2WD when the issue happened but after replacing fuse box, it is now in 4WD(was always able to switch back and forth prior to breakdown). In my attempt to switch to 2WD, the lights keep flashing and 2WD will not engage. I'm being told that it could need a new actuator($4k)! There are no codes found..

Does anyone have any tips to switch back to 2WD? Your help will be much appreciated. Thanks, Jeff

BTW, I love my truck(spent about $4k in recent maintenance and repairs)

 

Which fusebox? Was it corroded due to a windshield seal leak? You'll have the same issue again if you don't fix the leak.

That number just isn't right, it's a little pricey but it's not that pricey. It most likely would just need the electrical contacts cleaned.

Do some searching on the site, there are many different 4wd threads. Make sure you do an advanced search and set it to 1st gen only.

 

Is it 4hi flashing or 4hi solid on the dash. Friendly reminder it won’t do it in park.


start the truck, put it in reverse or drive, switch to 2wd, roll a few feet and see if it’ll engage.

 

But is the truck actually in 4WD? Or just the light is on all the time?

 

This!

If the truck was actually in 4WD, it would be binding up like a motherfucker while @chije82 was turning at slow speeds on concrete (unless someone swapped the front diff with Sequoia or upgraded to Torsen or ...)

@chije82 I would be reviewing your wiring to the actuators, and potentially the position sensor the ECU uses to figure out where you're currently geared. @BroHon or @FiatRunner or @Jack McCarthy can say more, one of them had this issue IIRC, but brain fog is hot right now, I can't recall.

Also check the actuator cap, as its traces are responsible for kicking around. Here's what you don't want to find inside the actuator cap, because the vent hose busted or fell off: https://www.tundras.com/threads/4wd-diagnosis.132880/#post-3427304

One example of a busted vent hose, you can see it off the nipple completely.

4WD support info here: https://www.tundras.com/threads/4wd-issues.119382/#post-3081795

 

Truck is definitely in 4WD, light is solid on dash. front tires grab hard in slow turn. When I press 2WD button the buttons flash.

 

So, I apologize if this is redundant information- but it is very important to know.

There are two actuators that shift the truck into and out of 4WD. One of them is mounted to the transfer case, and this one connects/disconnects the front driveshaft. The other one is mounted on the front differential, known as the Automatic Disconnecting Differential. ADD for short. This actuator connects/disconnects the front wheels from the front diff.

When the truck is in 2WD, the front driveshaft should be free spinning, and the front wheels should spin independently of each other.

When the truck is in 4WD, the front driveshaft should be locked and unable to spin, and the front wheels should both turn when one is spun.

Testing to see if the driveshaft can turn and if the wheels can spin independently is the first step towards diagnosis. This can tell you if one, both, or neither of the actuators are working as they should. Your test should be done with both front wheels in the air.

It might also help to try driving around with the lights flashing for a few moments. On our trucks you can shift in/out of 4WD while moving, as long as you are driving in a straight line and under 55mph. I'd see if the truck stays in 4WD while the lights are blinking.

 

UPDATE: thank you all for the pointers! So had some time the other day to try some of the things mentioned (driving in dirt and just shifting the gear back and forth @
khooiii). Something seemed to work, before I knew it, it was back in 2WD. However, both 4WDhi and low lights continue to flash(buttons out).

 

Glad to hear that you're out of 4WD. Both 4HI and 4LO flashing usually means that the 4WD control computer is still confused. When I was working on my 4WD, both lights would flash if the transfer case actuator was unplugged. I would check to make sure the front driveshaft can freely spin when you're in 2WD.

I actually wrote up a big guide to diagnosing 4WD issues a few days ago. Here's the link: https://www.tundras.com/threads/1st-gen-4wd-issues-diagnosis-prevention-guide.149189/

 

Sounds like it was bound up and you just needed the tires to slip on loose gravel/dirt. Just like I suggested on TS.