4WD hi light blinking all the time

So an update on the 2002 new to me tundra TRD limited, when test driving I tested the 4WD and the whole time the 4hi light is blinking, we put it into 4wd, you can feel it engage. And works no issue, still blinking though. Take it back out of 4hi no issue after depressing the 4hi and engaging 2wd, still blinking, after searching the forums it’s to my thought the front actuator contacts are possibly dirty and not making good contact on either side? Since it still engages and disengages. Didn’t actually see this problem on the forums so here we are making a post… thanks everyone I also haven’t had the chance to look at anything else after buying, went straight on vacation after buying it. Will be back Tuesday for updates

 

Sounds like it's stuck in 4Hi so likely stiff when turning if on pavement (and not good for it). Usually backing up while trying to disengage can get it to pop out of 4Hi back to 2H.

 

I'd start here, reply #11. https://www.tundras.com/threads/4wd-issues.119382/#post-3081795

Sounds like you may've already found said video, but ... tossing it out there.

Flashing, IIRC from the manual, means the 4WD ECU believes 4WD is not engaging. If it's engaging 4WD fine, but the ECU doesn't sense it, logic would dictate one of two things is an issue: (A) Whatever is responsible for telling the ECU "I shifted into gear!" is not reporting back to ECU properly or (B) 4WD ECU isn't interpreting what it's being fed and may be defective. But this is just a wild stab in the dark, punching wet paper bags underwater.

 

I can definitely say it’s not stuck in 4hi. Something electrical thinks it is though.

Yes good point. I’d hope it’s just dirty contacts and not the 4wd ECU. I’d imagine that can’t be cheap. Unless I get it from a junkyard or something but even then, it’s been sitting for god knows how long if I go that route

 

I think the last person I saw on here that said they needed to order one picked up at JY for pretty cheap, fleaBay for $50-60. I see there's at least one - I cannot guarantee part fitment on this - but there's at least one for ''00-04 for $80 on fleaBay now, but only one left. https://www.ebay.com/itm/116098491128

 

Oh that’s not bad at all. Even if it was a little more not bad. I thought it would be way more, I’ll have to dig into it on Tuesday and take off the actuator cover and take some voltage drops when switching it, and if that turns out to be good maybe order one just in case and return it if mine is good. Appreciate the advice!

 

There are two actuators necessary to engage 4WD. The transfer case actuator is responsible for engaging the front drive shaft, and also 4LO. The front diff has an actuator that engages the front hubs (remember when you had to hop out of the truck and turn the front hubs to engage them?).

1. It's possible that the transfer case is engaging/disengaging correctly, but the front actuator is not disengaging. While you're in a state where you believe you're in 2WD, lift the front end and spin the drive shaft by hand. What happens? It should spin freely. Now spin the front wheels by hand. What happens? They should spin freely as well. Now shift into the state that you believe is 4WD. Repeat.

2. The Transfer case actuator has two switches which which trigger off a detent on the actuator shaft, telling the ECU whether the transfer case is in 2WD, 4HI, or 4LO. Check these switches. If one or both read wrong, than either the switch(es) are bad, or the actuator rod is not clocked properly.

3. If you're still trouble shooting after this then refer to the video