4Hi flashing with a twist.

I recently purchased an 01 Tundra and when I got it home I noticed the 4hi button was flashing. Contacted the person I got it from and he said just pop it in neutral then drive a few times and it should work. So I did this and the light still flashes.

The vehicle came with another set of wheels and tires and I noticed that they were mismatched on the truck. I get to looking and the fronts are 265/65/17 and the rears are 265/75/17 which is a little over an inch in dia. difference.

I currently have the same size all the way around (265/75/17) and the light is still blinking. I figured I would come ask before I just start throwing money at it for no reason. Any ideas on what to do or check first would be greatly appreciated.

 

Mr Creosote? (sorry, i had to ask)

The actuator on 4wd high isn’t engaging. You may have to open it up and clean out the crud and corrosion. It’s usually do to lack of use.

Or you could continue to try to re-engage it every so often hoping it’ll start to work again.

 

So I was going to do this tonight. But I didn't know if the tires being different sizes and trying to engage while being at different ratios would would mess anything up first.

And that's the exact reason I stay away from after dinner mints!

 

If they’re close and you’re on gravel or loose dirt it shouldn’t matter for a small distance. If the tires can slip, your fine.

Driving longer distances, you may be concerned. I can’t remember offhand what’s allowed. If I had to guess it’d be something between 3/32-6/32s I believe.

I wrote it down once but I can’t recall.

 

I'm not sure how long the previous owner drove with the 4hi button engaged. If I press the button I can hear stuff trying to move. I'll clean out that actuator tonight and see if it does anything.

 

Yup, or snow. I'd get somewhere loose, where you have ample room to roll in a straight line 100ft fwd, 100ft in reverse, press 4HI button while slowly rolling fwd, if nothing, repeat in reverse.

Does the light just flash all-the-damn-time? Like, it's flashing when you start the truck, before it goes in gear? Any beeps heard when you try to put it in 4HI?

Did you check all the wiring to the front diff to make sure it's intact?

Sometimes folks find tapping the actuator will kick it into acting right. Sometimes people with similar issues to yours find the 4WD ECU (separate from regular ECU) is fried. This is an issue you can end up throwing lots of money at, seems like every part is $500+.

FYI: 4LO only engages if 4HI is engaged, and you're in neutral. Stupid observation, but you'd be surprised how many people think they can just kick 4LO on while rolling down the road.

 

I don't hear any beeping sounds. Like a door chime? If you push the 4hi button it just flashes until I turn it off. I turned it on after I got some new tires put on and took like a 20 mile trip around town and it just flashed the entire time.

 

The times when I've heard it are usually when I'm trying to engage 4HI while over-speed (55mph+), I heard three or four 1 sec beeps. The beeping is just another built-in diagnostic.

The flashing is the very generic indicator for "not engaged yet". There's a lot of info 4WD, the needs (recommended to engage ~10mi per month), etc. in the Owner's Manual. I know not a lot of people read it, and it probably wouldn't help you in this case, but if you're new to the truck and generation of Tundra, you may want to check it for referential purpose.

There are a couple of really good threads on this issue in the 1st Gen forum. I'll link them for you.

First thing to do is to check the '4WD' fuse in the dash, make sure it's not blown, or just proactively replace it - it's clearly marked.

Check your actuator, the traces inside the cap, for corrosion: https://www.tundras.com/threads/4hi-light-keeps-blinking.34888/

Some people will whack the cap before taking it off, and put a hand on it to see if it clicks while engaging: https://www.tundras.com/threads/sol...-wont-disengage-4hi-and-4low-work-fine.32495/

Some more advanced diagnostics in the video linked here: https://www.tundras.com/threads/4-wheel-drive-stuck-in-4hi-and-flashing.88628/

 

Thank you so much for the help. I'll grab some electric parts cleaner and grease on my way home.

 

Wether its your problem or not....fix that tire mismatch ASAP. Thats outrageous on a 4WD vehicle.

With that tire difference, in 4wd, its like driving 30 miles, then locking your rear wheels and dragging them for two miles and then doing it again. I'm not surprised the 4WD isn't working if the previous owner was abusing it like that.

 

Yeah that's what I was mostly getting at with this post. If it would destroy other internal parts or just start with the basics and go from there. Either way it's an 01 and could probably use some PMCS