4WD blinks but won't engage, mechanic says it works fine

hello all, I have a 2008 toyota tacoma automatic transmission.
today my 4WD won't not successfully engage. I have used it a few times in the past few days. I would switch over the knob and the green icon would just blink incessantly. I tried moving while doing it, being still while doing it, shifting into neutral, etc.

I took it to the dealer for them to run diagnostic tests. they gave me a call saying it works perfectly fine for them. What might cause this? I am in Minnesota with a lot of snow on the ground. can that effect the transition to 4WD if the tires get caked with muddy ice?

What should i suggest to the mechanic? I really want them to dig deeper and look closer but I don't know how to express this precisely.

Finally, is there anything wrong with turning the vehicle off while it is engaged in 4WD?

thanks for any insight!!
-Sam

 

You should be fine turning it off and back on in 4wd. The knob sets off a mechanical process that will stay in place until you turn the knob back to 2hi. I've done this plenty of times.

Check the underside of the drivers side sun visor - mine has a label on it explaining how to use the 4wd. Maybe there's a simple misunderstanding in how to operate it.

Finally, mine also does not always engage. It wants me to turn the wheels or move just right and even then sometimes it doesn't engage. Per the directions on that label, I put it in reverse and it slams the 4wd into place just about every time. Give it a shot and let us know if you get it!

 

Mine does this if I don't use it enough. The actuator in either the front diff or transfer case gets tight and won't lock in. I turn the switch back to 2wd, shut the truck off, restart and try again. Try tapping on the actuator with a wrench too. Corrosion is your culprit. Use it more.

 

If the light is blinking then the 4x4 isn't engaged. Your actuators are probably going bad.

https://www.tacomaworld.com/threads/how-to-trouble-shoot-4x4-actuator.263525/

 

thank you everyone for the insights. yall seem to agree with the mechanics assessment !

I just moved to minneapolis from atlanta, so the system will definitely be getting more regular usage from now on. I can't believe how poorly I understood my own vehicle up until this move! I will try and employ the tricks and advice here and see what happens. Also, the mechanic mentioned my front and back tires have very different tread depths. he said that can mess with the 4wd engaging. I am getting 4 brand new faulken wildpeaks put on soon so hopefully that helps!

 

My 2009 was kinda a pain to figure out at first. MT, so maybe different but what worked for me was, being in neutral and holding clutch while pushing and holding the knob. And it had to go in steps, from 2wd to 4hi, then 4hi to 4lo.

 

Welcome to TW!!

 

I'm no expert, but I sincerely doubt that is the issue. Tread depth can mess with fancy AWD systems, but the 4WD in your Tacoma is very simple and varying tread depth should not effect 4HI engagement.

Check that your actuators aren't getting stuck, and like @4WD FTW stated, throwing it in reverse and rolling a few inches has always worked on my '15 when it is getting finicky.

 

Follow info in post #4 above.
Try engaging several times to get the contacts in the front diff and xfer case to make contact.
Most Tacoma owners have to do this every so often so unless the flashing light does not then go out time to follow the steps above.

 

It likes to engage more easily when driveshaft and everything is under no load, so generally sitting still with straight wheels or ‘coasting’ with straight wheels. If you’re applying throttle or turning or doing anything that’s straining or loading the system it can be more finicky or engage roughly.

 

Coming from a manual transmission Jeep Wrangler to the automatic Tacoma, I like almost everything about the truck better, but I do miss the manual gear lever 4wd selector in the Jeep. More mechanical than electronic, no pause, you shift into 4hi, and it’s in 4hi. Done. That is...until the shitty plastic FCA bushing on the end of the actuator cable breaks and suddenly nothing works. Been there, got stuck. Got pulled out by a Toyota haha (FJ)