Truck won’t engage the rear differential lock. 3rd gen

As the subject says - I can’t get my rear diff to lock. Not my first time asking for help but I’m still at a loss. I know it needs to be in 4Lo and on a surface other than hard pavement to do it safely. I have tried following the owners manual to the letter numerous times (ie engage 4 hi, then 4 lo, then while in neutral, engage the rear locker) and the dash light just blinks while I sit there. Blinked for 10 mins straight before I called it.

I’ve also tried driving it around a bit at slow speeds, forward, reverse, flat ground, at an angle, through some turns, etc. Nada.

Dealer claims they got it engaged while it was in the air (and then wrote me a condescending “follow your owners manual” maintenance note, and billed me for a bunch of labor). Under normal circumstances though, can’t seem to get it to work. I haven’t ever really needed it but it would be nice to know it’s functioning if for no other reason than because I paid for it (but really I would like it to work on my off-road trips).

Anyone successfully troubleshoot? Rest of the off-road functions work like a charm. Just can’t seem to get the rear diff to join the club.

 

It's been awhile since I exercise the locker in my wife's truck but it seem to go in without much coaxing.
Forgive me for asking but are you sure the transfer case has made the shift to low range? I ask because my most recent exercise of my 2017 (no locker) it seem to take more than expected just to get it shift into low range.
I say try it yet again, sometimes after hitting the locker button it takes a little movement and time to engage, tiny bit forward/backward but it should go.
Best of luck.

 

Yeah I always drive a little after hitting low range to feel the gearing and make sure I’m fully in 4 lo before shifting back to neutral and then trying the locker. I’m very confident 4lo is dropping in no issue. Just can’t get that dash light to stop blinking when I hit the locker button.

 

No need for neutral after your certain it's in low, just push that locker button, let it creep forward a little, gas/goose it a little or even reverse gas/lil goose it should lock in.

 

I wish… Taking it down an easy hour long or so trail tomorrow. I shall try again while I’m there.

 

check the fuse? Great looking truck though

 

To get the diff lock to engage (after you are in 4lo) you have to be moving, preferrably in a slow turn or s turns.

As a first test step, I recommend putting truck in 4lo, in park with hand brake OFF, with ignition ON and rear diff locker engaged.
Then jack up just (1) rear tire just clear of the ground. Turn the wheel that is off the ground and i bet you will feel it lock within about 30 degrees of wheel motion.

After that works, then try it on the ground by turning

 

Turn back and forth while moving forward. The teeth need to align to lock.

 

Going to give this a try tomorrow and see what happens. Appreciate the directions.

 

This ^^^^

 

E lockers require there to be differential movement between rear wheels to engage. If you are sitting stationary in neutral or drive, it won't engage. In other words, you need to be moving and turning in 4lo to get the rear to lock up. Even if moving in straight line, it won't necessarily engage unless one of the wheels loses traction.

 

I’ve tried that a few times but maybe I’m not giving it enough time to lock. I’ve probably driven 200-300 yards on slow turns just idling without successfully locking.

 

Yeah. It’s sometimes takes longer than you think. The front wheels turn in a sharper arc than the rear wheels so it can take some distance for things to lock up. If you are actually stuck with one wheel spinning, this is not a problem.

 

Drove it in an s-pattern for long enough for the e locker to automatically stop trying to engage. Probably at least 3-4 mins of forward and backwards random turns, some really slow, some faster. It just gives up on its own after a while. Going to try getting one wheel in the air via a jack and seeing if I can lock it like that.

 

This isn't true. I literally just went out to my truck thats been parked in the drive way for 2 days. Started it put it in 4hi- N - 4LO and locked without moving anywhere. That being said it many cases you'll want some movement so everything is aligned but its not required as you say.

I use 4wd and my locker almost every time I use my truck, You dont need to be making a ton of S turns and maneuvers for it to engage. You should only need to move forward or backward a couple of feet at slow speed (like a crawl).

You need to engage the locker as part of periodic maintenance, the more it's used the better it works. Once you get it working, do it several times.

 

I’ve attempted to use it more or less every time I get off-road (along the same lines as using 4x4 roughly monthly per owners manual). Has never worked since I bought the truck new. If or when I do get it working though, it’ll definitely become part of the monthlyish cadence of using the off-road functions.

 

You need to jack up the truck and actually determine if it's locking or not. You may have an issue with the locked indicator switch and not the actual differential locking mechanism.