Flashing 4wd light

Hi guys first post and I need some help, wore out the search key but still haven't figured it out.

2012 AC cab V6 4wd. Truck is in perfect condition 15k miles . I lifted it with Ome kit and 33s . I wanted to regear and had a shop install 4.56s with a rear Trutrac . I picked it up from the shop and went to leave and 4wd light was flashing and won't shift into 4WD. I have had it back in the shop for 3 days and they can't figure it out and even installed a new actuator. I have checked all the fuses and connection including the vacuum lines , disconnected the battery etc and can't find anything wrong. I have an appointment next Tuesday at the dealership but wanted to see if anyone had any suggestions. The 4WD worked perfectly before the regear.

Thanks Tim

 

I have a 2005 but try shifting into neutral and slowing down or completely stopping before turning your knob from H2 to H4. You may have already tried that though

 

Check the wheel speed sensors?

 

How do I do that?

 

It is the green stick picture of the truck wheels in the bottom of the speedo blinking green

 

It is what the shop changed and still didn't fix it .

 

Jack up the truck and see whats spinning when you shift into 4wd. Then report back.

 

Only the rear , if I put in park with engine off switch it to 4 hi then start it I can here some actuator noise on the T-case but the thing won't engage 4wd

 

Is the front driveshaft spinning or no?

 

Yes

 

Then whoever installed you ADD actuator put a bad one in or didn't connect it right.

 

That's what I don't get brand new factory ADD , all connections are good

 

They are known to be junk, I'd take the actuator off and see if the fork is moving, also make sure whoever put the actuator on installed the fork on the clutch hub in the stub tube if not the 4wd will never engage.

 

I looked at the fork and it slides freely but can't get the Add to do anything. Hooked it up to a vacuum pump and couldn't make the old one budge . Guess I will see what the dealers says Tuesday, thanks everyone for the tips , appreciated

 

On a brighter note liking the 255/85/16 - 4.56 combo

 

Hooking it up to a vacuum won't do anything it is electronic. Hope you get it figured out.

 

Ok thx

 

Up date , dealer installed new ADD and said the had to re flash ecu . Working now . Dealer was great about getting it fixed under warranty.

 

Sounds about right , but they put it on the paper work