Electric shift transfer case 1999 2500 Sub

[Yukon6.2]

Hi All
Has anyone had much to do with the electric shifter on the tcase ?
I thought my sub had a actuator issue on the front diff,so while i had it in my shop for a few other issues i decided to fix the 4x4 as well
Put it up on the hoist to see if the front would engage.So far it would never shift into 4x4
Got it to shift into 4x4 and the front wheels were turning,Yea...
Ya it was short lived,next thing it was stuck in neutral.
Took the skid plate off and could see duct tape on the shifter motor.Removed the assembly which seems to function.Fixed the cover for the motor will add a little synthetic grease to the gears and try it again.

[DmaxMaverick]

Duct tape is a pretty good first indicator. Very handy, but temporary fixes often become forgotten, or passed on to someone else. Is the 99 a GMT 400 or 800? Does it have a DIC (Driver Information Center)? Is the "Service 4x4" displaying, if so? I'm sure it's a GMT-400, being a tooling transition period, but stranger things have happened. The first suspect is usually the switch module in the dash, but the duct tape suggests you're not the first to visit this problem.

[Yukon6.2]

I haven't seen any sign of the DIC in the Burb
Yesterday kept me away from the Burb
Was working on my Feller Buncher with a welder to get the head apart for repairs,then moved a couple containers and a dead tracker.As i was unloading the tracker the main hydrolic hose on the truck decided to let loose.

[Yukon6.2]

Sifter motor back together and installed
I tried to get it to shift in the shop and it doesn't shift as good as i would think it should.
But i have never had a electric shift GM of this vintage.
What is the correct procedure to shift the tcase on the 400 trucks?
Thanks

[Robyn]

Place the tranny in Neutral.
Press the desired range button .....The indicator lamp should blink and then stay lit when the range selection is complete.

The Auto 4x4 is 4x4 high only and uses an electric clutch pack that is controlled using the ABS and other speed sensors to know when there is a disparity of speed between the front and rear wheels.....The system is annoying....ON/OFF.....ON/OFF ......It will stay off on dry pavement....but in a tight turn may bump...bump...bump.....You can feel it in the steering.

My opinion is that the Auto is worthless and just more goodies to fail.......


Best system on a GMT400 was the floor shifter with a cable actuator added to control the front axle.

Front hubs....Little Johnson bar on the floor.....Pretty much as close to perfect as one can get.

Electrical connections can and do fail....Along with control modules......Water, salt and other things.....Ice ripping wires off....can and do cause total failures.


People just got lazy.....Too much trouble to get out and turn in the hubs.......Or.....The hubs look stupid sticking out.....They want a clean smooth look......And comes the failures...

Weather turns ugly.....Heading into the bush....FLIP IN THE HUBS and leave them in.....

So simple.....

[Yukon6.2]

Yea i have no love for modern computers,modals, or wiring.
It seems very hesitant to change gears, the reason for asking.
This is my first unit that i have kept with the push button tcase
Picked up another straight body crewcab with a leaver case,no rust on the cab
My 52 Chebby has 8 wires under the dash

[Robyn]

Yeah.....And the 52 will still work with 6 of those wires cut.....Simple is a good thing...
With the Tranny in Neutral....and the engine running the shifts between 2H and 4H should only take about 3 seconds or so.....Same on the other shifts.

If you do put the T case in Neutral.....Going back into 2H or 4H can be noisy as the input shaft will start to spin up.....

Shifting on the fly is quite fine....Just shift the tranny to N and press the button.... ONCE THE 4H LIGHT COMES ON....SHIFT THE TRANNY BACK INTO GEAR *****DO NOT shift to 4 LOW on the move......NO NO... Full stop and tranny in N then select 4L*****

After being in 4x4 FOR A TIME....to shift out....Stop.....back up a few feet (15/20) then shift to 2H ...This will free up the drive train and allow the shift to complete much more reliably....Easier on the shift fork wear pads.. Always get tranny to N when shifting....

I would say if the shift motor is not working within the times described....A fresh shift motor is in order.....Far better to deal with this issue in decent weather.....Get all the wiring neat and tidy too...Tucked up away from road debris and such....Connections all cleaned with cleaner and dielectric grease added to the plug connections.....Zip ties are always a good thing to get stuff secured..

The headlong rush to put electronic control modules on everything has come to a fever pitch.....

The family grocery getter .....Well they may be a little less susceptible to physical failures of the electronics due to tough operating conditions....But a well put up "Rig" needs to be as "BOMB PROOF" as possible.....

The military uses a lot of real sophisticated equipment .....But I always laughed at the fact that the civilian version of the HMMWV had to have the Electronic injection and crap that was/is prone to failure....
The mil stuff was/is bare bones gitterdone and bring the crew home safe.....Unless they hit a IED that blows off half the rig.....

A little story from back a few years.

I had purchased a 1991 K1500 Burb....Lovely rig.....Low miles and just immaculate.

We had a snow event that started one afternoon....We headed home and the roads are getting snotty even in town.

We stop for groceries ...while the rest of the family is in the store I decided to twist in hubs while we were in a safe place....We would need the 4x4 for sure getting home.

While I am out twisting the hubs a young fella is watching me intently and just had to come ask WHATCHA DOING ???

I explained ....I got the deer in the headlights look ......

He starts in on an in depth explanation of his ABS, traction control and yada yada yada in his late model SUV.....

I smiled at the young fella...."Yeah...Right...UH HUH" and crawled back in the Burb

Family shows up...we load the groceries and head up the mountain.....

We get to the first tough spot and here is the little SUV upside down in the bar ditch....and a whole batch of other rigs all tied in a knot......

The Burb crawled through the mess and did a magnificent job.....Simple operation.....No need for any failure prone parts to get in the way......

The little SUV was in that Bar ditch for a couple weeks before somebody dragged it out......
I do not know the exact circumstances as to how it got upside down.....

Driver error was probably the vast majority of the issue.. And believing all the BS in TV ads that show the happy HOOOOOMANS scooting along through the deep white fluffy stuff in their SUV......

Some many old tricks (Pitch it and gas it) will not work with the newer rigs...The electronic controls keep you from doing things that work well.....

Our 05 Burb has the same push button 4x4 yours has.....Turning off the Traction control helps a lot.....Trying to get wheel speed up fast enough to get through the tough stuff is impossible when the traction control is ON

It just turns off the throttle (Electronic) when it senses wheel slip......ARRRRRRGH

Laziness on the part of people....."What are people going to think if I have to get out and turn something to have 4x4 ???? " I laugh at these notions.

IF the electric shift motor works AND all the modules and such do what they are supposed to....The system works.... BUTTTTTTTT One wire gets chaffed....one magic box dies and you are fouled.... And no way to manually get it going to get home...

Hubs rarely if ever fail......Hard usage can break them....I have never broken one....The auto hubs.....NOT SO MUCH....FAILURE PRONE ITEM.....Warn hubs...yessssssssssss....Or similar

Living in a very unforgiving place like you do.....I would prefer all mechanical.....Sleep better at night too....