Rarely drive in 4wd but do it every few months just to keep things moving.
But pretty much always in 2wd. Had been getting an intermittent Service 4wd light while driving in 2wd. Last time I did that it was just the switch in the dash.
So bought a new switch installed it and went rolling in 2wd drive with no issue. Figured I would run it through the gamut to be sure the switch worked.
Started with 4 hi and went in and engaged no issues.
Stopped put her in neutral to go back to 2wd. 2wd flashed for a bit and then the switch clicked and back to a solid 4 hi.
Tried 4 low and 4wd Auto all with the same issue.

Switched back to the old switch and same results.

I hit the switch and I can hear an electronic buzz under the truck for the duration of the time the light is flashing on the switch while trying to disengage.
The buzzing stops the switch clicks twice and goes back to solid 4 hi.

Is there some sort of electronic solenoid or relay that is not working or are my issues larger?

In a Ford, there is a motor on the transmission that mechanically moves the interior gearing between the various options, as indicated by the dash switch.

My 2010 failed, but fortunately, it failed in 2wd, not the alternative.

My suspicion is that you have a similar problem with either the motor failed, or the shifting linkage failed.

There are two things to consider to make it drivable on dry roads without further damage; one is to give the shift motor a couple of quick raps with a mallet, to see if you can free it up to shift back into 2wd, the other is to see if you can pull the vacuum hoses that lock the front hubs, so that you can ensure that although the front axle is turning, the hubs aren't locked, and thus aren't stressing the rest of your drivetrain on dry pavement. Be careful with the "unlock the front hubs" thing though, some vehicles use vacuum to keep the hubs from locking, so that if vacuum fails, the hubs automatically lock, some use vacuum to actively lock the hubs. My understanding is that Ford uses vacuum to keep the hubs unlocked, and that if the hoses fail, the hubs will automatically lock, so that when 4wd is engaged, it still works. YMMV. It is possible, that if you set it to 2wd, you will unlock the hubs, but still have the transmission turning the front drive train, and could drive it to the mechnic/dealer without damage. I would test this theory before trying it, however.

If you can't solve the problem with either of those methods, (or the suggestions of other more Chevy knowledgeable guys here) I'd have it towed on a flatbed to the mechanic/dealer, rather than risk additional damage with dry road 4wd.

My O5 Tahoe had a similar issue, and it was the motor that controls the selector at the transfer case.

It was about a $600.00 repair (parts and labor).

Ditto on the two previous comments. Mine stuck in 4 Low and I was in the middle of nowhere. Took two days but I made it to a garage for the fix. You can try a redneck fix by rapping the motor in the tranny with a hammer. If that doesn't work you need to get it to a repair shop.

Thanks fellas. Looks like a simple job but a couple hundred bucks for the part. I presume the process is pretty much identical between the Silverado and Suburban.




Link to original video: https://www.youtube.com/watch?v=8Zow_YX69LE

I had to replace one on a AWD Buick Rainier. It wasn’t hard at all.

Try this is cost nothing only your few minutes of trying. Park on a flat surface, put transmission in neutral. Then see if it will go in. I have had it happen from pickup trucks to All wheel drive 80,000lbs. concrete trucks. If it doesn't work at least you tried it. My pickup is sometimes a pain to get out of hi and low.

Transfer case shift motor...Has 3 bolts holding it in, if I recall correctly. Easy swap out.

quote:

Originally posted by ChasinTails:
Transfer case shift motor...Has 3 bolts holding it in, if I recall correctly. Easy swap out.

Or it can be the indicator switch or a internal transfer case problem.

quote:

Try this is cost nothing only your few minutes of trying. Park on a flat surface, put transmission in neutral. Then see if it will go in. I have had it happen from pickup trucks to All wheel drive 80,000lbs. concrete trucks. If it doesn't work at least you tried it. My pickup is sometimes a pain to get out of hi and low.

Also try just driving back and forth in a strait line, sometimes the transfer case gets bound up and can't move the gears with the electric motor. Basically the front axle binding with the rear axle.

With our tractors, when they get stuck, the trick is to back up in a straight line, put them in neutral, then try to release 4wd as it coasts to a stop. You might try that with your Suburban as well. As others have noted, sometimes there's too much strain on the drivetrain to shift it, particularly if the shift motor is giving out.

quote:

The buzzing stops the switch clicks twice and goes back to solid 4 hi.

I smell a transfer case encoder motor. (Yes, that's what they call it.) The clicking and buzzing tells me the circuit works and the motor is trying to work, but the gear train inside is stripped. It's a pretty common problem. Assuming there is no internal transfer case problem ...

"Stopped put her in neutral to go back to 2wd"

Why did you stop and go to neutral to shift? Going between 2 and 4hi should be done at moderate speed and without shifting the transmission to neutral. Just let off the gas, hit the switch and then depress the gas and continue. Shifting to 4low should be done in neutral with the car rolling under 4 miles per hour, not at a full stop.

I had a 1997 Silverado that would shift into to 4 hi just fine but would not shift back to 2wh unless I stopped and shut the motor off then restart it.
Long story short, tires.
Front tires were fairly new and rear tires were wore down 50/60%.
Shop manager took tires off his truck (all 4 equal in wear) and put them on my truck and told to try it out.
Shifted in/out of 4wh hi just like new.
Bought new tires, same brand as frt, and was just fine.
Shop manger said they see it a lot.

Make sure your tires circumference measurement are as close as possible. It makes a difference.

quote:

Originally posted by egregore:

quote:

The buzzing stops the switch clicks twice and goes back to solid 4 hi.

I smell a transfer case encoder motor. (Yes, that's what they call it.) The clicking and buzzing tells me the circuit works and the motor is trying to work, but the gear train inside is stripped. It's a pretty common problem. Assuming there is no internal transfer case problem ...

X2 on the Encoder Motor being bad. We always stocked a bunch of those.

GM guys, if a transfer case goes bad definitely look into a GM Powertrain Remanufactured one. 3 year/100,000 mile warranty and if the old one is physically damaged ask to make sure but they used to offer a "no hassle" core credit,as long as it was complete you were not "dinged" for a hole in the case from a chain failure, stuff like that. But if you returned it missing the encoder motor or any of the switches (all included on the rebuilt one) that is the only time you would get hit on your core charge.

quote:

Originally posted by gjgalligan:
I had a 1997 Silverado that would shift into to 4 hi just fine but would not shift back to 2wh unless I stopped and shut the motor off then restart it.
Long story short, tires.
Front tires were fairly new and rear tires were wore down 50/60%.
Shop manager took tires off his truck (all 4 equal in wear) and put them on my truck and told to try it out.
Shifted in/out of 4wh hi just like new.
Bought new tires, same brand as frt, and was just fine.
Shop manger said they see it a lot.

Make sure your tires circumference measurement are as close as possible. It makes a difference.

That happened with a Jeep Cherokee we once owned. At first I thought the dealership was pulling a fast one on my wife.

I bought a new diesel Silverado in 2002. I was so concerned about the transfer case pump rub that I bought a kit and had it installed to prevent that. The pump rub and leaked were not uncommon at the time.

quote:

Originally posted by TXJIM:
"Stopped put her in neutral to go back to 2wd"

Why did you stop and go to neutral to shift? Going between 2 and 4hi should be done at moderate speed and without shifting the transmission to neutral. Just let off the gas, hit the switch and then depress the gas and continue. Shifting to 4low should be done in neutral with the car rolling under 4 miles per hour, not at a full stop.

Guess, I’ll reread the manual in the morning.
I thought for sure switching in and out of 4 hi and low required going to neutral hence the buttons being below the neutral line on the switch and only 4 wheel auto did not need to go to neutral but had to be under 30mph.

Guess I need to rear up on my Expedition and make sure I am doing that one wrong too.

Almost three weeks. Did you find out anything?

Sorry the past few weeks any of my spare time has been dedicated to finding my wife a vehicle.
https://sigforum.com/eve/forums...0601935/m/7020094564

The Silverado is just a spare so it has been on the back burner. I picked up a new Transfer Case Motor from NAPA on Tuesday.
Whenever weather is acceptable for me to climb under and swap it out I will. Hopefully we’ll get a warm patch on my days off in the next few weeks.
I have had Coilovers and Upper Control Arms to put on the Expedition since Black Friday so has not been much good weather on my days off.