4x4 will not engage

[tylerfm]

After reading MANY posts, I couldn't find one exactly like this problem I'm having...

My TB will not engage into 4WD at all. :hissy:

When in a crawl (about 5 MPH) I'll move the selector from 2WD to 4HI. I can hear the motor try to engage and sounds like it should. (low groan and slight clunk - or at least that's how it's always been with me) Then when I do the test of small circles on gravel I do not have any wheel jerk/slippage coming from the front end. It just acts like it's still in 2WD mode. Next test was on an incline. Putting the nose towards the top of the hill, and accelerating on loose gravel. Full rear wheel slippage with no action from the front.

Move selector from 4HI to 2WD. Vehicle into Neutral. Selector from 2WD to 4LO. Again the same sounds from the transfer case/differential (sounds like the actuator is working...). Again the same tests. No front wheel slippage at all, but total slippage from the rears.

On all tests, the indicator lights do their thing as they should above the selector knob.

No loud banging or anything.

I use my 4WD often (about 3 or 4 times a month) and haven't had this problem before.

Any help would be appreciated.

[BUC NASTY]

you have to reprogramm your transfer case. Mine has been fine ever since then.

[the roadie]

The front axle actuator is also a high failure rate item. Its noise is a lot higher-pitched whine. If you only hear noises from the transfer case area and nothe passenger side of the front axle, you could have a bad acutator, wires, or control module. Listen to another TB with 4WD and see if yours sounds the same.

[Tiny1877]

My '05 doesn't make any loud noises, just a light *thud* when it clicks in. If the actuators ever go back, I'll fix them once and then start looking for a vehicle with REAL 4wd (I prefer a shifter on the floor, not this ****ty push-button junk with expensive actuators) and move on. This was the 1 thing about the TB that made me nervous about buying it (aside from the bow tie in the grille; I'm a dodge man at heart).

[Envoyguy05]

another cause might be the encoder motor on the side transfer case

[wardak33]

another cause might be the encoder motor on the side transfer case

that's what i was thinking...

[tylerfm]

Firstly, thank you all thus far for your responses.

The front axle actuator is also a high failure rate item. Its noise is a lot higher-pitched whine. If you only hear noises from the transfer case area and nothe passenger side of the front axle, you could have a bad acutator, wires, or control module. Listen to another TB with 4WD and see if yours sounds the same.

Is there a way to test to see if the actuator is the culprit? The sounds seem to be very similar to another TB... What wires would I be looking for? Control module? Is this the guy located in the cabin by the drivers knee?

another cause might be the encoder motor on the side transfer case

What's an encoder motor? I haven't heard of this before...

[tylerfm]

*bump* ^
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[the roadie]

Yes, the control module is by the driver's knee. Trade with another TB if you can. Remove the actuator from the passenger's side of the oil pan, and see if it makes a whine when it goes in and out. Get a Haynes manual to show you where everything is, since the factory manual has too many pages to scan. The encoder motor is how the transfer case does its mode changing. Again, if you really want to dig into it, you need a manual. It's a bit complex to explain it all here. The front axle actuator may be good, but the internal splined disconnect may be broken. You may need a professional shop. Sorry.

[tylerfm]

The front axle actuator is also a high failure rate item. Its noise is a lot higher-pitched whine. If you only hear noises from the transfer case area and nothe passenger side of the front axle, you could have a bad acutator, wires, or control module. Listen to another TB with 4WD and see if yours sounds the same.

Well, I finally broke down and took it to a shop. Turns out that your original prognosis was correct. I'm going to need a new front axle actuator - the original one that I thought sounded like it was working was only moving just slightly and would not engage fully.
They said $250 for the part. Does this sound like a reasonable price? At any rate, they had to order in the actuator from Vancouver and will have it shipped by air tomorrow morning. So I've got another date set up for Monday morning.

[the roadie]

Sorry. $60 US on Ebay. And that exact failure is one like I fixed for free on Teebes' truck and posted about here with pics. But it helps to be an EE.

[tylerfm]

Sorry. $60 US on Ebay. And that exact failure is one like I fixed for free on Teebes' truck and posted about here with pics. But it helps to be an EE.

Lol... Also helps when there isn't a foot of snow on the ground and -20*C outside. And when you have a shop to work in...
But I guess that I'll at least have the old one to tinker with when the new one is installed, and then I can use your post to guide me through fixing and give me a trail spare.

BTW, what's an ''EE''?

[the roadie]

Electrical Engineer. We work on the microscopic parts of cars. Mechanical Engineers work on the bigger parts. Chemical Engineers work on the fuels. Civil Engineers sell cars. And History majors ask the people who own cars: "Do you want fries with that?"

[Robert1101]

Electrical Engineer. We work on the microscopic parts of cars. Mechanical Engineers work on the bigger parts. Chemical Engineers work on the fuels. Civil Engineers sell cars. And History majors ask the people who own cars: "Do you want fries with that?"

LMSO!!!! Well worded!!!!
:rotfl: :rotfl: :rotfl:

[tylerfm]

Well, it's not the actuator either. The shop I took it to did a little wrenching today and had a look at the actual system after they tried to install the actuator that they ordered. Turns out that it's actually the axle disconnect (mainly the fork apparently). So we tested my original actuator off of the vehicle and it spun freely... That means I will no longer have to pay $250 for a part that I could have got off of ebay for $70. Not a bad break I suppose. About an hour more shop time for the dismantling of my TB, but worth it I think. We'll see if replacing the Fork will do the trick. I find out next Monday.

[q65js]

Hey tylerfm , I'm very curious to hear the outcome. It sounds like I've got the exact same problem , I traced it down to the front actuator and when I tried it after unbolting from the axle housing it worked as well so I'm figuring either the shift fork or the coupler that the fork slides to join the axle halves together. Keep us posted.

[tylerfm]

Hey tylerfm , I'm very curious to hear the outcome. It sounds like I've got the exact same problem , I traced it down to the front actuator and when I tried it after unbolting from the axle housing it worked as well so I'm figuring either the shift fork or the coupler that the fork slides to join the axle halves together. Keep us posted.

Yeah, very technical system... I'll let you know how it turns out.

[tylerfm]

Well, as promised, here's my post. My TB is all fixed up and ready again to wheel... in the snow. :(

Anyways, the shop ended up changing out a few parts. A little more than I expected to be honest. They put in a new Fork, gear, couple seals, bearings, and an axle assembly.

The fork, gear, seals, and bearings are pretty self explanatory. The axle assembly was the part I wasn't expecting to replace. Turns out that the way the fork etc broke, it was wearing away at the axle - so there was a nice groove worn into it... A $1400 part from GM. Luckily I was able to salvage one for $175 from their wrecking yard.

Works like a charm again. :woot:

Also salvaged from the wrecked TB in their yard was a compass/temp mirror! Sadly I don't have the 16 pin connector to hook it up plug and play, but that'll be another post.