Doc16743

Had the L6 engine in my '07 TB replaced last summer when the original ate a valve. Since it was summer there was no real way to test the 4WD (we're a senior couple - no off-roading!). First serious snowfall this year we found that 4WD doesn't work. The indicator lights on the dash control act as they should (flash several times with mode change, then stay lit). The transfer case seems fine, as low range works, but the front axles apparently aren't engaging.

My mechanic verifies this, but doesn't have a clue why it doesn't work. Bear in mind that this is the same guy who replaced the engine - successfully, I thought - and is not a Chevy trained technician. He also replaced both front wheel bearings a couple of months ago. I suspect during one of these repair jobs he disconnected or forgot to hook something up. Mechanic states that the transfer case is indeed getting the proper voltages from the control switch and is activating the front drive shaft, but the front axle does not get a voltage change and remains disengaged.

I know I can take it to a Chevy dealer, but that is both inconvenient where we live (very rural) and very expensive!

Can anyone give me an idea where he should look? I realize that diagnosing a car remotely is very difficult, but perhaps someone has had a similar problem??

Thanks!
Doc

oilcanhenry

Did anyone check the FWD accutator itself ?

Doc16743

Thanks for the reply!

If the actuator is the device that causes the front axles to engage, the mechanic said he checked it and that it dot appear to be getting any voltage. He identified a four-wire plug attached to it. He identified the ground wire, but said he does not know what voltages are supposed to be present on the other three.

Thanks!
Doc

oilcanhenry

You almost certainly have a bad FWD acuatator, IMO.

Doc16743

Have an appointment for Tuesday morning for him to check the actuator. He did speak to a tech at a local Chevy dealer, and they also told him that was the likely source of the problem.

More when I find out Tuesday!

Thanks
Doc

oilcanhenry

Lets us know what happened.!

Doc16743

Mechanic pulled the actuator. The moving shaft was loose and sloppy as well as being easy to push in with light pressure. Have an appointment for Tuesday to replace it. At the same time he's going to check the fork, to be sure it's moving properly. The slack in the actuator sure makes it look like that's the problem! More Tuesday!

Thanks
Doc

oilcanhenry

Glad you found the problem, Doc!

Doc16743

Feel like I have the starring role in "The Never Ending Story"! Now the mechanic tells me it's the fork causing the problem. He has it ordered and should have it today or tomorrow.

What disturbs me is that he had the whole front end apart to replace the engine. I have no way to tell if he caused the damage to the fork or if it was just wear (it is 12 years old). With that as our only vehicle I'm pretty well stuck until he brings it back. He offered to let me drive it until the part gets in, but we have 6 inches of ice & snow in the driveway, and it'll never make it in two wheel drive.

Stay tuned for the next episode of "As The Trailblazer Turns"!!

doc

Doc16743

Finally!!! Just got the TB back with 4WD actually working! Mechanic replaced the fork and it seems to work fine. He said one side of the fork had snapped right off.The one thing concerning me now is that he says the "hub" (drum?) the fork pushes into seems to be quite worn (107K miles). He said rather than buying a new one for $200+, he made a shim. I haven't seen a parts diagram of the unit, so that's the best I can do as an explanation.

As much as I like this vehicle, I'm beginning to be turned of by it. My $4500 used TB now has me into it for an additional $1800 for replacement engine and so on. Just as a side note, it was apparently involved in some type of wreck, although nothing showed up on Carfax. The right taillights were not fixed correctly and the entire light housing sticks out at least an inch farther than the left side. Also, the rear wiper has never worked, although the dealer did make an honest attempt to repair it. Also only one side of the stereo system works - no sound out of the right side. Little things that don't get noticed on the test drive!

It's mine, warts and all, and hopefully it's not going to continue to bleed me dry!

Thanks all!!
Doc