RumorsOFsurF
Full Access Member
I took my Yukon up to the local mountains to do a bit of shooting and playing, and I discovered that my four wheel drive isn't working. I've only had the rig a month. I thought these occurences were strange until I read about how the NP246 works. Apparently when in 4hi or 4lo, the clutches apply enough force to "lock" the front output, as opposed to a true geared lock.
Here's what happened...
I engaged 4Lo to climb a steep hill. It seemed the 4wd was working fine until I went back down. I downshifted to utilize the compression braking in first, and the rear tires began to drag and I was sliding down the hill. I stopped and tried to reverse, only to find that the front wasn't engaged. Once I got to the bottom I tried to climb a rock pile in forward gear and the front tires were pulling. When I tried to back up the hill in reverse I only had 2wd. I found this incredibly strange. I tried the 4wd later in the day and it didn't work at all.
The indicator light comes on, there's no "service 4wd" light, and no other warnings light up. Once I got home I jacked the rear diff off the ground and the front wheels wouldn't pull the vehicle in any mode. The front driveline isn't turning, so I know that the front diff disconnect isn't the culprit.
My only thought is that the clutches are worn out. Or perhaps the encoder has failed.
Fortunately I bought the extended warranty, which should cover this...I hope. I have a 1:00 appointment tomorrow at the local GMC dealer for service.
Any other ideas?
Here's what happened...
I engaged 4Lo to climb a steep hill. It seemed the 4wd was working fine until I went back down. I downshifted to utilize the compression braking in first, and the rear tires began to drag and I was sliding down the hill. I stopped and tried to reverse, only to find that the front wasn't engaged. Once I got to the bottom I tried to climb a rock pile in forward gear and the front tires were pulling. When I tried to back up the hill in reverse I only had 2wd. I found this incredibly strange. I tried the 4wd later in the day and it didn't work at all.
The indicator light comes on, there's no "service 4wd" light, and no other warnings light up. Once I got home I jacked the rear diff off the ground and the front wheels wouldn't pull the vehicle in any mode. The front driveline isn't turning, so I know that the front diff disconnect isn't the culprit.
My only thought is that the clutches are worn out. Or perhaps the encoder has failed.
Fortunately I bought the extended warranty, which should cover this...I hope. I have a 1:00 appointment tomorrow at the local GMC dealer for service.
Any other ideas?
