99 5.7L Tahoe - No rear wheel drive in 2wd or 4wd

[MarkP]

My plow truck has been working OK for 195,000 miles on it, but I've been hearing a popping noise from under the vehicle, likely transfer case, for a few weeks now. Everything else has been working OK with 4WD. Last night the RWD stopped working in 4WD and if I switch into 2WD the rear wheels don't drive the vehicle and it rolls in park. If in 4WD it will stay if in park, but when in drive only front wheels are driving. I also had a situation the other day when I was driving slow that the vehicle stopped ******* its own like I put it in park. I reversed and after about twenty feet it stopped hard again like I backed into something, but I didn't. The transmission was replaced within the last two years and has very few miles on it since then. I'd greatly appreciate any input. Thank you!

 

[Big Mama]

Have you been under it to see anything obvious? If I understand your post right the vehicle stays put in neutral in 4wd and drives in 4wd but nothing in 2wd? Easiest check is the rear end. Put it in 2wd in park and jack up the back enough to see if you can spin the wheels by hand.

 

[MarkP]

Thanks for your response! I've checked under the vehicle and nothing glaring. So if I have it in park while in 4wd is stays put. If in park while in 2wd it rolls. Only the front diff is working, so in 2wd it won't move in drive and in 4wd only the fronts are driving. The popping makes me think the transfer case chain is broken or off and hitting inside the case. I'll keep digging.

 

[Lancem]

Jack up the rearend on one side and turn the lifted wheel, if it turns and the driveshaft turns the transfer case is bad, if it turns and the driveshaft doesn't turn the rearend it bad.

 

[MarkP]

Thanks. It's rear diff.

 

[bigfootchiro]

Thanks. It's rear diff.

Exactly what I was going to say

 

[Big Mama]

That’s much better than trx case. How are you going to fix it? Rebuild?

 

[MarkP]

I took it to a local shop. I'm good with some things, but don't want to mess around with this. I live in western NY and the less time the plow truck is out of service the better. It'll be $300 to get it going down the road.