4WD not engaging

[USA-1]

Replaced the Actuator and the front axle disconnect. Can hear the front actuator and the transfer case motor working. Can feel the front wheel engage by spinning will jacked up, and wife moving the switch to 4wd. The front driveshaft also spins the front wheels when in 4wd. Try and move the switch to 4lo and service 4wd light comes on with no light over 4lo, remains at 4wd. Move the ignition key to off and switch to 2wd then turn the key back on makes the motors work and the light go off. My guess is the transfer case clutches are worn.
After removing fuse #8 under hood will go to 4lo, still no front wheels.

 

[Playsinsnow]

Some Sunday reading


http://gmtnation.com/f79/4wd-not-working-step-inside-107/

 

[USA-1]

4WD not working? Step inside. I have read this and think it's the transfer case. Just looking for more info before doing the swap. Is their a certain transfer case that should be used? For example out of a 2005 EXT model.

 

[Playsinsnow]

IIRC all 4.2&5.3l GMT's use the same transfer case. If buying a used TC, I would look for an '07-09 if possible. Newer. Do you know if the transfer case fluid was exchanged with Autotrak2 at every 50k? Can be a problem if this is overlooked.

 

[USA-1]

The transfer case fluid was change at 73214.

 

[The_Roadie]

It's an NP226 transfer case. I think it was 2006 when the case was redesigned with a stronger bearing mount, but that mostly helps people who overuse the hateful A4WD mode.

You do remember that there's an interlock and you can't go into or out of 4LO mode unless the shift lever's in neutral?

 

[USA-1]

It's an NP226 transfer case. I think it was 2006 when the case was redesigned with a stronger bearing mount, but that mostly helps people who overuse the hateful A4WD mode.

You do remember that there's an interlock and you can't go into or out of 4LO mode unless the shift lever's in neutral?

Yes, the shifter needs to be in neutral and I prefer stopped. Just upset at myself for repairing the wrong part.

 

[USA-1]

The option code NP4 and NP8 represent what?

 

[The_Roadie]

NP4 is the RPO code (glove box sticker) for the NP126 AWD transfer case used in the Bravadas that don't have a LO range or a mode selector switch. NP8 is the NP226 full-featured transfer case in the Envoy and Trailblazer (except SS)

 

[USA-1]

That was my guess. I found a 2009 np226 with 20k. Going to try and install it Saturday before the snow falls. Any tips?

 

[USA-1]

Replaced the transfer case today. We had a heat wave of 12 degree. Perfect weather to change a transfer case outside in the driveway. The old transfer case was leaking grey fluid from the case right above the clutch pack. It also had a noise coming from inside the case. That didn't seem wright. But it fixed 4wd just in time for the snow that coming.