Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 3 of 3 Posts

·
Registered
2003 chevy trailblazer_lt_ext
Joined
·
2 Posts
Discussion Starter #1 (Edited)
First, thanks for reading my first post here and for any help you might be able to give.

I went through the "Please read me first before making a post" in the 4x4 section. I've got a '03 TB EXT with the I6 engine and 230,000 miles. My service 4wd comes on when I'm in AWD and I turn, notice a binding (as if I'm driving on dry pavement in 4wd) and then it goes automatically back to rear wheel drive only.....with the light remaining in AWD and not going back to 2hi unless I turn off the vehicle. When I test the Transfer Case Encoder Motor and the Front Axle Disconnect Actuator, by switching back and forth between 2hi and 4hi, I do hear both motors function. Also, the vehicle does seem to engage into AWD until I turn, then the binding happens and it cuts out. I also tested if the diff is locking in 4hi as the post requests by jacking up the left front, putting it in 4hi and trying to rotate the left front wheel. This is locked as it should be. (post edit: I have tested it in 4hi and 4lo, where it seems to be working fine and doesn't cut out even in a binding/dry pavement situation.)

I should add one other problem that could be related. There is a vibration/heaving/grinding feeling (hard to explain) when I'm sitting at a stop sign (in 2hi...or really any). It originally was just until the vehicle warmed up but now is almost always. The brakes hold the car but it feels like the transmission is bogging down the engine, or pushing and slipping even though the vehicle is sitting still. It usually goes away if I slip it into neutral at the stop sign. Also doesn't really do it in park or reverse much. When I let off the brake and accelerate, it sets off fine and there's no slipping or anything, leading me to think its not really a transmission issue. I really have a hard time explaining the feeling. Sorry. I thought maybe it was an engine mount because it seems to be worse when the vehicle is leaning or on a hill (pushing the engine weight in one direction) and I can also feel a bit of it all the time when I'm going down the road....getting worse when I go over bumps. I went in with a camera and don't see any visible issues with the engine mounts....not that that is a guarantee that the mounts aren't broken I guess. This issue started at the end of the Winter last year with me just noticing the AWD issue this week because of the snow we got in PA. They could've started the same time though because I really haven't engaged the AWD since last winter.

I changed the front diff oil and the transfer case fluid. Both were pretty much up to the fill hole....down just a bit.... and didn't seem to be abnormally dark for 100,000+ miles. I know the previous owner changed both every 75,000 miles. I've kept up with Transmission fluid/filter changes every 75,000 miles or so also.
 

·
Registered
2003 chevy trailblazer_lt_ext
Joined
·
2 Posts
Discussion Starter #2
Update: the grinding sound at stopsigns WAS the engine mounts. I replaced them this week and its like new. I took suggestions that I saw on here to only use AC Delco parts for this repair. I'd suggest the same. They're great.

I could really use some suggestions for the AWD issue though. Anyone?:cry:
 

·
Registered
2004 gmc envoy_slt
Joined
·
2,466 Posts
First, the Trailblazer and Envoy do not have AWD, they have A4WD which is Automatic 4 Wheel Drive. In A4WD, the front disconnect is not engaged until a slippage is detected. Once engaged, the transfer case applies a controlled amount of drive to the front axle.

BTW it is not recommended to use the A4WD mode since it causes a harsh engagement and puts extra stress on the TC.

In your case, even though you hear both motor sounds, the TC Encoder motor could still be faulty or the disconnect is engaged.
 
1 - 3 of 3 Posts
Top