Offroad Trailblazers and Envoys

4WD acting crazy

Something not working right?

by CNCwell » Fri Jul 08, 2016 7:06 pm

So my TB will not switch into 4WD. I have no warning lights and the light on the selector changes to 4hi/lo like everything is ok. When I turn the truck off and pull the 48 fuse then start the truck the 4WD will engage just fine. Once I switch to 2WD it will not allow me to switch back into 4WD unless I pull the 48 fuse again. I pulled the front actuator and it is engaging each time I move the selector switch. Any thoughts on what I should do next?
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CNCwell
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Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD

by TBYODA » Fri Jul 08, 2016 8:41 pm

A common failure is the disconnect. Did you happen to follow the tech doc linked below? Also what year and miles, have you change the transfer case fluid every 50k. Also another common issue is the 4wd switch, the contact oxidize. Try moving it with the TB off from 2wd to 4lo about 30+ times that helps clean them. Switch is cheap. 20-$30
http://www.offroadtb.com/articles/tech- ... wd-system/
2008 TB Radflo coil overs, Z71 rear springs, 2" spacer, skyjacker N8030 shocks, LT285/75R16E Goodyear MTR

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by CNCwell » Tue Jul 12, 2016 10:25 am

Yeah, I chased it down to the disconnect. However, with that being a mechanical piece the fuse thing it throwing me, because it will work once after I pull the 48 fuse, then it will not work again until I pull the fuse again. I think i will replace the disconnect and see what happens.
Life shrinks or expands in proportion to one's courage.
--Anais Nin

All my money
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DriveTrain: 4WD

by KingBird » Tue Jul 12, 2016 1:24 pm

In the past, I've heard that when people have the same problems you're having its the TCCM going on the fritz but it could just be a faulty electrical component in the disconnect solenoid that needs a reset to work once. I keep spares of just about everything in the 4wd system and I even went so far as to install a switch to the main power for the 4wd system so that I could reset it from the cab for troubleshooting purposes. I hardly use it anymore though. An AWD "disconnect" would solve this problem for good...
Bravada G80 3.73 converted to selectable 4wd.
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