2002 Blazer 4WD not working

Take it back, immediately.

It could be something minor, or it could be something severe, but anything that involves pulling the transaxle is going to be no fun at all.

--scott

I wouldn't call "feeling a little jerk" a conclusive test at all. If you put it in 4LO, the drive ratio should change NOTICEABLY- first gear won't get you past 10 mph or so. 4Hi is harder to tell, you need to actually get on a loose surface like sand or mud and make sure both front and rear wheels are digging in, or jack all 4 wheels off the ground and make sure they turn.

Get the wheels off the ground and see if both the transfer case and front axle are engaging or not. If the front drive shaft locks up, then the transfer case is engaging. If the transfer case is engaging but you can turn one front wheel without turning the other, then the front axle isn't engaging.

Rather that looking for a "jerk" did you checck whether the car went into 4LO? It should be immediately obvious whether the car was in low or high range simply by driving 30 feet.

The car shows no signs of change after selecting 4LO or 4HI. The only action is an audible click.

Then it is broken which can be bad new$....

Could be as simple as a bad switch or a dead t-case.

Mike

a good scan tool can relay the fault codes the trafer case has

Jste> Hello everyone,

Please let us know what this ends up at... Many, many, many of us have wrestled with these vac-operated 4WD systems which work fantastic when they work and are a major PITA when they don't. As others have suggested, it is likely something related to the vac system (switch, hose, actuator) or it's something a little more major such as the encoder motor or the actual TCCM itself. Many folks have noticed that when pulling the pass-side kick panel to expose the TCCM, the plug has been oxidized, shorted, etc. If you need the pin outs, etc, there is a fabulous website on this if you look for it. If you can't find it maybe someone will chime in as there was a guy very dedicated to this issue who had a blog setup with everyone's individual 4WD issues and a potential fix.

Good luck! If it makes anyone feel better, I am still having an issue with my

Take care, Andrew.

wrestled with these vac-operated 4WD systems which work fantastic when they work and are a major PITA when they don't.

(switch, hose, actuator) or it's something a little more major such as the encoder motor or the actual TCCM itself. Many folks have noticed

been oxidized, shorted, etc. If you need the pin outs, etc, there is a fabulous website on this if you look for it. If you can't find

who had a blog setup with everyone's individual 4WD issues and a potential fix.

tray, tested continuity on the switch and looked over the TCCM with a fine-toothed comb. When checking the diagnostics it comes back showing

chance to get the dealer to fix this issue, don't hesitate as they can be frustrating to deal with.

ve wrestled with these vac-operated 4WD systems which work fantastic when t hey work and are a major PITA when they don't.

tem (switch, hose, actuator) or it's something a little more major such as the encoder motor or the actual TCCM itself.  Many folks have noticed

has been oxidized, shorted, etc.  If you need the pin outs, etc, there i s a fabulous website on this if you look for it.  If you can't find

s issue who had a blog setup with everyone's individual 4WD issues and a po tential fix.

e with my 95 and will be replacing the vac switch and the axle switch in a last ditch effort to fix it.  I checked all vac hoses, ran new lines for good measure,

tery tray, tested continuity on the switch and looked over the TCCM with a fine-toothed comb.  When checking the diagnostics it comes back showing

e the chance to get the dealer to fix this issue, don't hesitate as they ca n be frustrating to deal with.

Thanks everyone for your posts. Unfortunately I am at a standstill with this project as the cold weather has been rapidly approaching. I do not have a garage at my house so I am stuck doing everything in my front yard. I was hoping to resolve this before the snow flies but we are getting snow up here in NH as I write this. Being that this is my sole transportation to work, I will have to hold off until spring. Thanks again for everyone's help.

-Jesse

The transfer case is electronically controlled. The front axle interlock is vacuum controlled.

according to what i read on mitchell ondemand it is electronic

"Steve W." wrote:

Not the first time for an oops. The front axle on the 02 uses the same vacuum controlled interlock as the rest of the line. Unless it has the optional AWD. That according to the factory manual, and the 02 Blazer sitting in the yard and the 02 S pickup in my BILs yard. Then add in few dozen I have worked on...

Apparently, not correct. My MOD shows a Blazer in 02, the front axle disconnect is vacuum operated with an electrical solenoid, so you're both correct.

Nope, The S/T Blazers were built until 05.

The Trailblazer was built from late 02 - current From 1999-02 it was actually an upgraded trim level on the S/T Blazers.

The only real change in the front axle disconnect from 83-05 was a switch in late 2000 to a solenoid that triggers the front vacuum instead of the transfer case mounted switch.