4WD Not engaging
 

Hey everyone, 2004 chevy blazer, with the 3 button 4WD panel...

Both the4WD HIand 4WD LOlight up whenI press them, they seem to work normal.Seems as if both buttons activate the transfer case (Ihear noise and feel it)but the front axle IS NOT engaging.

ran the diagnostic test by jumpering pin 13 to pin 5 (gnd) on the data link cablethen only got error code 1, reset that (on/off5x)and dismissed it as confirmation of a loss of power to theTCCM since 5 minutes before I had pulled the wiring harness off of it to look for opens then put it back on.

SO I ASSUME the problem is somewhere between/around the vaccum and the switch that engages the front axle.

So heres where it gets silly! i decided to look around under the hood, maybe take a peek under the battery tray at that vaccum thingy. I find a 1/8" (aprox.)ID hose sucking in air, way over on the drivers side, near the firewall, just floating around, sucking in air like a champ. this has to be it, yes? where does that hose connect to? does anyone have a diagram of the vaccum system? looks like it comes through a check valve and there is also a branched tee there in close proximity. i doubt that this is normal.

any help is greatly appreciated, thanks for looking at my thread. have a nice day!

RE: 4WD Not engaging
 

Here ya go:
http://i11.photobucket.com/albums/a1...33_vacdiag.gif

There should not be any thing between the vacuum switch on the t-case and the actuator (check valve or otherwise). But as the diagram shows, there is a check valve between the vacuum source and the T into the rest of the system (HVAC and transfer case).

RE: 4WD Not engaging
 

there may be the equivalent of a vacuum ball in the left fender right near where the hose is. Look like behind the ABS module-or for now put a screw in the end of it and try 4wd. Betcha it'll work but ultimately it needs to be re-hooked back up to it-vacuum 'canister' in left fender. Jerry[&o]

RE: 4WD Not engaging
 

Yes , upon further investigation i have realized this hose goes to vacuum reservior, or"vaccum ball" as you put it. i am going to attempt to reconnect this sonofabitch and try it out, thanks for that diagram swart, i was looking for one of those!

RE: 4WD Not engaging
 

NAILED IT, i guess there was insufficient vaccume without the resivoir to flip the transfer case vaccum switch, now everything works like a charm, thanks again guys!

RE: 4WD Not engaging
 

welcome.....come again! Jerry[&o]