no 4x4 -2004 chev

[Jon Scully]

hey there- i have push button 4x4, that is not working- looks like both drive shafts ar3 turning-whats next?
its a friends truck---i am used to old school locking hubs

[Zoomad75]

Chances are the front axle actuator isn't doing it's job.

[gchemist]

Send me a PM with your e-mail address. I'll send you some PDF files from a factory manual. It will help troubleshoot the problem. The engagement system is on the axel. It's the primary reason most 4X4 systems fail to engage.

[68C15]

to accurately diagnose these a guy needs to know how the system operates

the shift module tells the shift motor to engage X case based on inputs from dash switch, vacuum switch on top sends vacuum to diaphram under battery, that pulls cable to engage a dog clutch on front diff

half of the time I find a bad shift motor, half the time I find a bad actuator diaphram.

most of the problems with the motor is the encoder (position feedback sensor) while sometimes it is the motor being stuck due to lack of useage.

if the vacuum actuator has a broken diaphram you should replace the vacuum switch on top of the X case due to ATF being sucked into lines. follow it up with a good hose flushing with brake cleaner and blow gun.

[Jon Scully]

Thanks for the feedback-- So here is the deal!

IT turned out to be a broken diaphram in 4x4 actuator under the battery --- It works great now.

The problem/question I stiull have is why there was oil in the old diaphram? It seems like there was oil in the vaccum line at one point....but was dry......

SO my question is ---Where is the oil coming from?

Thanks
jon

[Jon Scully]

OK sorry-- just read the last post more carefully....DOes the ATF in the lines mean I should change the 'vaccum switch on xcase' --- Do you have the part number pic perchance?

Hope I did not ruin the 'new' part by not changing the switch


jon

[68C15]

motormite 49315 IIRC
http://www.autozone.com/autozone/par...ntifier=347145