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my 2003 sonoma started acting out after i recently replaced the transfer case vacuum control switch due to transfer case fluid loss from a defective, leaking vacuum switch. i replaced switch and refilled transfer case and once truck was first driven at freeway speed the front axle began to grind and fuss until i slowed and pushed 4x4 control button and engaged front axle and switched back to 4x2. this worked until i was able to nurse truck home and slow to engage 4x4 and switch back to 4x2 until it started grinding again. it seems the new switch was defective and caused my trouble. i decided to disable vacuum actuated front axle control and switch to an aftermarket cable operated front axle locking kit. installation was fairly simple and it works okay but i was hoping to remove the vacuum hoses from transfer case vacuum switch to prevent a possible problem in the event the replacement switch developed a leak as the original switch did, and suck the fluid out of my transfer case as before and run my transfer case low or dry and have the fluid foul my heater controls as previously occurred . does anyone here know if i can remove the 3 hose connector on transfer case vacuum switch and plug it now? i wasnt certain if it was possible and left it connected. wasnt sure if it was used for another function or indicator or some such thing that i wasnt aware of. any help or suggestions from an owner with manual front axle lock? thanks for any advice
 

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Up by the ABS pump there is a tee going down there. If you cut the line and plug it there will be no worries of ATF getting into everything vacuum operated. Hope for your sake none got into the HVAC system. It's possible ATF got into the actuator under the battery and ruined the diaphragm.
What brand replacement switch did you use? The Dorman ones are junk. Don't fit on the lines correctly. Never heard anyone having an issue with ACDelco OEM replacement. The blue striped one is the new improved one.
You may want to check your TC fluid level. It usually indicates the TC is overfull if fluid is being sucked into the lines.
Over full is caused by a defective input seal on the shaft from the trans. I wouldn't drop the TC just to repair it. Wait until you have it out for some other reason. Just check the level when you do any maintenance.
 

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thanks for reply and your good advice. i dont remember the brand of the replacement vacuum switch, but it may have been a dorman part i purchased from local franchise auto part supply store. i remember it was not a delco part and was a blister packaged part. i found transfer case fluid a bit low and topped fluid up to full level. hvac controls are contaminated with ATF and the drama continues with heater and defroster operation. i have been unable to correct my defroster headaches yet but progress is slow. vacuum reservoir hose and check valve were oil soaked and soft and vacuum hose next to right side exhaust Y pipe was burned through by heat and i was hopeful my defrost defect was caused by these issues, but no luck yet. i am still making feeble attempts to troubleshoot heater mode operation but have not made any progress yet. i cut off an old wood clothespin and zip tied it to defrost door actuator to force defrost door open until a proper troubleshooting and repair can be performed. i will check back with progress or lack of progress here when i attempt proper repair. will post that headache on new thread as drama continues. any help or advice is most welcome. best regards
 
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