auto 4wd
 

the lights on the 4wd were flashing and the service 4wd light was on. after talking to a few people on here i looked around and found a broken line. so i put the new vac line on the actuator under the battery and the lights stopped flashing. new problem is that it feels like the 4wd is partially engaged at all times and the only button that stays lit is the auto 4wd. no other button works, but occasionally the 2wd lights up. i took the family off roading and she walked through the deep sugar sand and up the inclines like she was in 4hi but the 2wd was lit. any thoughts?

Sounds like the vacuum switch is stuck open. See what happens when you disconnect the vacuum line to the actuator under the battery. With auto 4WD, you probably have a vacuum switch on the firewall under the hood. If not there, then on top of the transfer case.

well the line from the firewall to the actuator under the battery was disconected for 2 weeks and i didnt get any response besides the flashing lights. i didnt know about the one on the transfer case so i have to look to find were that is. i was thinking about putting a blast of air through the system with compressed air to see if there was something blocking it. you think thats a bad idea? thanks

If you have a 4-button switch in the dash with auto4wd option, then you will only have the vacuum switch on the firewall and nothing more on the transfer case that affects the front axle engagement.

Is the 'Service 4wd' light on in the dash cluster? If so, the easiest method to determining what's wrong is getting the TCCM scanned for codes with a capable enhanced scan tool. If that isn't an option for you, you can try checking the connector at the TCCM for corrosion & testing the switch resistances per the NV236 tech article. Disconnecting the TCCM will erase any codes that are present though.

Seems like good place to ask. I have the Auto on my 01 blazer ls zr2 and I obviously have the solenoid on the firewall not the switch on t case. But I found the connection loose at the solenoid after replacing it, not letting vacuum sometimes through causing the lights to just keep blinking fixed the connection vacuum works actuator seems to work but how far should the cable pull out? I disconnected pulled it with my hand only moved little but heard it click. But when I push it back in doesn't click or make a noise and hardly moves but the actuator extends fully.. also when I put it in 4lo the actuator sucks all the way in not like just 4hi is this normal? I feel as if my 4wheel doesn't disengage but it says it does..help??

kody070, that's covered in the tech articles. Check out the one that talks about clicking in the title. :icon_wink: And please try not to ask off topic questions, as in questions that are very loosely related (if at all) to the topic at hand, in someone else's thread as it is not very nice to the OP.

swartlkk i took it to a trans shop and they said it was the switch. just replaced it now i can switch from auto to 2hi but nothing else. called them up and they say its the transfer case motor. sound right or no?

Two options. Start doing the diagnostics yourself. The stuffs pretty much all here or trust them. And yes it very well could be. They do crap out.

Sounds to me like they are trying to take your money!! A reputable shop would have fixed and tested it right the first time so you didn't have to come back just to get more parts replaced. They will pull you into this spiral of replacing things and just end up costing you a bunch of money. Like spitty said take what Kyle is giving you as well as do some searches on here and you will learn that the 4wd systems are actually really simple to diagnose and repair yourself in most cases. There is a wealth of info to be had here and you already one of IMO the most knowledgeable people helping you out and giving you advice. Plus its always a good feeling to say you did it yourself and then take yourself out for a beer or 6 with money you are saving yourself.