Hi, I'm new here and trying to find some answers. I own a 2000 Blazer with the 4 button control for the transfer case. This morning my 4wd stop working during a snowstorm on my way to work. I had this truck for almost 2 years and only used the 4wd about 5 times during heavy snow. The dashboard switch has no lights coming on, it was on 4wd auto when that happened (normally keep it on 2hi) I was trying to get to work and since they didn't plowed the streets yet I set it on 4wd auto then it was some deep snow and the wheels loss traction the lights went off on the switch the service 4wd came on and went into 2 hi, now it won't do anything. I tried some things I read on other posts like disconnecting the tccm and the battery and I only turned off the service 4wd light but still won't do anything. Any help would be greatly appreciated since I can't afford to pay much for repairs. Thanks

 

Thats funny, im chasing the opposite problem, i can't get mine OUT of 4wd. It could be your switch, the Transfer Case Control Module, or the harness to it. Along with those in the path of failure, it can be a few vacuuming lines, the actuator underneath the batter, or the actually switch/actuator on the transfer case. Id start with the switch, then move to the TCCM, then look at the harness, c if there are any wires corroded. (the module is beind the corner kick plate on the passengerside.)

 

Thxs, I checked the connectors on the TCCM and it looks clean. Guess I'll go with the cheapest wich should be the switch. I got the service 4wd light off when I disconnected the battery and it didn't come back on after driving a few miles but still unresponsive, guess those parts can just fail without warning. I don't think it is a vacuum because it was working fine it actually was on 4wd when it turned off the light on the switch and went into 2wd so my best guess is that it is something electric.

 

TEST FIRST! There is TONS of information on this forum on how to properly diagnose your 4wd system. You can test the resistance of the switch to make sure that it is proper before throwing money into a new switch.

Is your 'service 4wd' light on? Even if it's not, you may want to get the TCCM codes read to see what might be stored. The codes may lead you to the problem so you only have to replace the faulty component rather than hope of getting lucky with the 'shotgun' approach.

 

The service 4wd light came on when it happened but later when I disconnected the battery it went off and is still off even after driving for about half an hour. I will look into how to check the switch because I can't afford to waste money. Thxs

 

I cannot reiterate this enough, if a light is on, that means that something has been found to be wrong with your truck. Before pulling the battery in hopes that it just goes away, get the codes read.

The crappy part about the NV236 4-button setup is that the codes cannot be read by the generic scans that most autoparts do for free. It needs a full function scan tool capable of accessing the TCCM to read the stored codes. I do not believe that the TCCM stores codes in its memory for retrieval even after a power reset so you may have to wait for the light to come back on.

 

OK, thxs, I'll wait to see if it comes back on. If I find the problem I'll post so it can help the next guy with the same issue.

 

That's a great attitude to have! Many just say THANKS, ITS FIXED or I got it working & <poof> they're gone. A huge part of this forum is being able to search for issues & seeing what others have done in order to fix them.
Personally I have a NV236 4 button trans with auto 4wd, so I'll be keeping an eye on this for any future issue I may have.

 

Hi all. First, Happy New Year!!!! My problem is solved. Just had to wait for a mechanic at my job to have some free time to take a look at it and he found it in 2 minutes (That's what happens when you don't know what you are doing,you have to wait for someone that does, lol. ) I did look at the fuse box but didn't find anything that pointed me at being for the 4wd, he pointed out to me that it says ATC or Automatic Traction Control. So all this time I had no 4wd because of a fuse, now is working properly. Thxs all for ur advice and I will stick around to learn some more just in case I need the knowledge later on.

 

Happy New Year & congrats!
Yes it's a good idea to stick around to learn more, trust me on that! lol
I said in another post to an electrical issue (I'm no guru) but even though a fuse "looks" OK, it still may be blown. It's always good practice to use a multimeter to test them. I know this wasn't the case as it wasn't anything that lead you to believe it had anything to do with 4x4, but that's why we're here, isn't it?