Hey guys!

So recently the 4x4 on my Blazer 2001 LT does not engage. I click on the 4 hi button and the light dissapears and does not blink, it does not change over to 4 hi. If you press the 2 wd button the light comes back on and it stays just fine.

So today I checked the 4x4 actuator underneath the battery and it does not move or click or do anything while the 4 wd buttons are being pushed inside the truck. A coworker believes it could be a grounding issue but I have no idea what to do.

Anyway, as we were putting the battery back on we couldn't get the metal platform that holds the battery back in place so my dad yanked some wires out of the way. I am pretty sure they are part of the 4x4 vacuum system but when he yanked on the small rubber tube by the negative battery terminal the plastic connector broke off on the inside of the tube and now its just taped on. If someone could tell me what the vacuum tubes are for that would be awesome. (Picture is attached)

TL;DR

-4x4 does not engage on Blazer 2001 LT
-Need help finding out what part this is (picture attached)

Thanks a ton!!

 

First question: how many buttons on your 4WD switch? The three-button switch has a different troubleshooting procedure than the four-button switch. Once we know which system you have we can proceed with troubleshooting.

 

It would be 4 buttons counting the Auto 4wd

 

Unable to tell from the picture exactly what broke; is it the vacuum line going into the actuator? If so, time for Dad to get a new one...as a seal is required for 4x4 to work.

Couple of things to check: 1) the connector at the TCCM. Located under the passenger side foot trim panel. Just pull the panel off...easily. Check the contacts for corrosion and clean.
2) Remove the 4x4 button assembly from the dash. Take to a work bench and CAREFULLY separate the two halves of the assembly to expose the circuit board. Re-flow every solder connection using a 25W soldering iron. DO NOT USE a soldering gun...too much heat and will damage the circuit board. If you have never soldered before you can either learn or find someone to show you....even YouTube. Re-assemble switch and re-install.

Now see if the 4x4 works.

 

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The tube that broke is right next to the negative battery terminal in the blazer. There is two small tubes including the broken one and one blue electrical plug.

thanks a ton for the info. I'll be working on it tonight

 

This is exactly what the mystery part looks like except its by the engine coolant tank and negative battery terminal