Hey guys, I got a 2004 Blazer with 4 wheel drive, I've been trying to fix the 4x4 but nothing has worked.

Heres whats happening, the 4x4 only seems to work rarely, it used to work flawlessly till this winter, it has the 3 button selector on the dash when it's not working non of the lights on the buttons light up and nothing will happen when I hit them, sometimes the buttons will be lit up but I try to change to 4 wheel and it makes a click and the light on the button goes away and they are all off again.

Ive replaced the switch on the dash and it worked for a couple days after but then stopped working again, i changed/checked the fuses and nothing changed, I checked the connection to the tccm it looked a little corroded so I used some cleaner on the pins and nothing changed again and I also checked the vacuum actuator under the battery tray and it moves just fine and is not frozen.

Does anyone have any clue what's wrong? Or stuff to try? Thanks.

 

Does the TCCM repeated click or did it? That is a symptom of the TCCM going bad.

 

I don't think I heard it clicking before, I would try it but the switch currently does nothing

 

When the TCCMs start going bad, they will click repeatedly trying to get the 4wd system to engage. If it is doing nothing, that is not necessarily good evidence if the TCCM is bad or not.

Have you tried checking the OBD codes? Is your 4wd warning light on?

What was the "click" you reported in your first post? Was it the transfer case engagement?

Have you checked if your vacuum lines are good and there is vacuum at the front axle actuator when 4wd is called to engage?

In order to do a proper diagnosis, you might have to lift up the whole truck and test if the transfer case is engaging or not and then if the front axle is being engaged too.

 

I think the clicking could've been the tccm, I have not checked all the vacuum lines, there is no service 4x4 light on and using the cheap scanner I got it says I only have engine ones, maybe soon i can try my brothers autel. Thanks