Brace yourselves for another noob question that has probably been answered before, but I couldn't find exactly what I was looking for. I'm a novice at best so the slightest variation in someone else's story from mine throws me off.

Ok, so I have a 2001 Blazer LT with push-button 4wd. 4-5 years ago the dash switch went out. I replaced it and all was good for a few months. Then, after not using the 4wd all winter, I tried to put it in 4hi and the button wouldn't even light up. The 4lo button would blink for a few seconds but wouldn't engage and then the 2hi button lit back up. The automatic 4wd button wouldn't light up at all. I didn't hear anything trying to engage either. I figured that it was the dash switch again, so I replaced it, but the problem persisted.

Sooooooo.... I didn't mess with it for a few years and then I decided to let a family friend take a look at it. The term "Shade Tree Mechanic" is giving this guy too much credit, but a free opinion is a free opinion. He told me that my TCCM needed to be replaced. I have no idea what he did or didn't check or how he went about his diagnosis. He wanted something like $500 bucks to replace it. I found the parts on ebay for like $50 but he said that the part has to be programed by a dealer. I found some TCCMs online that were around $200 but supposedly didn't need to be programmed and they claimed that they had "fixed" the notorious S10 TCCM issues. They weren't rebuilds, but newly fabricated parts that were built differently from the OE parts. I can't seem to find them online now that I feel comfortable enough to start routing around inside the truck though.

I've been watching videos and reading hundreds of posts and concluded that I need to check...

-The actuator, under the battery tray (for tears and proper movement)
-The vacuum lines (for tears)
-The transfer case control module wire connectors (for corrosion)
-The Transfer case control motor
-The transfer case vacuum switch

How do I test the transfer case control motor and/or the transfer case vacuum switch (if possible)? I can't seem to find anything on how to do it besides buying new ones and switching them out?

Also, I know for a fact that that my front, passenger side hub assembly needs to be replaced. That is on my list as well, but should I fix this BEFORE I work on the 4wd? I didn't know if this might cause additional issues with my 4wd not working.

I would appreciate any advice on other things to check but please be very specific, I'm trying to become more self sufficient with my truck but I'm at about a 2nd grade level, haha.

BTW, all of the dash switch light light up when I start the ignition.



THANKS!

 

The TCCM does NOT require, (or accept) reprogramming, it is plug & play.
Your NV236 transfer case does not have a vacuum switch on the transfer case. There is an electric vacuum switch located on the firewall, just about dead center. It has an electrical connector with two wires, and two vacuum lines. One line must have vacuum whenever the engine is running. The other line goes to the vacuum actuator under the battery tray and must have vacuum when 4WD is selected.

When you select 4WD, and it fails to shift, the system will default back to 2WD. On your 2001, there should be DTC's, (Diagnostic Trouble Codes) that start with "U" in memory that will indicate which circuit malfunctioned. You will need a scan tool capable of retrieving body codes, (the scan tools that the auto parts stores use are not capable of retrieving them). Post them here and we can help diagnose the problem.

 

Thank you so much! I will try and find someone with a scan tool or maybe even buy one for this and future use (any suggestions on what to buy?) and post the codes.

 

The Actron CP9580 is an entry level scan tool for around $250. Ebay usually has used higher end scan tools starting around $2K. If you're looking for new, you can easily spend $10K or more. The more you spend, the more things you can access. The more things you can access, the easier the diagnosis is

 

THIS is the "new and improved" TCCM that I couldn't find before.

1999-2005 GM transfer case control TCCM module shift S-10 Sonoma Blazer Jimmy

Worth the money? Or should I just order a used one for $50 off of ebay?

 

IF, through diagnosis, it is determined that the TCCM is the problem with your vehicle, this part should be considered as an option for replacement. If it's not the problem, you've wasted a serious chunk of change.

 

Right, I get that part, but what I'm saying is that the "new" part is close to $300 and a used part is $50. Is it worth the price difference to get the "new" one based on the specs that they give for the new part IF the TCCM does need to be replaced?

 

Personally, I'd get a used one. It takes all of 10 minutes to replace it, and you can replace it 6 times for $300! If money is not important, spend the $300 and take a chance

 

There is one major advantage to buying a used TCCM. Most of the ones I have seen on e-bay come with the wiring harness attached, ready to be spliced in. A lot of the time corrosion in that harness is the main problem.
That ad you linked is fishy, some uncomfortable half-truths.

 

Thanks for the input! Glad a asked for a second opinion. Yea I checked my wiring and connectors and they all looked pristine. I even "pulled" each individual wire out and they all looked factory new.

I checked the actuator and it looks/feels fine too. I'm trying to locate an inexpensive vacuum line tester.