Is MT-2500 still here?

[denise2580]

I posted a while back about a 4wd problem with a 2000 blazer. You said to get the codes and post back. It took a while but my son took it to school at the ATC and put it on their scanner and got a U1026 and he said it kept loosing communication with the scanner. His teacher said it was an electrical problem with either the computer module or the dash switch. The original problem was that the service 4wd light comes on after about .5 miles of driving and then it progressively gets worse and the dash switch starts flashing and if I come to a stop at a red light or something it drops down to 4w lo by itself. The dash switch has gotten worse to the point where no matter what I push it will not respond. I used to have to put the transfer case into neutral to get it out of the 4 w lo but now it won't even do that. So I guess after all this rambling my question is do you think it is the dash switch or the computer module? Since the switch stopped responding it is my thougth that it is a bad dash switch that I should replace first. The computer module is so expensive I hate to change it if it is not the real problem. So if you have an opinion on this or anyone else reading this post on the forum I would appreciate it. It seems that these type of problems are so hard to figure out. I just can't seem to figure out this 4 wd problem and it is all too expensive to just start replacing stuff without knowing for sure. I don't know what else to do. Thanks to any and all help!

[Rmbodie]

Yes , he just posted about an hour before you did . Rob

[MT-2500]

Originally Posted by denise2580

I posted a while back about a 4wd problem with a 2000 blazer. You said to get the codes and post back. It took a while but my son took it to school at the ATC and put it on their scanner and got a U1026 and he said it kept loosing communication with the scanner. His teacher said it was an electrical problem with either the computer module or the dash switch. The original problem was that the service 4wd light comes on after about .5 miles of driving and then it progressively gets worse and the dash switch starts flashing and if I come to a stop at a red light or something it drops down to 4w lo by itself. The dash switch has gotten worse to the point where no matter what I push it will not respond. I used to have to put the transfer case into neutral to get it out of the 4 w lo but now it won't even do that. So I guess after all this rambling my question is do you think it is the dash switch or the computer module? Since the switch stopped responding it is my thougth that it is a bad dash switch that I should replace first. The computer module is so expensive I hate to change it if it is not the real problem. So if you have an opinion on this or anyone else reading this post on the forum I would appreciate it. It seems that these type of problems are so hard to figure out. I just can't seem to figure out this 4 wd problem and it is all too expensive to just start replacing stuff without knowing for sure. I don't know what else to do. Thanks to any and all help!

Yes I am still here. Can not stay away for some reason. Maybe a habbit.
The code i can not find listed for it. But a lot of U---- codes are communcation problems. Which is wiring or a bad computer/module.
I would check the wiring and wiring plugin on the Transfer case pcm/module and the rest of the computers to. Even another computer can knock out communcations. Also scan the other computers for proper operation and comuncation.. ABS/engine / sir/ body/transmission.
Unplug the computers and check plugins. Then plug back up and take off battery cables and touch the together and drain memory out of all computers.
I have saw some computers lock up like PC windows and a reboot will get them going again.
Also check for good power and grounds to the computers.
And the wiring and plugin on the transfer case.
Then drive and recheck for codes if/when it acts up again.
If the school has a scanner or shop they should have a repair flow chart for the switch test. If not I will try to post one back to you.
Let us know how it goes and I will keep looking for tha code no.
MT

[MT-2500]

Ok I found the code U1026
OBD11 code pertaining to no engine RPM problem.
http://www.troublecodes.net/OBD2/
Not sure if it would knock out the transfer case shifting but could.
It needs to be checked out.
Get it on a engine scanner and check the engine RPM readingsin scanner.
MT

[denise2580]

Thanks rob for letting me know MT was still posting!
Thanks MT for the information! I did get papers on checking and testing different things on the tccm and switch I had also purchased the service manuals from gm when the problem first came up. It seems that without a good scanner it is hard for me to follow the manual and sending it up to school with my son was nice for an idea but I only get 1/2 of an answer from him, I am not allowed to go up there with him to see for myself. I did send him with 2 pages of things to check and the way I wanted them checked but then he gets thinking on his own! His teacher said it was a definate electrical problem. Can or do the tccm's go bad on a car that even though it is a 2000 it only has 32,000 mi and it has only been out in the snow twice since I have owned it cause I don't want the road salt on it! So basically it sits in the garage untill I feel like taking it out, it is my "dress up" car so to speak! And I don't let anyone else drive it! Do the tccm's or switches go bad from just sitting or dampness? Sorry for all the ?'s it is very frustrating to me and I have no intention on taking it somewhere to get fixed and ending up paying for some jerk that knows less than I do for nothing! So once again thank you very much for all the information and listening!

[MT-2500]

Originally Posted by denise2580

Thanks rob for letting me know MT was still posting!
Thanks MT for the information! I did get papers on checking and testing different things on the tccm and switch I had also purchased the service manuals from gm when the problem first came up. It seems that without a good scanner it is hard for me to follow the manual and sending it up to school with my son was nice for an idea but I only get 1/2 of an answer from him, I am not allowed to go up there with him to see for myself. I did send him with 2 pages of things to check and the way I wanted them checked but then he gets thinking on his own! His teacher said it was a definate electrical problem. Can or do the tccm's go bad on a car that even though it is a 2000 it only has 32,000 mi and it has only been out in the snow twice since I have owned it cause I don't want the road salt on it! So basically it sits in the garage untill I feel like taking it out, it is my "dress up" car so to speak! And I don't let anyone else drive it! Do the tccm's or switches go bad from just sitting or dampness? Sorry for all the ?'s it is very frustrating to me and I have no intention on taking it somewhere to get fixed and ending up paying for some jerk that knows less than I do for nothing! So once again thank you very much for all the information and listening!

You are welcome.
Yes the TCCM do go bad sometimes. And the switch to.
The No communcations points to a bad module /computer but it may be any one of them . They are all tied together. If you find one not communcating with scanner that is usually the one. That is where the scanner comes in you need it to see what is going on.
Also with a scanner you can check out the switch operation.
Good Luck and let us know how it goes.
MT