i have a 2003 tb with the electronic switch stuck on A4wd. when i start truck all lights light up and with switch at 2 hi, which i hope it shifts back to, the light settles on A4wd. a code of 0321 appeared when scanned. what may be the most common problem of this? want to say i don't have money for the dealership to investigate. i am hoping that it has something to do with the transfer case motor which looks like an easy job to do, but i don't want to chase the parts. any feedback on this? thanks
2003 trailblazer stuck in A4wd (Code C0321)
- Thread starter joller
- Start date
Hi! I broke your post out into its own thread so we can have a specific discussion about it.
Your code was a C0321 (the "C" is significant when other people come searching in the future), and it has to do with an encoder motor BRAKE function.
The encoder motor on the 4WD vehicles that use the NP226 transfer case (Trailblazer except for the SS, Envoy) have three functions, using 7 pins on their conenctor
1) The motor control itself
2) The position feedback sensor (the "encoder")
3) A solenoid brake that keeps the motor from moving inadvertently even if a TCCM fault tries to change modes to 4LO, which could cause very bad things to happen if it occurred at highway speeds.
So a fault on the brake function is what caused your code, and it could be either wiring from the TCCM down to the encoder motor, or a fault in the motor assembly itself. You should start by carefully inspecting the wiring down at the encoder motor, and replugging the connector a few times in case a contact is dirty. If you have a voltmeter, you could confirm all this by downloading the schematics we have on the site, or running a Google image search for "trailblazer tccm schematic". Of check Ebay for used encoder motors, which look like they have for a low price of $80 or best offer. Many sources for new ones, including a Dorman aftermarket replacement that can be less $$. Amazon, Ebay, Rockauto, local parts stores.
Your code was a C0321 (the "C" is significant when other people come searching in the future), and it has to do with an encoder motor BRAKE function.
The encoder motor on the 4WD vehicles that use the NP226 transfer case (Trailblazer except for the SS, Envoy) have three functions, using 7 pins on their conenctor
1) The motor control itself
2) The position feedback sensor (the "encoder")
3) A solenoid brake that keeps the motor from moving inadvertently even if a TCCM fault tries to change modes to 4LO, which could cause very bad things to happen if it occurred at highway speeds.
So a fault on the brake function is what caused your code, and it could be either wiring from the TCCM down to the encoder motor, or a fault in the motor assembly itself. You should start by carefully inspecting the wiring down at the encoder motor, and replugging the connector a few times in case a contact is dirty. If you have a voltmeter, you could confirm all this by downloading the schematics we have on the site, or running a Google image search for "trailblazer tccm schematic". Of check Ebay for used encoder motors, which look like they have for a low price of $80 or best offer. Many sources for new ones, including a Dorman aftermarket replacement that can be less $$. Amazon, Ebay, Rockauto, local parts stores.
roadie it is so funny that you replied back to my prob. i read your online stuff on trailvoy and you are the reason i came to gmt yesterday. i saw a note that everyone moved to this site. i am still getting used to using this site. anyway i did take apart the plug seemed clean. i didnt do the other plug that seemed to go into a sensor. i called junk yard for used motor which they have for the 80 bucks. i like that you pinpointed a problem and narrowed things down. i don.t have experience with the electrical part but i think i can do the mechanical part. first i would like to know how to find out if used motor works. next, if switch is in A4wd (i am only thinking it is due to the light stuck on it), does 2hi have to be engaged before the motor gets replaced? i saw this mentioned in diy video but it never really discussed the process. could you also direct me to the proper place of the schematics or possibly a tip on checking the power source for dummies. lol thanks jay why was the switch eliminated as a possible problem? also is the encoder motor dorman 600 903. hoping i am on right track
Not funny at all! You might even come to EXPECT it.joller said:
Thanks for the kind words, but I'm one of dozens of competent question-answering folks that moved here. As far as we can tell, the couple of folks who bother to answer questions on trailvoy anymore are clueless goofs with bad memories who give wrong answers except to a few issues where they parrot back one of OUR archived responses!
As much as the new owners we moved in protest to avoid try to suppress the truth, it still seems to get out. Doesn't it.
Difficult to test it on a bench without some electrical experience and the schematics. You can plug it in to your vehicle while not attached to the transfer case, and see if it moves and the mode control switch does the expected thing.
You should be able to choose whatever mode you want it to be in, but why not choose A4WD mode where you said your transfer case shaft was already in?
Schematics are in a Stickied post here on the forum, or as I posted, you can easily find the 4WD sections in a Google image search. Hope you're not just using a smartphone to access the forums.
Statistically, I've read hundreds of problem reports of 4WD failures, and switches are most often bad with slightly different behavior than yours.
Man, a couple of paragraph breaks might improve the flow of your next few posts.
Yes, that's the Dorman part number.ok roadie i will not ask all questions at once. no prob. i will try to ask this one last question as best i can. there is a gear coming out of transfer case. this gear is rotated to the A4wd mode, at least that is what i am thinking. when i get the new motor, does the inside splines on the motor have to be rotated to match those of the transfer case? or vice versa? trying to understand why it was mentioned that 2hi had to be in gear to put new motor on. they could be wrong though. thx for your time
The motor should match the splines, but you can manually rotate the transfer case shaft if you need to, or command the motor before you install it. I've never actually taken my encoder motor off, however. So this is just theoretical knowledge that others have really done.
