I have a 2002 3 button system, I would like to know if anyone has a cross to what each encoder channel refers to in position. A, B, C, and P goes to what postion 2hi, 4hi, or 4lo. And does the encoder have to open or closed for the tccm to know what position its in. I cant find it anywhere.
Thanks
Buddy

 

I have done some experimenting on the the enoder by opening it up with a demerl tool. I was getting an ecoder fault code in my TCCM (code 2) often, I did all other diagnostics and they all led me to the encoder. I ohmed out my encoder while in 2hi. It read A, B, and P, are all closed to ground. I thought this was weird, so I figured the encoder was all buged up inside. Well I bought a new encoder motor assy and replaced the one in the blazer. Now back to the experiment, I cut open the encoder to hopefully find bad fingers or something wrong, well every thing seemed to be fine. I figured out what channel goes to what shift position, A goes to 2hi, B goes to 4hi, C goes to 4lo, and P goes to transistions between shifts. After figuring that out, I knew my encoder wasn't reading correctly when in 2hi, it read the A and B where closed giving the fault after it racked up when the TCCM does a check every time it started up. It was out of calibration, The encoder assy is screwed to the shift assy and has slots to rotate it a couple of degrees. If I rotate it slighty in the correct direction the 2hi reads A closed as it should. I wish I found this out before buying a new encoder motor assy.
I hope this helps for anyone having this problem that doesn't have a corrsion or TCCM problem.

 

I have the same problem. Shows (flashes) code 2, sometimes the tccm clicks & shifts into 4hi, mostly it flashes 4hi & 4lo then defaults back to 2hi or gets "jammed" (persay) & won't do crap till I put it in N (trans) then put it into 4lo or 2hi and it is fine. Of course during the warmer months it all works fine!
I'll have to see if what You had mentioned "clocking" the motor on the decoder is an option for Me in this case. I hope this does the trick seeing how winter is comming & My money is too tight for "anything" right now, lol! If You (or antbody else) has more on this subject, please help. I'm sure I'm not the only one whom can't afford a $200 problem right now, Thanks!
Yes, it's a Jimmy and this forum is the most helpfull around, Blazer/Jimmy whats the differance? oh I know-shifter location, rear bumper, head lights, badges, wheels (mine are chevy wheels tho. GMC's don't look as good!)

 

I just checked what position my new encoder is at when in 2hi. A, B, and P are going to ground again like the old one did.
Before I adjust it does any one know which ones should be grounded at 2hi, 4hi, and 4lo just to check my work.

 

Hi, to whom ever can help.
Refering to the posts above, I am also looking to know if anyone knows what the shift pattern is in in degrees. How far does it go from 2hi to 4hi and then to 4lo.
But I would realy like to see what channels are gounded in the different positions also, 2hi 4hi and 4lo.
I need this info in order to help me understand if I need to calibrate the encoder.
Thanks

 

I just mapped my encoder, here are the results.(it is a copy and paste from notepad)

ENCODER MAPPING (WORK IN PROCESS)
(CLOCK WISE DIRECTION, LOOKING INTO FEMALE ADAPTER SIDE ON ENCODER ASSY, ONLY LOOKING AT EACH TRANSITION OF CHANNELS,
THERE ARE 6 "P" POSTIONS AND THEY ARE VERY SHORT)

START(FROM MECHANICAL STOP)
............A & C
............A
1ST-P & A
............A
............A & B...........2HI??
2ND-P & A & B--------2HI (READING WHEN ON T-CASE)
............A & B...........2HI?
..................B
3RD-----P & B.............4HI??(possible?)
..................B---------4HI (READING WHEN ON T-CASE)
..................B & C.......4HI?(possible?)
4TH-----P & B & C
..................B & C
.......................C
5TH---------P & C.......4LO??
.......................C-----4LO (READING WHEN ON T-CASE)
..................A & C.......4LO?
6TH-----P & A & C
..................A & C
END(TO MECHANICAL STOP)

A & B OR A(HIGHLY UNLIKELY) CAN BE 2HI
B OR B & C CAN BE 4HI
C OR A & C CAN BE 4LO

I would like to check this with another vehicle, I may use my inlaw's 97 Jimmy when avalible

I am thinking calbrating is not needed, any thoughts on my findings?

 

As with a lot of 4wd problems, the information is only a search away...

No calibration should be required for proper operation of the encoder motor.

For a full break down of the channel outputs, check the NV233 troubleshooting article link I posted in the NV233 transfer case / encoding motor switch Tech Article (DIY) thread by error_401. 2HI is channel C, 4HI is channels A&C, Neutral is channel A, and 4LO is channels A&B. So your locations for 2HI & 4LO are reversed.

For an illustration of the gates and channel locations inside the encoder, check the NV243 troubleshooting article link posted in the same Tech Article I linked to above.

 

Thank you very much, I have read the thread that you linked before but the links for the transfer cases came back as errors when I clicked on them.
Now they are not coming back as errors and I am going to read them.
As I did some more trouble shooting I agree that the encoders dont need to be calibrated either as you say.
I just need to know how things tick.
Thanks again