Having just gone through this exercise with a 4 button unit I can sympathies with you. I am always surprised at he cost of your parts. Be glad you are not in Canada. Apparently GM is trying to make up for all of thier losses here. The TCCM from the dealer $950.00 and dash switch was around $300.00. I was scaried to ask about the encoder motor.

 

Finished putting in the new transfer case encoder last night. Ordered the part from Rockauto.com for about $150. Works great so far!
Thanks again for all the help.
-Steve

 

Hi- My '01 blazer is stuck in 4wlo (4 switch selector). Is there any alternative to an enhanced code reader for diagnosing this problem? Thanks...

 

To read the codes? No.

To run through general checks, you don't need anything special for that. Read up on the NV236 and what others have done.

 

I checked the dash switch and resistance values are correct. Connections at TCCM are very good and I can hear the relays when battery is reconnected. Vacuum actuator and cable working freely. I checked all connections at the transfer case, etc. Seems, based on the threads I've read that I'm looking at an encoder motor. When I have cleared the computer and restart I can push 2H and it blinks but reverts to 4L and thereafter no response from pushing shift buttons. Does this point more toward the encoder than the TCCM? Thanks.

 

I have a 4 Button (Auto 4WD) select and am stuck in 4WD LO. I can sometimes fiddle back and forth, Neutral, Park, Drive to get it into 2W, all the while the 4WD LO LED is blinking...but as soon as I shut off I'm back on 4WD LO...

I tried pulling the fuse and am waiting to see if I can get a OBDII code to help diagnose the issue. btw: I've also experienced higher RPM's to shift as of late....before this problem now has me sidelined.

I have a Actron AutoScanner Plus Model CP9180 that I've tried to scan for codes from the TCCM, without success...I have an email in to their support staff to see if this scanner is capable...

suggestions?????

thanks in advance.

found out my scanner can't read TCCM codes, now I'm stuck. Everything points to a bad encoder yes? How do I prove it?

again, thanks in advance!

 

Getting the codes is the easiest way. There are a number of things that can go wrong. About the only one that can be tested without removing the encoder is the resistance on the encoder motor. You have to determine which pins in the main connector are for the motor itself and measure the resistance. Attempt a shift and then measure the resistance again. You should have something in the 100-400ohm range both times. If the second resistance is infinite or really high, the motor is bad.