So anyway, I grounded pin 13 to pin 4 and the 3 4wd indicator lights would flash twice then 3 second pause, and flash twice again.

little more back ground-In anything other than neutral the 4hi button is lifeless, but if im in neutral 4hi will react and flash then go back to 2hi. TCCM still clicks.

So what can i try before replacing the entire unit? I read you can jump the selector buttons to rule out the switch...I popped it out and all looked fine, no burns on the button contacts.

Is it still worth checking out the TCCM for loose/corroded wires?

I did read about checking the voltage on the encoder motor, but i dont have a dmm yet, and its snowy and cold. so that will have to wait.

edit for updated goodness:Just pulled the CTSY fuse and the 4wd drive fuse. both good. pulled the TCCM and checked connections, seemed ok, plugged back in.
started truck and 4hi light now locks in just like before, proper clicking etc. not positive it locked it in because i didnt drive, assuming it did.

1. I tugged on the wires on the back of the tccm harness and some are solid, yet some are able to move back and forth maybe 2-3mm is this normal?

2. is it necessary to clear the codes by cycling the ignition?

3. will this just be temporary because i just reset it?

I cant really see the transfer case since i have skid plates

 

By pulling the fuses, you have cleared the codes and effectively reset the encoder fault counter in the TCCM. This is what has allowed you to shift into 4HI. If everything else is working in the system, then you should have a functioning 4wd system for the time being.

This doesn't mean that it will work all of the time now. There was a problem that the TCCM detected with the encoder motor position. If you really wanted to get down to the nitty-gritty of it, 4 test lights could be used to back probe the A, B, C, & P inputs to the TCCM so you could monitor the states as the TCCM shifted the encoder. The TCCM is looking for certain values from the encoder in certain sequences while it is turning the encoder motor.

Here is a view of the encoder on your transfer case opened up and the table of values the TCCM expects to receive from the encoder as it moves the encoder motor:


So basically, when a channel doesn't respond with the expected value, the TCCM increments the fault counter by 1. Once the counter gets to a value of 32, the TCCM locks out 4HI.

For some possible causes; corrosion on the wiring at the TCCM is the #1 cause for encoder faults. It alters the connection resistance and messes with the readings the TCCM uses to indicate the encoder channel output. If there were a problem with any one wire (the A, B, C, or P sense wires or the common ground wire to the encoder) that causes an intermittent connection (broken wire inside the insulation, corrosion, loose connection, etc), the problem can be a royal pain to find.

For now, I guess I would just see if it happens again. Just know that sooner or later, your 4wd may not operate. Most can get by for a little while with the TCCM power cycle reset method, but that doesn't cure the problem and at some point, it may not work at all.

The encoder can be tested on a bench using an ohm-meter (multimeter set to the resistance scale). You are looking for the state changes and continuity between the ground (common) and and each of the channel outputs (A, B, C, & P). They should show a relatively low resistance (a few ohms). If any one of them shows a high resistance value (something higher than a few ohms, but lower than open) throughout the travel of the encoder, it may not feed the proper information to the TCCM. If the encoder checks out, then the wiring may be the problem.

This is all why just buying parts and installing them may not cure the problem.