Just got my Dorman TCC Motor/Encoder delivered. My Blazer is an 1994 S10 4.3L V6 4WD vin W / 233 transfer case.

Alldata and any information I have gone over has not told me how to properly index the Transfer Case Control Motor/Encoder for installation JUST be careful and do it!

The included instruction read:

Installation:
*Clean mounting service …

*Remove plastic alignment insert from new motor

*Look at the position of the transfer case shaft and see if it matches up with the receiving end of the motor. If it does not – it may be necessary to manually turn the shift shaft on the transfer case with a crescent wrench to align it with the motor, Check service manual to see what gear position the transfer case should be in to perform this procedure.

*Some motors may be able to be aligned to the transfer case shaft by inserting a half inch drive ratchet it the drive opening of the motor and turning until the position of the motor matches the transfer case shaft. This procedure is not recommended as some motors are not able to be turned using this method. Damage to certain motors will occur if this procedure id used.

*Do not attempt to put power to the transfer case motor to move the receiving end for alignment. Doing so may lead to internal motor damage.

* Once the motor is indexed properly to the transfer case – install the motor by holding it flat against the transfer case and thread in the mounting bolts.

Help

 

Since you have the NV233, you can use either reindex the drive using the 1/2" rachet or just turn the shift sector shaft on the transfer case to match the encoder motor.

Their form letter is used for all encoder motors including those used on the NV236 transfer case which has an integrated brake assembly to lock the position between detents on the transfer case. The NV236 encoder motors cannot be turned without first energizing the brake circuit inside the motor to disengage the brake. Failure to do so will result in damage (most likely stripped gears).

I would recommend seeing how they line up first and going from there if you need to reindex either the encoder motor or the transfer case.

 

I was registering a code 2 Encoder fault, so I am only assuming the indexing will not be correct. As with the picture, there is no match up quality of the TC Motor, which seems to infer it could be 180 degrees out of sink and still mate together.

The blazer is in 2WD as the front propeller shaft rotates freely and is not locked.

So in the event the Transfer Case matches the motor/encoder assembly, how do I know it isn’t 180 degrees out.

 

It cannot be installed 180 degrees out. It is physically impossible. The encoder rotation & the rotation of the shift sector shaft in the transfer case are limited to ~90 degrees.

 

So are we saying the transfer case shaft, that mates into the Motor/Encoder unit will only turn 90 degrees.

Thus the Motor/Encoder unit being preset in the correct position, and the transfer case shaft only turning 90 degrees, it would be impossible to achieve an incorrect alignment with the Motor/Encoder in the event the transfer case shaft needed to be adjusted to match the Motor/Encoder.

 

Thank you, for the helpful info.
Since I am unfamiliar with internal operation of the transfer case, to be able to turn the transfer case shaft for possible indexing, does the transmission have to be in neutral or park or does it matter.

 

If the transfer case is in 2HI, then the front shaft will turn freely. If it is stuck in 4HI, you will need to get all 4 wheels off the ground, safely supporting the vehicle on jack stands at all 4 corners. Then place the transmission into neutral. You should then, with some effort, be able to turn the front drive shaft.

As far as the shift sector shaft (what the encoder motor turns), that should be able to be walked through each of its positions with a wrench. The range shift (HI to LO or vice verse) may not line up perfectly as there are splines that need to mesh together properly to shift between HI & LO ranges. If that is the case, rotation of the rear drive shaft while attempting to manually shift the transfer case will allow for proper, easy engagement. Again, you'll need at least the rear wheels up in the air & safely supported to be able to rotate the rear drive shaft.

 

Ok great, I feel prepared. Tomorrow (Saturday) is going to be in low 50's degrees, I feel prepared and plan to get it on. Thanks

 

My installation of the Transfer Case Motor/Encoder. Equipped with an impact gun, 1 1/8 inch socket and T bar puller for the yoke.

The front wheels were up on a ramp and rear tires secured.

Disconnected the negative battery terminal.

Removed the bolt on the electrical connection and removed the connection.

Removed the two retaining caps on the front propeller shaft universal joint and
moved the front propeller shaft to the side.

The transfer case yoke rotated, so was not engaged. Held the yoke with a secured pipe wrench and removed the nut on the yoke with the 1 1/8th inch socket and impact gun

The yoke just slide off and the T bar puller wasn’t needed.

After some fluid drained, removed the 3 bolts on the Transfer Case
Motor/Encoder to the transfer case and removed the Motor/Encoder

The new Motor/Encoder had a plastic retaining cap on the shaft that mates to the transfer case shaft.

Removed the plastic cap over the Motor/Encoder shaft and found the transfer case shaft were NOT in alignment.

Considering the how the Motor/Encoder shaft was in relation to one of it’s bolt holes, took a 6 inch or so long 1/4 wide piece of wood and held it in the slot of the transfer case shaft to orientate myself how the shaft needed to be turned. I used a small 6 inch crescent wrench to turn the transfer case shaft, took a little more pressure than I was expecting, but you could feel the shift sector plate working against the spring loaded poppet plunger. When the shaft was rotated or indexed to mate with the orientation of the Motor/Encoder shaft, installed the Motor/Encoder with the 3 bolts.

Replaced the electrical connection and tighten the bolt.

Carefully put the yoke on the splines of the front shaft and nut. This is when I realized the transfer case is in gear, because the yoke would Not rotate.

Torqued the front shaft nut to 150 ft lbs per Alldata.

Reattached the front propeller shaft universal joint.

Reattached the negative battery terminal

Turned the ignition to ON and the 4WD HI light was on.

Pressed the 4WD HI switch and you could hear the mechanical shifting and the 4WD HI light went off, checked the propeller shaft which rotated freely.

Started the vehicle, put it in gear to back it down the ramps and a little ways back.

Tested the 4WD,
Pressed the 4WD HI – mechanical shifting and light – moved the blazer forwards and backwards – it was in 4WD HI
Pressed the 4WD LO – mechanical shifting and light – moved the blazer forwards and backwards – it was in 4WD LO.
Pressed the 4WD HI – mechanical shifting and light – moved the blazer forwards and backwards – it was in 4WD HI
Pressed the 4WD HI again – mechanical shifting and NO light – moved the blazer forwards and backwards – it was in 2WD HI

Checked the transfer case fluid level with a L shaped piece of wire and was found to be 1/8 inch below the add plug hole, so considering the small amount lost when the yoke was removed, it had not been leaking any.

Thanks for all the helpful info.

I’ve got 4WD AGAIN!

 

Isn't that an awesome feeling? I did that job on my wife's '93 Jimmy in November. I was thrilled when I got everything together and it would actually shift into and out of 4WD. Congratulations!

Also, thanks for the excellent write-up of the job. Hopefully that will help others in the future.