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Again, Thanks for the direction. As a result of LesMyer's help, I was able to learn a few more things.
1 There are significant differences between the wiring harnesses used for the 3-button and 4 button transfercases.
2..At this stage in my build it was going to be much simpler to replace the transfercase than it was going to be to replace the wiring harness. I have ordered a replacement (Used) TC.
I am now going to learn by experience if the drive shafts are similar or if I am going to have to resize/re-spline the custom drive shafts I had made for the 4-button TC I am going to replace.
Success! I was able to replace the transfer case with a 233.. LesMyers was right about the driveshafts. They fit correctly. The buttons light up on the 3-button switch. The transfer case motor works. I can shift in to forward and reverse. The only problem I have now is that I can't find the connector that will reach to the speed sensor on the transfer case shaft.
It would have given you guys with the right tools a laugh to see the way I finally was able to lift the transfer case into position. The tool rental place had a transmission jack, but it wasn't going to be available for a couple of weeks. I didn't want to wait that long. There wasn't enough room to slide under the blazer with the TC on my chest. I finally used two ratchet straps to lift it off the ground and position it roughly so I could slide under and 'bench-press' the TC into place.
,Les do you have a diagram that shows the correct connector? It looked like it should be the connector that is along the same portion of the harness as the transmission connector. But it won't reach the speed sensor and doesn't have the right connector on it.
Success! I was able to replace the transfer case with a 233.. LesMyers was right about the driveshafts. They fit correctly. The buttons light up on the 3-button switch. The transfer case motor works. I can shift in to forward and reverse. The only problem I have now is that I can't find the connector that will reach to the speed sensor on the transfer case shaft.
It would have given you guys with the right tools a laugh to see the way I finally was able to lift the transfer case into position. The tool rental place had a transmission jack, but it wasn't going to be available for a couple of weeks. I didn't want to wait that long. There wasn't enough room to slide under the blazer with the TC on my chest. I finally used two ratchet straps to lift it off the ground and position it roughly so I could slide under and 'bench-press' the TC into place.
,Les do you have a diagram that shows the correct connector? It looked like it should be the connector that is along the same portion of the harness as the transmission connector. But it won't reach the speed sensor and doesn't have the right connector on it.
Unfortunately I have given you all the location diagrams that I could find, and mine is a 236 transfer case. Need someone who has a 3-button 233 to go look and see where the wiring to the speed sensor comes out of the harness....................... Who here can do this for us? Maybe snap a few photos?
Compare what your wiring harness looks like at the transfer case to these diagrams. Maybe you have 4-button wiring there?
There are three speed sensors on either TC. Front Prop Speed, Rear Prop Speed, and VSS. Maybe your connector is for a different sensor - one of the others in the set of 3. On the 3-button the wiring coming out right before the Encoder motor is for VSS. But on the 4-button, the wiring coming out right before the main encoder motor connector is for Front Prop Speed. If you have the 4-button TC harness, could be why your connector is different.
Also, are you aware that 3-button does not use the electrical vacuum solenoid on the firewall? There is a mechanical vacuum switch on the transfer case that controls the front axle lock-in.
Don't worry you are making progress. Looks like the controls and TCCM is working fine. But you may need to source a 3-button TC jumper harness if you have what I think you do (or at least do a lot of rewiring there). Let us know what you have!
OK....... C108 for the NP8 (4-button) TC jumper harness has 16 wires. C108 for the NP1 TC jumper harness (3-button) only has 8 wires. The connectors where they attach to the body harness are different, but the 8 circuits in the NP1 are the same in both systems as far as function and wiring color. To complicate matters, position of different sensors on the TC are different between the two - so its not just a plug in thing to use a 4-button harness on a three button TC.
See attached document about 1/4 of the way down. Connectors go in order.
So, if indeed you do have a 4-button body and 4-button TC jumper harness, your body harness will not have the correct connector to hook up to a three button TC jumper harness. But if you get a three botton jumper harness you could easily splice the two together, color for color on the downside of the existing connector somewhere before the TC. Just leave the extra eight wires unattached and taped over. Don't forget to solder everything - current draw is pretty heavy on the TC shift motor. AFAIK this would work, as long as the computer doesn't think it has a 4-button TC and complain about not having certain inputs from the TC.
Alternatively you could try to modify a 4 button TC jumper harness to reach things on a 3-button transfer case.
All of this of course is predicated on which wiring harness you have in your vehicle. So figuring that out is imperative before proceeding!
Thanks for the heads up. I have removed the vacuum solenoid and run a vacuum line from the transfer case to the actuator. I haven't started troubleshooting why the front axle isn't engaging yet, I may have a vacuum leak.
I will send some photos. My transfer case doesn't look like either of the TCs in the attachments. It has one 7-pin connector at the TC motor and a speed sensor at the end where the driveshaft connects.
I bought a used transfer case from, ebay and I am afraid I don't remember what year it came from. The engine is from a 2000 the 4l60E transmission is from a 2001.
I am making good progress, but i enoucontered a new wrinkle. Since I replaced the neutral safety switch, there is no neutral gear. When I shift the gears go from park to reverse to dr. I have everything up on stands so the wheels can turn freely.
I am confident that the wiring harnesses are matching up with the items trans and transfer case. I've even got the the front axle to engage like it is supposed to. ( I found an unterminated T in the vacuum line to the actuator,) The 3 switch unit functions like I expect it should. At this point this is the only unterminated connector. It is on the transfercase output shaft housing.
Considering its location, I think it must be a speed sensor. (In the photo below). The connector is unlike any other connector on the variety of harnesses that I have so I suspect that someone put in a speed sensor from some other make or model.
The .diagrams you sent have been helpful to identify the wires. Right now I am thinking that I will replace the speed sensor with a speed sensor from the TC i just removed so th econnectore is correct. and splice in another 12 inches of wire on C108 connector and connect it up. I would appreciate your opinion if there is anything that could bite me in the backside with that plan.
What sensors (not encoder motor) are already hooked up on transfer case and what are the wire colors hooked up to them. What are the wire colors for the wires you are proposing to hook up to this new sensor? Please advise and I will try to figure it out. Thanks!
