The only port on the transfer case that does not have a connector to it is the one in the photograph that I shared. The 233 only has the connections at the encoder motor and the output shaft housing. The color of the wires I proposed to hook up are purple/ white and green/ black. This photograph of the unconnected connector is I believe the c116 connector. It's the connector I planned to add an additional 12 in of wire to.




C116

 

The Purple/wt and green/blk are definitely the speed sensor wires. I'm going to have to agree with you on the C116 connector, unless this is part of a 2WD harness that used to plug into a speed sensor at the right rear of the transmission. In any case, extending it back to a single TC speed sensor should work fine. Can't say what speed sensor will work for you. Do they look different inside where they mount? You could dummy it up and read the vehicle speed on a scan tool if you don't have a speedo yet.

Is that wiring harness in the photo up against your exhaust?

 

Thanks for the confirmation on the connector. The videos I have watched on the speed sensors make it look like the internals are all the same. I wil find out firsthand tomorrow.

No the harness is about 5 inches away from the exhaust, but I appreciate you keeping an eye out for other potential problems!

I haven't started digging into what happened to neutral yet. I plan to pull the neutral switch off the transmission again. and see if that makes any difference getting the wheels to stop turning. when the 'clicks' on theshifter would indicate that I am in neutral.

You may be interested. I replaced all of the dash guages with a tablet computer using obd-2 input into a Realdash application. I still don't have all of the bugs worked out there yet, but I have indications from RPM, temperature, charging, fuel gauge. I haven't been able to get a transmission gear reading on the Realdash yet. I think that is because I need to replace the transmission connector that was very brittle and got damaged in removal.. I have another connector ordered, If that doesn't fix the problem, I'll have to keep looking. ,

Les, You have been very helpful. I really appreciate all that you have done for me. I hope I can pay it forward somehow.

 

Just keep me posted on this project. It raises some issues that are interesting to me.

What about when the wheels are on the ground. Do you feel it is still in drive? Do you have a separate scanner that can read gear position as seen by the PCM? The PCM has to know the trans selector position in order to control the electronic trans solenoids. If you like I'll see if I can figure out the trans input wiring to the PCM.

 

Here's some schematics for the transmission. Not absolutely everything, but may be useful. If you need anything else, please specify.

 

I have been a bit under the weather and haven't posted an update.
However, I have good news to report. Transfer case is in and has been operational. (The lights went out on the switches, so I still have some troubleshooting to do.I can use the troubleshooting procedure that Les sent to me early in this transaction.)
Nonetheless: 1. As Les suggested, the movement of the axle in neutral was not a problem, The wheels rotated when they were off the ground, but when I took out the jackstands, there was no movement in neutral.
2, Apparently the used transfer case I boughtwas from an older model k series. The speed sensors from the transfer case that I removed did not fit. I kept the speed sensor and replaced the connector with the appropriate connector and now I am getting a speed indication on my OBD 2 reader. So it seems that the speed sensor on the old transfercase is compatible with the later ECU.
I am not getting a gear shift lever position indication to my OBD2. Does anybody know if that information is available from OBD-2 on the Chevy Blazer?

 

yes, but scan tool has to support it. I know that Dash Command for Android among others do (see below). I thought Car Diagnostic Pro did as well, but I'm not seeing it.

 

I found it in Car Diagnostic Pro (which is a cheaper and more universal option).

 

Update on the project.
Transmission, transfercase and front wheels are all engaging, Thanks to all for the help with the project.

I have been having problems with intermittent operation on a few things. The first time I took it out, it wouldn't shift into 1st when the shifter was in the drive position. It was throwing a C0225 code (If memory serves) which was a problem with the first shift solenoid. I had replaced this solenoid when I installed the transmission many months ago, and I wan't willing to open the pan on the transmission again right away. The possible solutions for the error code included transmission fluid levels. And because the transmission fluid is all new and fresh, I thought I would try drive it around a while and just see if the warnings from some sectors about replacing transmission fluid could have some validity.

I drove it around the block and out on the road to make sure it was sufficiently warmed up.. And soon the shifting was smooth from stop to 60+ MPH. I laughed a triumphal laugh and drove it around some more.

I let it sit for a few hours and went out for another test spin. Although I didn't put the OBD2 reader back on, it appears I am still having the same problem. If I drive for 20 minutes, it starts shifting smoothly again.

I figured out why the lights on the 3-button switch weren't; working. There are some loose connections either in the switch or the connector from the harness. I will have to work on that right away. During one of my test runs it sounded like the front wheels were trying to engage, Z-z-z-z-z--z-z-z- klunk. That's got me a little spooked.

The speed sensor seems to be working just fine.

Anybody out there have any insights about solving these other issues?

 

In case anybody else has some interest. I have been reviewing the wiring diagrams sent by Lesmyers, They showed a connection between the 1st gear solenoid and the 4wd switch.
I found that the 3 button 4wd switch had a loose connection. As soon as I fixed the intermittent, the c0225 code cleared up.
I am losing a little power still due to a Cyl 1 misfire. That seems to clear up after I have driven it a while. It makes me concerned that I have a head gasket problem. I have only put 100 miles on the new heads, I am keeping an eye on that situation.