Chevy & GMC Vans

And she is alive!!!! No trouble shooting ..... no issues!! Just 4x4 excellence

Ryan

Wait are you saying that once you connected F7 on the TCCM to the VCM (thing in board of battery underhood) that 4lo started working??

And she is alive!!!! No trouble shooting now issues!! Just 4x4 excellence

Awesome =D> Now I feel a little validated!
Enjoy!!

I studied and studied and studied this forum..... I struggled following it in forum version so then I typed up the outline...... (which with Racrx7 I will update with some of my own thoughts to clarify a few of the steps) I then followed it to a freeking T. I ohm tested every wire that I installed from end to end. I did ask a few questions along the way, especially about TCCM to PCM connection (which will be added as step 5 to the wiring instructions rather than leaving it in the Q & A at the end of the document)

I guess now it is time to update my signature with NP236 4X4.

Ryan

Racrx7, have you determined whether it is best to drive from day to day in 2WD and conserve the encoder motor, clutch packs, and the axle disconnect emulator relay or drive in AWD as we all did before the conversion since we don't have the disconnect?

Ryan

SG, I always leave mine in 2WD on dry roads, and switch to 4WD auto if I get caught in rain. This can be done on the fly with no issues or adverse effects on any of the system.

Wait are you saying that once you connected F7 on the TCCM to the VCM (thing in board of battery underhood) that 4lo started working??

Trip south, The wire from the TCCM to the VCM, PCM, ECM, is only to correct the transmission shift points when in 4LO. Mine shifted into 4LO WITHOUT this wire being hooked up. The transmission just didn't shift correctly until I made the connection. That being said, the '99-'00 model with the 4 plug VCM looks to share this connection along with the front axle disconnect emulator circuit. so its possible this could be causing issues for some trying to make this work. It is imperative that the front axle emulator circuit, along with all other circuits, be correctly wired or the TC will not shift into 4LO.

Just to throw this out here, for those that may be floor testing all this before transferring into your van, make sure you leave the encoder motor ATTACHED to the case. If you apply power and try to actuate the encoder motor OFF OF THE CASE, toss it. Its now trashed. The hall effect switch plate inside will over stroke and become damaged.

And also run a decent sized ground wire to the TCCM case. The encoder motor reversing relays inside of the TCCM use the case for the encoder motor ground

I have spent the last 3-4 days just beaming that I got this running....,, I however can't escape the thought that all I did was follow great directions from racrx7 and captain crunch. Your time and effort to put this together and document how you did this is just amazing..... I would have never been able to do this if left to my own talent.

I can't wait to head to the mountains this weekend!!

Thank you!

Ryan

Ok so I haven’t gotten much done in the last few months but now it’s time to dial in the switch. I have chosen the long switch and am placing it inside the glove box.... I haven’t worked out all the details but I have mounted a 2 inch long piece off 1x1 aluminum and then attached the switch to that. Once the I’ve box is closed you can’t tell anything is different than stock I have arrived at a problem though..... this switch uses a matching 4 wire plug but a different 8 wire plug. I got the correct plug and assumed that the wire locations /pin out would be the same as the blazer. I set it up as such and it doesn’t work at all. I have Ben getting 2 if every electronic part so I was able to just plug in another to test..... no luck.

This is the plug I am working with
The stock wires for this switch don’t all match in color and the ones that do match are in very different locations.

I will keep working on this and any one else’s thoughts are appreciated. Or the wiring diagram for the 99 and newer suburbans that have this switch.

Not sure why the blog is rotating my pictures I will keep working to figure that out.

Thanks,

Ryan

Very clever location for switch.
I may just mount my switch on a diagonal bracket on the sloping part of the lower dash trim to the right side of the steering wheel.

AP

Ryan, unfortunately that later model switch is wired up differently than what you were using. It will work, as I had a later model blazer switch originally, but for some strange reason, GM threw a curve ball on the wiring. I'm outta town right now, but believe I have the wiring diagram your asking about at home. You'll have to look at both diagrams side by side and see where the pin out was changed. It is doable.
Andre

Ok so here is what I figured out laying in bed last night. Looks like I am down to 2 unknowns but please feel free to correct me if I have any of this wrong.

Attached are both the wiring diagram that we have been working with and the 2003 Suburban switch with AWD

Red are the ones I don't know.

Blue or Black 8 pin connector = C1
A = unknown
B connects to TCCM E3
C connects to TCCM F3
D = Empty (known because this line is empty on stock wire harness and others i can find pictures of)
E connects to Body control Module
F = unkown
G connects to Fuse Block
H Connects to TCCM F16


White / Clear 4 Pin Connector = C2
A connects to TCCM F14
B connects to TCCM E4
C connects to TCCM F1
D connects to TCCM F2

Got it, will post details soon for anyone else wiring this switch.

Ryan