TCCM control NP246?

[MaroonMonsterLS1]

Has anyone tried a 4l80e swap and just used a NP246?
Envoy Denali for reference...4 position switch
They are 6 bolt, so they will mate to the stock 4l80e t case adapters. And 32 spline inputs are readily available and fairly cheap.
I want to retain the selectable 4wd

Wondering if this will "plug and play" with the stock TCCM? Both 4 position switch style transfer cases. Both use the same harness plug/connector with the same pinout even.
I guess the only question would be...is the encoder position signal the same between the two? If so, I think all would be fine.

Has anyone tried this yet? If not, I'll do some leg work and report back

 

[mrrsm]

THIS is from "Brett with Shift Rite Transmissions" writing up an Original Article over at TBSS OWNERS on this very "On Topic" subject:

08 tbss 4l80e awd np246 swap

www.tbssowners.com

Suggestion:

Copy Paste Brett's "WALL OF WORDS" from THIS PDF into a WP and make the requisite edits to make it more *digestible"...

 

[xXxSilveradoxXx]

I've looked into it some. Don't know what you're planning on doing with the rig, but there are a few different routes you could take.
-You can use a Silverado SS AWD transfer case. There's a guy on Performance Trucks that make a 32-spline input for that case.
-You can use the stock transfer case with an adapter ring and either respline the input shaft on the transfer case or respline the output shaft of the 80E.
-You can attempt to swap in the NP246. Bolting up the 246 to the 80E will be no problem. The issue will arise with the wiring. The Trailblazer uses a 3-volt signal wire to the selector switch, whereas most all other GM stuff uses 5-volt. The Trailblazer also has different drive options to select from. I think your best bet to utilize the 246 would be to swap the case, case controller and the selector switch and attempt to run it as a standalone system.
Personally, if funds allow, I'm hoping to swap in a L92 and either a 6L80E or 6L90E and use the stock transfer case. My plan is to use an adapter ring and to respline the output shaft of the transmission or input shaft of the transfer case.

 

[MaroonMonsterLS1]

My hope/goal is to use the factory TCCM and just swap the t case.
The selector switch will be a non issue because the TCCM is "used to" the switch voltage.
I need to confirm encoder motor functions.
If the encoder on an np246 gives the same feedback voltage for each position, then it should be no biggie I'm thinking.

i.e. if 2wd mode gives an encoder voltage of say 2.4 volts on the envoy...and same on a gmc pickup with 246

and 4wd mode gives encoder voltage of say 3.1 volts for both
etc

then I'd *think* the swap would be a direct fit.
If that's NOT the case then we'll have to dip into the bag of tricks to get something to work.

p.s. those are made up voltages, I need to get the scanner on both vehicles and just give it a quick test.

 

[mrrsm]

This Document provides some TCCM Electrical Voltage vs. Ohms Readings and other Diagnostic Data that may prove helpful in your project:

A Guide to the NV 246 Transfer Case - Transmission Digest

This transfer case is one of the so-called “automatic transfer cases,” or “active transfer cases.”

www.transmissiondigest.com

 

[TJBaker57]

The Trailblazer uses a 3-volt signal wire to the selector switch, whereas most all other GM stuff uses 5-volt.

I have something like 5 or 6 TCCM from TrailBlazers and none use a 3 volt switch power source.

5 volts is sent out from the TCCM and passes through various resistances in the switch to return from as low as 0.7 volts in neutral position to 4.46 volts at the 2Hi position.

 

[TJBaker57]

those are made up voltages, I need to get the scanner on both vehicles and just give it a quick test

I have a 2002 TrailBlazer and an 05 Yukon.

For the TrailBlazer I have extensively researched these voltages and their ranges.

I have a handful of TCCM and a Tech 2 and have bench tested the voltages for the TrailBlazer switch and the encoder, finding the entire ranges determined by the Tech 2 to be each position. (Did that make any sense?)

I even found a range where the Tech 2 reports a "2 Low" position!! And by the way, through some trickery I once or twice successfully got into that range!! Just a proof of concept sort of thing.

For the TrailBlazer I can post the range of encoder return voltages for each mode.

Now I don't work as much with the Yukon, I think it might have that NP246?? Has the 4 button for certain. I'll have a look.

If I still have the old encoder ring I replaced some years ago I should be able to bench test the ranges there also.

 

[TJBaker57]

Used my Autel AP200 on the 2005 Yukon a couple days ago to spot check the voltages from the encoder at various modes. Have not looked into the voltage ranges yet, just the readings returned from each operational position.

They are different than the TrailBlazer. I didn't take notes this time but I remember 2Hi was 2.98 volts on the Yukon and is more like 2.73 volts in the TrailBlazer. 4 Hi was also a higher voltage in the Yukon vs the TrailBlazer.

 

[MaroonMonsterLS1]

I checked my 07 envoy denali against an 05 gmc sierra 1500 with 246. 4 button pushbutton selector on the truck.

Unfortunately it looks like some more work will need to be done to make the swap "easy"

 

[xXxSilveradoxXx]

I have something like 5 or 6 TCCM from TrailBlazers and none use a 3 volt switch power source.

5 volts is sent out from the TCCM and passes through various resistances in the switch to return from as low as 0.7 volts in neutral position to 4.46 volts at the 2Hi position.

You are correct that the TCCM doesn't use 3-Volt. I knew they were different voltage, but mistook the volts. According to someone who has done the swap, the Trailblazer selector switch uses 5-Volt signal as opposed to the 246's 8-Volt signal.



Now with that said, re-reading through the thread, the OP ran a shop and could be misleading people wanting to do the swap themselves.

nrrsm posted earlier in this thread with a diagram showing an 8-Volt reference for the 246, and according to the shop manual diagram, it shows a 5-Volt reference for the selector switch on the Trailblazer.




Not sure what would be easier, using the Trailblazer switch to control the 246's TCCM or using the Trailblazer's TCCM to control the 246.

 

[mrrsm]

It may also come down to whether or not the PCM will be able accept some variation on the Re-Calibration of the PCM , BCM and TCCM that meets with the DC Voltage differences. It is quite an interesting problem... for sure. I wonder if any TSBs have addressed this issue.

 

[TJBaker57]

Trailblazer selector switch uses 5-Volt signal as opposed to the 246's 8-Volt signal.

FWIW, I have run across a few instances where the wiring diagrams have incorrectly shown an 8 volt reference where in fact it was a 5 volt reference. It is my belief they are both 5 volt references in reality. My 2005 Yukon is most assuredly a 5 volt reference at the TCCM/Shift motor.