Allison 6sp: Lbz 2wd to 4wd questions!

Trip450

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Aug 25, 2019
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What’s up everyone. So my truck is a lbz 2wd. So I’m going to be purchasing the wfo sas kit. But won’t be for probably another few months. But I have a few questions. I have bought trans tcase body harness and dash harness off a 4wd. My question is if I put everything on my truck will I still be able to drive it in 2wd with the 4wd transmission and tcase on the truck with the 2wd ecm and tcm? Just want to make sure my truck will still be driveable haha
 

Trip450

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Aug 25, 2019
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Lbz 2wd to 4wd conversion ecm questions

What’s up everyone. So my truck is a lbz 2wd. So I’m going to be purchasing the wfo sas kit. But won’t be for probably another few months. But I have a few questions. I have bought trans tcase body harness and dash harness off a 4wd. My question is if I put everything on my truck will I still be able to drive it in 2wd with the 4wd transmission and tcase on the truck with the 2wd ecm and tcm? Just want to make sure my truck will still be driveable haha
 

Bdsankey

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Feb 1, 2018
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Stick with one post asking the same questions. This is the third post I've seen on this topic. One in introductions, one in tuning/logging/gauges, and this one in builds. Making the post in multiple locations will not get you an answer quicker. Your other post in tuning/logging/gauges should get you the answers you're looking for in regards to potential issues via the ECM/TCM/BCM.
 

Trip450

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Aug 25, 2019
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Thank you. What about the tcm I don’t want to use 4wd yet
 
Last edited:

JoshH

Daggum farm truck
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Stop spamming the forum with the same question. I caught one and deleted it before anyone commented.
 

2004LB7

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Dec 15, 2010
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Norcal
The only thing I remember about some others who have done it is having trouble in 4Lo. Something about wheel speed being sensed by the ABS being different then what the computers think it should be. Unless you have a way to tell it it is in 4lo. Otherwise in 2hi or 4hi it was fine
 

Bdsankey

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Feb 1, 2018
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Neenah, Wisconsin
The only thing I remember about some others who have done it is having trouble in 4Lo. Something about wheel speed being sensed by the ABS being different then what the computers think it should be. Unless you have a way to tell it it is in 4lo. Otherwise in 2hi or 4hi it was fine
Would an OS change fix that? I've never tried converting them over either from 2wd or from ifs to sas.
 

2004LB7

Active member
Dec 15, 2010
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Norcal
I think it was from being unable to send the 4lo signal down the can bus or whatever it used to tell the modules it was in 4lo. Unless you hooked up all of the components, switches, modules, etc 4lo was pretty much a no go unless you are fine running with ABS and other lights on

I think all the BCM, TCM and anything else involved is programmed with the 4WD calibration. It just never goes into it without all the required hardware

There are others here that understand this part much better than me. We should wait for them to chime in
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
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Central OH
Not sure if 06+ is different, but when I 4wd swapped mine, I just hooked up the harness. Didn't have to reflash anything, just had to source the TCCM and hook it up. From what I remember, Ben said the calibrations are the same, you just have to run a signal wire for 4LO so the ECM / TCM knows
 

Trip450

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Aug 25, 2019
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I haven’t been able to get in contact with Ben he doesn’t seem to email back or answer phone calls. Would love to buy a harness off of him
 

TheBac

Why do I keep doing this?
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Apr 19, 2008
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You may be better off building your own or going to the boneyard and removing one off a junk truck
 

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