LB7 OS Swap for 4wd FROM 2wd

lockner13

Member
Aug 17, 2013
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Hey Guys,

What I have is an 01 CCSB 2wd DMAX/Allison truck that I swapped EVERYTHING from an 01 donor truck that was push button 4wd. It all works on my factory OS, but when in 4lo I get VSS code P05xx due to the speedometer not reading correctly because the truck doesn't know its had a ratio change. This was ALL plug n play minus the mounts on the frame and tail housing change on the tranny. Do I need to change my OS to a 6006 OS for a 4wd truck? Also, do I need to change the trans tune and if so what should be changed with it??
Any help would be appreciated!
Ben
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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ZEPHYRHILLS, FL
All tcm tunes are for a 4x4, so no need to change that. You might need to change the ecm os though due to the push button transfer case. I know I get the p0500 code in mine, but its because mine is a swap and has no other speed sensor input to check the vss against, so I shut the code off. Since yours is a push button, you may need to disconnect the 4 low input wire and front axle feed to the ecm since it is now getting those from the tccm over the databus.
 

lockner13

Member
Aug 17, 2013
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Ok THANKS! Ive been working on it slowly and just got efilive so I was hoping I could get it all straightened out now. You don't happen to have any good DSP5 tunes for a 6006 OS dou you? My truck has an lbz pump, new injectors, 4" MBRP exhaust, MBRP downpipe, S&B kit, race plug in the fuel rail, a FASS 150, & FASS filter delete kit.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,492
472
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Central OH
Shouldn't need to change the ECM tune like Ferm said. I thought Ben mentioned when doing a conversion, that just a wire had to be tapped into the tcm harness when 4lo is engaged.

Search here in the tune library, I'm sure there's some good street and tow tunes for lb7s. Should also be info on rescaling the fpr for the lbz pump.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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ZEPHYRHILLS, FL
All of mine is dsp2. I have a dsp5 at home I could send you for a stock trans, and change out the scaling for the lbz regulator. Sounds to me like a wire got forgotten(either added or leftout) causing your p0500. I know mine does it because it doesn't have the abs there to verify the speed against in 4 low, but a regular truck shouldn't have that issue. I'm going to cut the 4 low signal to my ecm one of these days to take care of mine so I can re enable the dtc.
 

lockner13

Member
Aug 17, 2013
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All of mine is dsp2. I have a dsp5 at home I could send you for a stock trans, and change out the scaling for the lbz regulator. Sounds to me like a wire got forgotten(either added or leftout) causing your p0500. I know mine does it because it doesn't have the abs there to verify the speed against in 4 low, but a regular truck shouldn't have that issue. I'm going to cut the 4 low signal to my ecm one of these days to take care of mine so I can re enable the dtc.
Thanks for the replies guys, ive been scratching my head on this for a bit now. All the harnesses and wiring literaly unplugged from one truck and into the next so I kinda had the wiring ruled out, but maybe i should take a second look. If you have some tumes i could use that would be awesome! I'll pm you. Thanks again!

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lockner13

Member
Aug 17, 2013
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Also, im not ssure if it matters or not, but do i need a 6006 OS thats for a California truck since mine came outta CA? The only thing ive seen noticeably different was the CA truck has the different glow plug controller. I hope someone can chime in on that one as I forgot to mention it originally.

Thanks again guys!
Ben

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DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
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Boise, ID, USA
The difference between the CA and federal tunes are the glow plug controller and EGR. CA has a better glow plug controller (IMO), but has EGR to contend with.

You can run a federal tune with the CA glow plug controller (I do), but EGR will not function. If the motor is from a CA truck, I'd run the CA OS unless you have deleted the EGR.

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lockner13

Member
Aug 17, 2013
44
0
6
The difference between the CA and federal tunes are the glow plug controller and EGR. CA has a better glow plug controller (IMO), but has EGR to contend with.

You can run a federal tune with the CA glow plug controller (I do), but EGR will not function. If the motor is from a CA truck, I'd run the CA OS unless you have deleted the EGR.

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Ok, well my truck is an early 01 and has ca emissions label, was sold new in ca but it has no egr system to be found lol. Maybe they didnt do egr on 01? So i guess i can use the federal OS then?

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Awenta

Active member
Sep 28, 2014
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CT
Is there a riser on the passenger side uppipe

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01 Sierra 4.8

New member
Dec 13, 2015
28
1
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Hey guys I'm doing the same 4wd swap on my lb7 the 2 wires that Come off the harness connected to the tcase trans and front diff. (Green with black stripe and purple with white stripe) where do I rewire them and how That's the last thing I gotta figure out before I do the swap... Truck I'm doing the swap on is an 02 can I use the push button harness and tccm out of an 03. If anyone could help that'd be awesome thanks
 

lockner13

Member
Aug 17, 2013
44
0
6
Hey guys I'm doing the same 4wd swap on my lb7 the 2 wires that Come off the harness connected to the tcase trans and front diff. (Green with black stripe and purple with white stripe) where do I rewire them and how That's the last thing I gotta figure out before I do the swap... Truck I'm doing the swap on is an 02 can I use the push button harness and tccm out of an 03. If anyone could help that'd be awesome thanks
Not sure on the wires, ill try and look though. Mine was a full wiring swap as needed. Im pretty sure that it has to be 01-02 harnesses ONLY as the 03 up used different wiring on alot of the stuff. I changed the dash harness, added the t case harness, installed the factory 4wd jumper connector to the vss from the trans harness to the t case harness, changed the tail housing on the trans and the output shaft, added proper bushings in the passenger side of the frame, welded the proper brackets on the drivers side frame and mounted all of it. All in all i probly had 25-30hr in it bits at a time. The push button should be fine, the harness should be an 01-02 and the tccm i think can be from any with 2500-3500 01-06 but dont hold me to that lol.

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01 Sierra 4.8

New member
Dec 13, 2015
28
1
3
Not sure on the wires, ill try and look though. Mine was a full wiring swap as needed. Im pretty sure that it has to be 01-02 harnesses ONLY as the 03 up used different wiring on alot of the stuff. I changed the dash harness, added the t case harness, installed the factory 4wd jumper connector to the vss from the trans harness to the t case harness, changed the tail housing on the trans and the output shaft, added proper bushings in the passenger side of the frame, welded the proper brackets on the drivers side frame and mounted all of it. All in all i probly had 25-30hr in it bits at a time.

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I just got the buttons on the dash tccm and harness I have all the wiring now just need to put it all together and do the rewiring. Getting the first big dump of snow right now 2wd doesn't really work good at all aha
 

lockner13

Member
Aug 17, 2013
44
0
6
The tccm harness should be a integrated part of the dash harness. Its not a bad job to do just take you're time and go about it right amd make sure to research it really good. If you have any questions just send me a msg and ill try amd help ya out all i can

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01 Sierra 4.8

New member
Dec 13, 2015
28
1
3
The tccm harness should be a integrated part of the dash harness. Its not a bad job to do just take you're time and go about it right amd make sure to research it really good. If you have any questions just send me a msg and ill try amd help ya out all i can

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I couldn't find the harness so I pulled it out of an 03 as well as a tccm i might put that in tomorrow just the 2 wires for 4wd low is bothering me and I'm not sure if there are 2 wires that go to the ecm. When I rewire them how do I do that
 

lockner13

Member
Aug 17, 2013
44
0
6
I couldn't find the harness so I pulled it out of an 03 as well as a tccm i might put that in tomorrow just the 2 wires for 4wd low is bothering me and I'm not sure if there are 2 wires that go to the ecm. When I rewire them how do I do that
Im not really sure on the 2 wires. Do you have any wiring schematics for it? If not i can get them for you.

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