Remove/disable TCCM without Service 4WD/AWD light

timg

Original poster
Member
Sep 9, 2012
8
Does anybody know how to remove/disable the TCCM without triggering the Service 4WD/AWD light? I tried unplugging the module and pulling fuse 8, but both lit the Service 4WD light. I was thinking about swapping my transfer case (NP4 - NVG 126) for the transfer case from a TBSS (NR9 - NVG 120) which does not use a TCCM. This has to be simple, because all of the 2WD and TBSS AWD models work without a TCCM. Thanks.

Tim
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The Service 4WD light goes on whenever the PCM fails to communicate with the TCCM. The PCM is in charge of this function. A GM Tech II tool in the hands of a dealer (or experienced independent mechanic) can change the vehicle's option configuration to tell the vehicle it's a 2WD model and for the PCM to quit looking for the TCCM.

But then you'll have to make sure the front axle actuator is extended to engage the splined disconnect before you unplug it, because without the TCCM, you went the splined disconnect to be permanently engaged.

Driving behavior is likely to be compromised unless you also change out the rear axle to the SS model limited slip. The driveline may not behave well with a Torsen in the transfer case and a G80 locker or an open carrier in the rear.

Interesting project, though. What is the benefit you're hoping to get?
 

timg

Original poster
Member
Sep 9, 2012
8
I already have a LSD in the 8.6" rear, but have purchased 3.42 gears and a 9.5" Truetrac differential. I'll probably pick up a 9.5" rear from a junkyard soon. Since I already have the LS2 installed, I've been upgrading everything else. With the upcoming new transmission, supercharger, headers, heads, cam, etc., I figured that the NVG 126 might not be too happy and since the rest of the mods will require redoing everything, it would be an easy time for a swap.

Tim
 

timg

Original poster
Member
Sep 9, 2012
8
If it's controlled by the PCM, I wonder what would happen if I did a write entire with a TBSS OS via HPTuners.

Tim
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Eric is the expert, but I think you should have gotten an SS PCM from the donor vehicle if it was a recycled engine. You need his help at this point.

Why not 4.10 gears like the SS for faster off the line? Or is your mission just to go fast, not get-to-fast-fast? :undecided:
 

timg

Original poster
Member
Sep 9, 2012
8
Didn't need the SS PCM, it was a brand new crate engine (found it on Superior Chevy's website as their daily special for $2k while I was working in Siberia). It's been running 2.5+ years and almost 30k miles now. The initial tuning was incredibly easy. The main reason I haven't tried flashing a TBSS OS onto it is that I don't want to use more HPTuners credits unless I need to.

Basically, I have a ton of mods coming up. 99% of the parts are purchased and sitting in the basement just waiting for me to finish my S2000 rebuild to be able to take my 9-7X offline. Since I'm doing a 6L80E swap, the 3.42 gears mean better cruising with 1st and 2nd gear still steeper than a 4L70E with 4.10's. The transfer case swap isn't something I have to do and is something I may not attempt. It and the rear axle are the only two parts I haven't purchased. I just thought that since I would probably pull the engine, transmission, and rear end for all of the upcoming modifications (and need to split the t-case to replace the input shaft for the 6L80E), it might be a good time to swap the transfer case as well.

Tim
 

jrSS

Member
Dec 4, 2011
3,950
Some ss guys are going to the 3.42 gears simply for better mpg's...but I won't ..I like the awesomeness of the 6.0 with 4.10 gears.
 

timg

Original poster
Member
Sep 9, 2012
8
jrSS said:
Some ss guys are going to the 3.42 gears simply for better mpg's...but I won't ..I like the awesomeness of the 6.0 with 4.10 gears.

I wouldn't recommend anything other than 4.10 gears for the LS2 with a 4l70e ( unless you have a TVS2300). Even with 3.73's, the 1-2 shift sucks for daily driving. Either you stay in 1st and rev the heck out of it, or drop to 2nd before the engine really makes any torque.

Tim
 

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