5.3 to 6.0 swap: Transfer case problems

Hey all,
I'm new to this forum and looking for some help. I recently swapped out my 5.3L for a 6.0L in my 2003 silverado 1500. I basically did a straight engine swap, keeping the 4L60 trans and transfer case. I have a friend who used HP Tuner to flash the 5.3 computer to a 6.0 and tune it all up (the thing runs like a animal now!).
The only problem I'm having is the transfer case is stuck in 2wd and the service 4wd message is on. I took it to my dealership to run the DTC's and here are the codes they found:
C0300: rear propshaft speed sensor malf
C0305: front " " " "
C0306: Motor A/B circuit malf
C0321: T case lock circuit malf
C0327: Encoder circuit malf
C0359: 4LO circuit malf
C0374: General system malf
C0379: Front Axle control circuit malf
C0550: ECU malf :confused:
B0790: T case neutral indicator circuit malf
U1000: class 2 data link malf
B2725: mode switch circuit malf
U1301: class 2 comm circuit low voltage

Needless to say I was a bit overwhelmed. I've been checking for smashed wires, good grounds and have made sure the transfer case motor/encoder is good and have found nothing. I also don't believe my TCCM has gone belly up either. My truck had the option of Auto 4wd with the 5.3L and I believe the 6.0L did not have that option which is where I think my problems are comming from.

Could the problem be between the main ECU communicating with the TCCM? Do I need to get a TCCM that will work with a 6.0L computer tune or is this something that I can fix using HP Tuner? Any help would be great and I'm looking forward to being a part of this forum!

Thanks

wow this really sucks for you... i hope u get this fixed! i know i would be bummed out if this happened to me ,,,, doing all the work and have all those problems...

best of luck to you! i hopewhen i do this same swap (LQ4) i wont come across all these problems!!!

Am sure some one on this forum will know. or have a ballpark idea

Lot of codes there.

Somehting's not plugged in or grounded.

I'm sure Nate will chime in and have some words of wisdom.

I swapped to a NP241, 246 is out with all the goodies on it. Let me know if you need anything.

I've check the grounds and traced the wire paths multiple times so i'm fairly certain its not that. The ground for the T case is under the driver door, we never pulled it but I will clean it just in case. The only thing I can think of now is to try replacing the TCCM but its kinda the last thing I want to do since its expensive.

Have you tried flashing the stock tune back on it to see if that changes anything?

Hopefully someone will chime in, but wouldn't it be pretty much a direct swap 5.3 unplugged and out and 6.0 dropped in and harnessed up, done deal? I'm thinking it would have ran on the 5.3 tune, correct me if I'm wrong....

Sounds like it is not comunitcating back and forth like you said, could simply be a bad connection or the tune?

Subscribed anyway as I'm looking at a 6.0 swap in the future!

By the way welcome to the site....

The 327 is the only common code and it's caused by the sensor inside the encoder. Sounds like the "tuner" flashed in a real 6.0 truck VIN from another tune or truck instead of just making the spark and fuel adjustments you needed for a motor swap. There is no way all that stuff is caused by an engine swap and if there was a TCCM problem or a problem with the TCCM power or ground you would not have been able to get the codes out of it...

Where are you located?

Quote:

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Originally Posted by GasGuzzler

The 327 is the only common code and it's caused by the sensor inside the encoder. Sounds like the "tuner" flashed in a real 6.0 truck VIN from another tune or truck instead of just making the spark and fuel adjustments you needed for a motor swap. There is no way all that stuff is caused by an engine swap and if there was a TCCM problem or a problem with the TCCM power or ground you would not have been able to get the codes out of it...

Where are you located?

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Thanks all for the advice!. The tune was done correct. The computer is still the 5.3 and like you said only the spark, fuel, and shift timing was adjusted. I am going to ohm out the shift buttons to rule out that. I'm sure its something ridiculously simple, SO FRUSTRATING!
Lol, I haven't been able to try a 4wd launch yet. I can't get the tires to hook up til 3rd gear cause my ass end is so light:naughty:!

I'm located up in northern Idaho. Moscow to be exact.

Looking again I must add that the B2725 is common too...that's the switch in the dash. The U1000 and U1301 are problems too....those are communication codes.

Hello all again! Been a while since I updated this post but I finally figured out why my 4wd hasn't been working. After checking all the wiring, the shift motor on the t-case, the dash button and finding nothing, it came down to the TCCM. I picked up a used one from a junkyard ($75 rather than a new one from the dealer for $307) off a truck that was similar to mine. Installed it and now it shifts! Although I think I still need to take my truck to the dealer to get the TCCM re-flashed.

I don't really know how this happened in the first place. Some how during the engine swap the TCCM got fried is the only explanation.