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Your TCM is probably bad. We see at least 3~4 Frontiers, Xterras and older Pathies every year with seemingly-dead CAN buses. When the in-tranny TCM's fail, they often either pull CAN-H flat or go into a locked-loop transmission that won't let other devices get a word in. In the former instance the bus will die completely, in the latter a few devices will show up but many will be missing. Remove the umbilical from the tranny and I almost guarantee everything else on the truck will wake up.

I'll add to this, about 4 years back we saw a rash of brand new TCM's out of Nissan's Memphis warehouse that wouldn't program and wouldn't come up on CAN. It turned out they had no bootloader program inside the TCM. We ordered one from the Dallas warehouse after 3 unexplained clinkers and the problem was solved. So even if your TCM is brand new, the chance of it being bad is small, but it isn't 0%.
 

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There's only one electrical cable going into the tranny, it's on the righthand side near the shift linkage. Just pop it loose and re-scan the vehicle. If the CANbus suddenly "wakes up" and all the other stuff starts talking, then your TCM is defective. If you can get hold of a SM then the LAN section has the CANbus wiring diagrams and explanations of how the whole thing works. It's basically just a messaging system between the important computers in the car. It uses two wires, CAN-L and CAN-H. Some stuff can still communicate if CAN-L is compromised, but if CAN-H goes down then it disables everything. Bad TCM's usually take down CAN-H, so it looks to a scanner like the whole bus has crashed.
 

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PS - If your TCM is new then it will need to be programmed. Nissan stopped issuing pre-programmed ECM's and TCM's several years ago. However, an unprogrammed TCM should still show up on a scanner and allow the truck to start, because it should have an abbreviated starter program called a bootloader that permits it to talk to the CANbus. It can't run the tranny and if you try to drive that way it will be limp, but it should show up on CAN. That's what allows it to be loaded with a permanent program that's correct for your truck. The dealer probably needs to do that for you, very few scanners outside a dealership will be capable.
 

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If the port is talking (and showing all systems in the truck) then the TCM is alive and isn't causing the issue. When the bus is dead or not all systems are showing up, that's usually the TCM. So you may have a different issue like an IMMU. I don't think an '07 would still use the old "fixed code", but I suppose it's possible. Have him try 5523 when initializing BCM.
 

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If it's a fixed code then you don't upload anything, you just put the BCM in NATS mode and the code is 5523. The trucks were always several years behind the cars in terms of NATS hardware, so it's possible you have one of those.
 

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For pre-2008 vehicles we use a Nissan Consult2 here at the shop, I have no idea how you'd do it with outside hardware. With the C2 you just skip the code upload and go straight to BCM initialization.
 
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