[MasterBeefy]

I have an 07 Nissan Frontier and recently had to change the TCM, after replaceing both the TCM and all the Transmission shift Solenoids I had ended up (cherry on top) Losing the Key. (which is of course chipped). I ended up having a locksmith come out to program a new one (200 bucks on top of the already 220 for TCM and Solenoids) and when he tried to progam the key but the OBD ii Port wouldnt respond. No codes thrown, no message except from his computer that stated that the port wasnt responding. I checked the Fuses and none were Blown. When i Looked under the Dash at the port I seen the extra ports coming off the side of the wiring for the OBD ii port but after a little researching I figured out that at least two of them were for other options that my truck doesnt have. Its the Third port that i Found that bothers me. It looks as if 2 of the wires off the side of the harness that connecting to the OBD ii port have been spliced into and a smaller port is connected to those. I will post Pictures asap, but the third port wasnt connected to anything and I have found no other plug that it might go to anywhere under the Dash.

 

[VStar650CL]

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%.

 

[MasterBeefy]

ok, so I may need to unhook the TCM or? Ill admit that I'm not a certified mechanic, (been learning as I go) so the "umbilical" to the transmission is confusing me a little. and how would I go about programing a TCM? or at least checking to see if mine is yet? because even if it is brand new that doesn't mean that its already programmed. is there a way to check the Port for the OBD ii to see if its faulty besides the fuses?

 

[MasterBeefy]

also is there a way to get a wiring diagram for the OBDii that I can at least understand little lmao Most I have found online I cant understand . and I figure the diagram would help with tracing back wires to make sure they are good

 

[VStar650CL]

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.

 

[VStar650CL]

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.

 

[MasterBeefy]

Would an unprogrammed TCM cause the OBDii port to not work and in turn make it to where a new key can't be programmed to it?

 

[MasterBeefy]

I just put a new TCM in it -_- though it's not programmed. So would this cause the OBD port to crash?

 

[VStar650CL]

I just put a new TCM in it -_- though it's not programmed. So would this cause the OBD port to crash?

No, but a defective one will. Try disconnecting it and see if the rest of the bus wakes up.

 

[MasterBeefy]

Ok. So ive got new solenoids on a new Tcm inside the trans now. umbilical is disconected. how would i test the OBD ii to see if its working if i dont have a sensor to plug into it? i have a multimeter but no sensor. I just dont want to call the Locksmith back out to program my key if he cant do it again. -_-

 

[VStar650CL]

You need a cheap scanner, just see if it can read. If the engine is there then everything else should be too.

 

[MasterBeefy]

ok. so after putting in the new TCM, New Solenoids, New Battery, and replaceing the Trans filter, and fluid. I tried to have a key programmed again, but instead of not finding the port. the port worked. but the BCM cant send the code. Not the New or old Codes. I still need to unplugg the Umbilical for the Trans to see if that is what will help the BCM get its butt in gear but as of right now the BCm not sending the codes is the only thing keeping the Truck from starting. I will keep you guys updated as much as i can. The Locksmith is suppose to be back out in the morning and said that he wanted to call the technical support for the Frontier Transponder keys (or something of that nature). I mentioned the process of unhooking the umbilical for the trans and it potentialy helping fix the issue but he was overly skeptical (which i dont understand because its not like it would have hurt anything anyways) and tried programming the key with little change made since he tried the first time. hopefully unhooking the trans works becuase i cant afford to replace the BCM. I dont have any type of scanner that would help read the OBDii codes. all i have that can test anything even remotely electrical is a 7 function Multi-Meter and a homemade test light lol. so any and all advice given is greatly appreciated.

 

[VStar650CL]

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.

 

[MasterBeefy]

He never showed up today. He was swamped with customers. He's suppose to be back tomorrow I will definitely pass the word along and I'll give him the link to the thread here.

 

[MasterBeefy]

OK. Tried unhooking the Trans and programing the key. but the same error code is popping up. "error retrieving the codes from the BCM. try unhooking the programmer after the BCM reads but before the codes are sent and hooking the programmer back in." ...I I'm still completely lost. we tried unhooking the Trans and hooking it back in. I checked all the fuses again.. both outside and in. -_- made sure the TCM was properly installed and shift sensors were placed correctly. I don't have a code scanner though. I have a friend coming tomorrow with one that can clear codes. ill keep yall posted on which codes are thrown.

 

[VStar650CL]

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.

 

[MasterBeefy]

ok. so how would i put the BCM into Nats mode?

 

[VStar650CL]

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.