2008 Nissan Altima no crank red immoblizer light ECM B2607 B2612 B260F

greasemonkey60

Okay, 2008 Altima, push button ignition, 3.5 Liter, red immobilizer light on steady, and car will not turn over. The error I get is B260F.

So far I have
replace FOB battery
replaced all fuses
check brake switch and steering lock
discharged power system
replaced ECM
check CAN system
replaced battery

My brother was replacing the A/C compressor and wanted to test the fuse, but touched some thing on the ECM and it sparked. So he replaced the ECM, but after the car will not turn over. Where are the FOB codes stored in the car? The fob sends out a 7 number code to the car. My scope can see the car receiving the signal, but will not start due to immobilizer issues. If the FOB code were stored there I will have to reprogram the ECM, but if the code is stored elsewhere that's not the issue. You press the start button and it goes to ON, if you press it again everything goes black, press it again and it goes into locked status. The error I keep getting is CAN communication issue, B260F error, and we arrive at our current point in the story. The car will not turn over, and my next step is to trace the whole harness, which I don't want to do. You got any suggestions?

thecardoc3

That code demonstrates what is wrong when someone has to use a trouble tree for diagnostics. The definition of the code is that the BCM cannot communicate with the PCM. The trouble tree doesn't even have you check to find out if the PCM is even powered up.

Can the PCM communicate to the scan tool under both OBDII diagnostics as well as the factory side of the system? Are there other modules setting codes for a loss of communication with the PCM? (aka, IPC, ABS, SRS)

If so, try to confirm if the PCM is sending out a 5v reference signal to any under hood sensor. If the 5v reference is there, then your next step would involve testing of the data bus for communication at the PCM. If the reference voltage is higher than 5v then you need to test and confirm PCM grounds. If it is low or not there then you need to test and confirm all of the powers to the PCM and if they are OK, then start unplugging every sensor one at a time while monitoring for the 5V reference as well as communication to be restored.

Beyond this point any further testing will rely on what you have found with these checks if this hasn't put you onto a track towards the answer.

BTW you need to be able to retrain the NATS system when you replace a PCM. If you don't have a scan tool that is capable of performing that operation after you get the NATS passcode the you would not get the car started with the new PCM anyway.

thecardoc3

You mentioned two other codes, the B2612 and the B2607. Those two codes are pretty important to this system. The first thing that has to happen to start the car, and even to retrain the NATS if you had to replace the push button start module (if equipped) is the steering has to be unlocked. When doing any diagnostics/repairs with this system a technician has to get the NATS passcode for the car, and then enter it into the scan tool under the NATS function and command the steering column to unlock using the bi-directional controls. Only then can he/she proceed with the rest of the service and diagnostic routine. There are some 1250 dealerships around the country that "should" have a technician skilled enough and trained to work on this system. There are only a few hundred independents with that same training and skill who also have a scan tool that supports the NATS functions. Before trying to guess any further and risk making this even more complicated you really do need the help of someone who has the right tools and training.

mikek2015

Reprogramming ECM can be a trickey job, try to consult with some expert technicians. Or else you can replace the ECU to be on safer side.

thecardoc3

At the time that the original post was written the OP mentioned a number of repairs that were attempted by replacing parts with none of the associated set-up or programming routines being performed. That means they were adding problems to the car and getting further away from the solution. By now I would hope that they had found someone that could help them and have this up and running.