2016 Nissan Frontier CAN BUS ISSUES

Hello, I am working on a 2016 Nissan Frontier with the V6 4.0. It has a crank no start and also sometimes will not even crank. All lights on dash come on and battery is good. Using Autel MS906BT and no communication to the ECM but I have communication to other modules such as TCM, ABS, & 4WD but these modules have U-codes for CAN Bus communication circuit. I hooked up oscilliscope and pins 6 and 14 on DLC and I should have a 2.5VDC bias voltage but I have 6.25VDC bias voltage and the waveform looks very corrupt. I also checked across pins 6 and 14 for resistance and get anywhere from 10 million to 18 million ohms when I should be getting 60. Is there a central joint connector to help troubleshoot these Nissan's...any help is greatly appreciated.

Thank you,

Brian

I honestly believe it is a short to voltage on the CAN lines, but now that the temperature here in Idaho dropped 30 degrees it is no longer acting up. I did isolate the CAN issue down to the TCM or the pigtail harness which are both located inside the transmission. When the vehicle was acting up if I unplugged the harness to the TCM, the bias voltage of 2.5vdc all came back good. Now that the temperature is lower, it is no longer acting up. I will have to further troubleshoot this issue.

You are correct this TCM does control the control side of the starter relay. I am still not sure where the high bias voltage of 3.5vdc - 7vdc was coming from. I believe it was from the TCM or the pigtail harness possibly shorted, but again now it is good. Maybe a loose connection or a wire chaffing...I also added the wire diagram.

Does it drop back out when the transmission warms up? Running the vehicle should push the internal tranny temp higher than whatever your ambient temp was when the problem was present.

I ran it for several hours and hit several bumps and cannot get the problem to duplicate. I even wiggled wire harness around too. I am wondering if the problem is in the pigtail harness inside the transmission itself...

Sounds good. I will take a look at that. Thank you. When you said you had a leak what was actually happening?

Also, when doing the ohm test at the dlc, you want to disconnect the battery negative terminal on Nissan/In Infiniti. You get wacky readings if you don't.

Nissan Technician

I need to check for the coolant leaking issue too, just in case. Thank you.