Xterra can bus

[Max wedgehind]

Hi, new to the forum, needing advanced technical support. I have an 06 xterra, parked for several months while sourcing a good used motor. When I was ready to swap I found the battery dead. Put on a charger and the abs pump was running constantly so I unplugged it. No mil light no communication and no start. Pushed it into the shop and completed the engine swap. Still no communication etc. Sent the main ecu to Miami and was told it was bad and not repairable so bought new. Same problem. Replaced ipdm with black one, no change. Unplugged every connector I could find. Learned about can bus testing. Testing 6 and 14 I get 6 ohms and no voltage, something must be shorted. Unplugged even more stuff with no change. Yesterday I unplugged the abs computer again and ohs shot over 400. How many terminal resistors are there? Still no communication anyway. Is my new ecu bad and the abs too?

[VStar650CL]

There are terminator resistors in the IPDM and BCM, it should read just over 50 ohms with both in place or 100 with one unplugged. Try unplugging the transmission umbilical and see if everything wakes up. The TCM's on Xterras, D40 Frontiers, and R51 Pathies are notorious for crashing the whole bus when they die.

[NissanFarm]

The FSM has a comprehensive section on diagnosing CAN communication issues. This site generously has them available.
Hopefully the OP obtained the FSM and went through the procedures to isolate the source of the problem.

I've never heard of much in the way of "good" results by sending automotive control modules to so called module repair shops.
It's usually the same result....sent it in, they said it was bad, sent a replacement ($$$), same problem.

Does anyone know of such a shop where good results are consistent?

From my experience there are only a few components in them that could be replaced if bad and it's just an opinion but more often than not when they really do fail it's likely to be a corruption of the core code in the main processing chip which would require unobtanium resources to replace and reprogram for ones specific vehicle.
Dealerships usually can do this but it's a costly proposition usually. I don't think independent shops have access to these resources.
I also think that more often than not the module was not the problem anyway.

I've opened a few and replaced capacitors and 1206 / 1802 diodes etc and have a very good grasp on testing and repairing circuit boards and electronics and still can't say I've had much success.

[VStar650CL]

From my experience there are only a few components in them that could be replaced if bad and it's just an opinion but more often than not when they really do fail it's likely to be a corruption of the core code in the main processing chip which would require unobtanium resources to replace and reprogram for ones specific vehicle.

Corrupt flash isn't common, although it's more frequent on stuff from the early 2000's when typical guaranteed flash durations were still about 20 years. Most modern flash has 40+ year durations and I can't recall ever seeing a verifiable corruption issue on anything past 2010.

When internal CANbus failures occur it's generally the fault of the CAN interface circuit and not the flash program. We commonly see them blown up by reverse jumpstarts or lighting strikes. That was often fixable on older ECU's because the drivers were discrete chips like the ADM3051, but nowadays most of the mother IC's are ASIC's with CAN built in. That pretty much guarantees they're unfixable, because the ASIC's are always proprietary and good luck getting one.

[Niti QX4]

It's a shame that an otherwise good 20 year old vehicle will be sidelined because of module. I wonder if there is an emulator that could be developed as a possible replacement. Maybe copy the existing code from a good ASIC and load in a PI or something similar

[VStar650CL]

It's a shame that an otherwise good 20 year old vehicle will be sidelined because of module. I wonder if there is an emulator that could be developed as a possible replacement. Maybe copy the existing code from a good ASIC and load in a PI or something similar

Doable, but except for simple-minded "one task" stuff like power window controllers, I think you'd be into a crapload of reverse engineering. Our favorite old OG Murano recently went to JY heaven because we couldn't get electronic parts to fix it anymore. Over 500K miles, the owner was heartbroken. I'd imagine at some point folks with deep pockets will start doing exactly what you're talking about to keep valuable antiques on the road, but for the average owner, it's cry and play taps. Modern cars are what they are, and your great grandpa frankly wouldn't recognize them.