4wd Conversion - Complete Drive Train on Hand

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SimulatedZero
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4wd Conversion - Complete Drive Train on Hand

Postby SimulatedZero » Thu Jun 27, 2019 7:07 am

I have a very specific question and I'm hoping smj999smj is still around. Long story short, I need know the complications of plugging a 4wd Transfer Control Unit into the CAN BUS system on a 2wd 4.0 auto.

I have all the parts and equipment to do a 4wd conversion and I have a solution to mechanically engage 4wd and operate with no issues. I would be building an arduino box to facilitate TC selector motor control. All fine and and good to go.

What I want to try, is a more seamless OEM install. I have the Transfer Control Unit, Transfer Switch, relays, etc... my understanding of the CAN bus system is it's more of a read all signals and act off of input more than a individual programmed response. Doubly considering the transfer control unit is more of a read only unit from existing information. It pulls rotation speed and ATP from the transmission, and pulls wheel speed and ABS from the ABS system.

The only thing I'm not sure of is whether it outputs to effect ABLS. I don't think so... but I'm having a hard time pinning everything down. But, if it's all read only from existing data, I should be able to plug and play into an existing CAN system and have an OEM 4wd control. I can build my own display for engagement no issue. All 4wd diagnostics are onboard self diagnostics in the transfer control unit if I understand it correctly.

Thoughts on Transfer Control Unit interface into 2wd system?


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smj999smj
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Postby smj999smj » Thu Jun 27, 2019 6:30 pm

I've never tried it nor anything like that and I don't know anybody who has, so I really can't give you an answer as to whether it will work, work with issues or not work at all. My thinking is that in order to pull it off, you would need to replace the main electrical harness and related sub-harnesses and IPDM, the instrument cluster and reprogram the ECM software...at the very least. I can't see what you are describing as working without problems given the CAN system.

CAN communication works through a pair of twisted wires that connect all of the control units of the vehicle together. It allows them to effectively have constant communication with each other. Each one doesn't just communicate with the ECM, they communicate with all of the controllers, hence, the are "networking." Without getting into changing the algorithms of the control units, I would have to think, at the very least, it would trigger Can communication trouble codes 1000 or 1001.

There are probably people more familiar with the system than me, so don't let my opinion be the "end all" of what you are attempting to do. I'm just not sure who to recommend that you could ask. I know JWT has done a lot with Nissan ECM's over the years, so maybe they can help? Or, perhaps, the folks at UpRev?

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SimulatedZero
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Postby SimulatedZero » Fri Jun 28, 2019 6:01 am

I guess I'll be the Guinea pig here then. I pulled the FSM for the IPDM and found no mention of the transfer relays, unless I missed it. I have to track their circuit down and run from there. I checked the diagnostics for the consult input /output signals from the transfer control unit and it's all input to the unit. It doesn't output any critical info to the CAN system besides DTC and priority codes. I think that maybe, just maybe, Nissan designed the 4wd system as a standalone system. All other aspects of traction control, VDC, body control are run through the steering, body control, and ABS systems.

I might reach out to UpRev, but I have a feeling I'm going to be doing primary work and research for this project.

Thanks for chiming in

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smj999smj
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Postby smj999smj » Fri Jun 28, 2019 7:41 pm

A transfer relay was used on the AUTO mode transfer case to control the electric oil pump on the transfer case, but I'm not sure if the "standard" transfer case had transfer relay, as well, which would have been for a totally thing than on the AUTO mode unit.


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