Auto transmission RB25 swap

[skillzilla]

I have a friend contemplating an RB25/S14 swap and retaining the auto transmission (in all fairness it is going to be for his wife, but I have no problems with auto trans personally ). ANNNYYWAAAYYYSSS, mainly Im wondering how the transmission and ecu will react without the transmission control unit (secondary ECU that controls the transmission only), and if it is an absolute MUST, where can one source a unit?

If I had to venture a guess Id say it is most definitiley a must unless you want a one-speed, but Ive never done an auto swap and didnt come across anything while searching so I guess it is up in the air at this point. Basically Im thinking, aside from the normal stuff, he will need:

TCUTCU HarnessPerhaps an Auto Skyline fuse/relay block?Skyline shift lock wiring?

So if you have any ideas lemme know, its just planning at this point (not like we are waist deep in the swap and dont know what the hell to do next, like I see on here often ) so feel free to criticize, flame, call names, DIAF, GTFO, etc. Just gimme some thoughts.

[Carl H]

wont need much man, just the engine and trans...the real trick is in the wiring, just use the ka tcu to run the trans, it will be fine.

[skillzilla]

Sweet, so keep the KA lower haness and sensors of course, keep the TCU harness intact, and just run the signal to the RB ECU? Sounds easy enough.

[Sykoperformance]

Not quite that simple. Unfortuately the harness leading to the auto trans is hard wired straight to the valvebody. This means the wires must be cut and spliced. If you get lucky, the connectors from the RB25 trans may be the same as on the KA. Even then, you can't just plug them in without tracing all the wires and probably switching some pins around.

The main circuits you will be dealing with are the two shift solenoids, pressure control solenoid, and Manual lever position sensor. There might be some pressure sensors as well to give feedback to the TCU. We've never done this wiring conversion, so I'd have to look at the schematics to know for sure.

All I can say is you better have a decent understanding of automotive electrical systems and automatic transmission systems before attempting to do this yourself. Otherwise, you will probably wind up with a 1 speed or 0 speed burn't transmission.

[skillzilla]

Thanks for the info, I will definitely pass it on. The good news is I wont be doing any wiring on it, so if he is out an RB25 transmission its not on my account Still, Ill make double sure he understands it may take some head scratching and wire tracing.