I really want to know the code P0730D mean.
Which part I should change or fix it ?
thanks so much

 

(P0730) TRANSMISSION CONTROL SYSTEM (MIL REQUEST)
For a complete Electronic Control Module Circuit Diagram, Refer to Page 8E-45.
Diagnostic Test
1. DTC PRESENT IN TRANSMISSION CONTROL MODULE (TCM)
This is an informational DTC letting you know that a DTC(s) is stored in
the Transmission Control Module.
Erase this DTC from the PCM after all Transmission DTC(s) have been
repaired.
Using the DRB IIIT, read the Transmission Controller DTC and refer to the
Transmission Category and perform the appropriate symptom.
PCM Diagnostic Information complete.
Continue
Test Complete.

So the P0730D code looks like an extended code read by the DRB III system from the TCM.On your other thread others posted their fixes for the same code and the part number. You would need to get that/those parts, gasket, transmisson fluid and replace.