There are a few things: DTC P1668 and P1670 indicates that a communication error has occurred between the PCM and the IDM.
Possible causes:
Open fuse
IDM relay
Open or shorted IDM enable circuit
Open/short in EF circuit
Open/short in FDCS circuit
IDM powering circuits
PCM
I've attached the pinpoint tests for that code that may help. One test does require the breakout box connected to the PCM, which you probably won't have access to. For tests that require the breakout box, but leaving the PCM disconnected, you can simply measure from the required PCM pin(s) (no box really required). The tests do give you an idea of what to look for though. An Electrical and Vacuum Troubleshooting Manual (EVTM) is also very helpful in doing these tests and visualizing what is being looked at in the tests. Cheers!
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