Possible Causes
WARNING: This page is about a different car, the 2003 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
If DTC P1600 exists, the ECM will not store any other DTCs. DTC is set when open in back-up power source is detected. Possible causes are:
- Back-up power source circuit is open.
- Defective ECM.