Monitor Description
WARNING: This page is about a different car, the 2004 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
The HV control ECU performs diagnostic monitoring to verify proper operation of internal and external ECU systems. In one of these diagnostics, the HV control ECU monitors the important RAM circuits of the HV control ECU.
If the HV control ECU detects an error in the important RAM circuits, it will conclude that there is an internal malfunction in the HV control ECU. The HV control ECU will illuminate the MIL and set a DTC.