Monitor Description
WARNING: This page is about a different car, the 2019 Toyota Highlander, 2018 Toyota Highlander, and 2017 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
The hybrid vehicle control ECU assembly performs diagnostic tests to verify proper operation of internal and external ECU systems. In one of these tests, the hybrid vehicle control ECU assembly monitors specific RAM circuits of the hybrid vehicle control ECU assembly. If the hybrid vehicle control ECU assembly detects an error in the RAM circuits, it will conclude that there is an internal malfunction and will illuminate the MIL and store a DTC.