DTC P0604: Internal Control Module Random Access Memory (RAM) Error [08/2015 - ]: Description

The ECM continuously monitors its own internal memory status, internal circuits, and output signals transmitted to the throttle actuator. This self-check ensures that the ECM is functioning properly. If any malfunction is detected, the ECM stores the appropriate DTC and illuminates the MIL.

The ECM memory status is diagnosed by internal mirroring of the main CPU and sub CPU to detect Random Access Memory (RAM) errors. The two CPUs also perform continuous mutual monitoring. The ECM illuminates the MIL and stores a DTC if: 1) outputs from the 2 CPUs are different or deviate from the standard, 2) the signals sent to the throttle actuator deviate from the standard, 3) a malfunction is found in the throttle actuator supply voltage, or 4) any other ECM malfunction is found.