DTC P0604 Internal Control Module Random Access Memory (RAM) Error
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 sets the appropriate DTC and illuminates the MIL.
The ECM memory status is diagnosed by internal mirroring of the main CPU and the sub CPU to detect Random Access Memory (RAM) errors. The two CPUs also perform continuous mutual monitoring. The ECM illuminates the MIL and sets a DTC if: 1) outputs from the two CPUs are different or deviate from the standards, 2) the signals sent to the throttle actuator deviate from the standards, 3) a malfunction is found in the throttle actuator supply voltage, and 4) any other ECM malfunction is found.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
ECM RAM errors:
INSPECTION PROCEDURE
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0604)
Result
REPLACE ECM
Installation
1. INSTALL FRONT DOOR WINDOW FRAME MOULDING
Remove the tape from the front door window frame
moulding.
Clean the contact surface of the vehicle body with
white gasoline.
Clean the outer circumference of the front door
window frame moulding with white gasoline.
Apply new double-si ...
Diagnosis system
1. CHECK BATTERY VOLTAGE
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge the battery before
proceeding.
2. CHECK DLC3
(a) The ECU uses the ISO 15765-4 for communication
protocol. The terminal arrangement of the DLC3
complies with SAE J1962 and matches the ISO
15765-4 f ...
Correct use of the seat belts
Make sure that all occupants are wearing their seat belts before driving
the vehicle. Use a child restraint system appropriate for the child until the child
becomes large enough to properly wear the vehicle’s seat belt.
Adjusting the mirrors
Make sure that you can see backward clearly by adjus ...