Toyota Sienna Service Manual: 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
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)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read DTCs.
Result 
REPLACE ECM
System Voltage
MONITOR DESCRIPTION
The battery supplies electricity to the ECM even when the ignition switch is
off. This power allows the
ECM to store data such as DTC history, freeze frame data and fuel tr ...
ECM / PCM Processor
DESCRIPTION
The ECM continuously monitors its internal processors (CPUs), A/F sensor
transistors and heated oxygen
sensor (HO2S) transistors. This self-check ensures that the ECM is functionin ...
Other materials:
Installation
1. INSTALL FRONT PASSENGER AIRBAG ASSEMBLY
Install the front passenger airbag assembly with the
2 screws.
2. INSTALL INSTRUMENT PANEL SUB-ASSEMBLY
3. CONNECT FRONT PASSENGER AIRBAG ASSEMBLY CONNECTOR
Connect the connector to the front passenger airbag
assembly.
...
Slip Indicator Light does not Come ON
DESCRIPTION
The skid control ECU is connected to the combination meter via CAN and
multiplex communications.
The SLIP indicator blinks during VSC and/or TRAC operation.
When the system fails, the SLIP indicator comes on to warn the driver.
WIRING DIAGRAM
Refer to Slip Indicator Light Rema ...
Data list / active test
1. READ DATA LIST
HINT:
Using the intelligent tester's DATA LIST allows switch,
actuator and other item values to be read without
removing any parts. Reading the DATA LIST early in
troubleshooting is one way to save time.
Connect the intelligent tester with CAN VIM to the
DLC3.
&n ...
