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:
External temperature
General information
If the indicator drops to +37 ℉/+3 ℃ or lower, a
signal sounds.
A Check Control message is displayed.
There is an increased risk of ice on roads.
Safety information
Warning
Even at temperatures above +37 ℉/+3 ℃
there can be a risk of icy roads, for instance on
bridges ...
Warning lights and
indicators
The warning lights and indicators on the instrument cluster and
center panel inform the driver of the status of the vehicle’s various
systems.
For the purpose of explanation, the following illustration displays
all warning lights and indicators illuminated.
Vehicles with monochrome displ ...
Throttle Actuator Control Motor Circuit
DTC P2102 Throttle Actuator Control Motor Circuit Low
DTC P2103 Throttle Actuator Control Motor Circuit High
DESCRIPTION
The throttle actuator is operated by the ECM and opens and closes the
throttle valve using gears.
The opening angle of the throttle valve is detected by the Throttle Posit ...
