Toyota Sienna Service Manual: 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 functioning properly. These are diagnosed by internal "mirroring" of the main and sub CPUs to detect the processors error. If outputs from the processors deviate from the standards, the ECM will illuminate the MIL and set a DTC immediately.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
INSPECTION PROCEDURE
1 INSPECT FOR EXHAUST GAS LEAK
(a) Allow the engine to idle.
(b) Check for exhaust gas leak around the heated oxygen sensor.
OK: No leak from the heated oxygen sensor.
2 CHECK HEATED OXYGEN SENSOR
(a) Connect the intelligent tester to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine at an engine speed of 2500rpm for approximately 90 seconds.
(d) Enter the following menus: DIAGNOSIS / ENHANCED II / ACTIVE TEST / A/F CONTROL.
(e) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
(f) Monitor the voltage outputs of the HO2 sensors (O2S B1S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases in the fuel injection volume.
Standard voltage 
Result 
3 CHECK WHETHER DTC OUTPUT RECURS (IN ADDITION TO DTC P0606)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Clear the DTC.
(e) Turn the ignition switch off.
(f) Disconnect the battery negative terminal and wait for 1 minute.
(g) Connect the battery negative terminal.
(h) Start the engine.
(i) Perform the drive pattern.
(1) Warm up the engine.
(2) Accelerate the vehicle to 50 mph (80 km/h) and stop the vehicle.
(3) Drive the vehicle at 35 to 50 mph (60 to 80 km/h) for 5 minutes or more.
(j) Enter the following menus: DIAGNOSIS / ENHANCED II / DTC INFO / CURRENT CODES.
(k) Read the DTCs.
Result 
REPLACE ECM (See page ES-498)
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
...
Control Module Performance
DESCRIPTION
The ECM continuously monitors its main and sub CPUs. This self-check ensures
that the ECM is
functioning properly. If outputs from the CPUs are different and deviate from
the sta ...
Other materials:
Brake System Malfunction
DTC P1578 Brake System Malfunction
DESCRIPTION
This DTC is output when the VSC system has a problem. Check the VSC system
when this DTC is
output
DTC No.
DTC Detection Condition
Trouble Area
P1578
The ECM receives a brake system error signal for 0.2
...
On-vehicle inspection
1. INSPECT BACK WINDOW (DEFOGGER WIRE)
NOTICE:
When cleaning the glass, wipe the glass along the
wire using a soft and dry cloth. Take care not to
damage the wires.
Do not use detergents or glass cleaners including
abrasive ingredients.
When measuring voltage, wr ...
Removal and installation of fuel control parts
(a) PLACE FOR REMOVING AND INSTALLING FUEL
SYSTEM PARTS
(1) Work in a location with good air ventilation that
does not have welders, grinders, drills, electric
motors, stoves, or any other ignition sources.
(2) Never work in a pit or near a pit as vaporized
fuel will collect in those places. ...
