Toyota Sienna Service Manual: Engine Control System Malfunction
DTC C1201/51 Engine Control System Malfunction
DESCRIPTION
If trouble occurs the engine control system, the ECM transmits the abnormality to the skid control ECU.
The skid control ECU set this DTC and the skid control ECU prohibits TRAC and
VSC control. 
INSPECTION PROCEDURE
1 CHECK ENGINE CONTROL SYSTEM
(a) Check if the normal system code is recorded for engine control system.
Result 
REPLACE ECM
Open or Short Circuit in ABS Solenoid Relay Circuit
DESCRIPTION
The ABS solenoid relay is built in the brake actuator assembly. This relay
supplies power to each ABS
solenoid. If the initial check is OK, after the ignition switch is turned to t ...
ECM Communication Circuit Malfunction
DTC C1203/53 ECM Communication Circuit Malfunction
DESCRIPTION
The circuit is used to send TRAC and VSC control information from the skid
control ECU to the ECM, and
engine control information fr ...
Other materials:
Removal
HINT:
Use the same procedures for the RH side and LH side.
The procedures listed below are for the LH side.
1. PRECAUTION
CAUTION:
Be sure to read "PRECAUTION" thoroughly before
servicing.
2. DISCONNECT CABLE FROM NEGATIVE BATTERY
TERMINAL
NOTICE:
Wait for 90 se ...
Terminals of ECU
1. CHECK POWER BACK DOOR ECU
Disconnect the P13 and P14 ECU connectors, and
check the voltage or resistance of each terminal of
the wire harness side connectors
If the result is not as specified, there may be a
malfunction on the wire harness side.
Reconnect the ECU connector ...
Fuel tank
Components
REMOVAL
1. DISCHARGE FUEL SYSTEM PRESSURE
(See page FU-1)
2. REMOVE CHARCOAL CANISTER PROTECTOR (See
page FU-30)
3. REMOVE REAR FLOOR NO. 2 CROSSMEMBER BRACE LH
(a) Remove the 2 bolts and the rear floor No. 2
crossmember brace LH.
4. REMOVE FUEL TANK FILLER HOSE COVER ...