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
1. Disconnect cable from negative battery
terminal
2. REMOVE STEERING COLUMN COVER LOWER
(A) insert the key into the ignition key cylinder and
release the steering lock.
(B) turn the steering wheel clockwise to gain access to
the screw and remove the screw.
(c) Turn the steering whe ...
Inspection
1. INSPECT SEAT HEATER SWITCH LH
Measure the resistance of the seat heater switch
when the switch is operated.
Resistance
If the result is not as specified, replace the switch.
HINT:
As the dial is being turned, the resistance changes
gradually.
Push the seat h ...
ABS Warning Light Remains ON
DESCRIPTION
If any of the following is detected, the ABS warning light remains on.
The skid control ECU connectors are disconnected from the skid control
ECU.
There is a malfunction in the skid control ECU internal circuit.
There is an open in the harness between the combination meter an ...
