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:
Disassembly
1. REMOVE OCCUPANT CLASSIFICATION ECU
2. REMOVE FRONT SEAT CUSHION SHIELD INNER RH
Remove the screw.
Using a screwdriver, disengage the claws and
remove the cushion shield inner.
HINT:
Tape the screwdriver tip before use.
3. REMOVE FRONT SEAT INNER BELT ASSEMBLY RH
&nbs ...
Disassembly
1. REMOVE BRAKE MASTER LESS RESERVOIR TANK CYLINDER SUB-ASSEMBLY
(a) Using soft jaws on the vise, hold the brake master
cylinder in a vise through aluminum plates.
(b) Using a screwdriver, remove the O-ring.
(c) Using SST, remove the brake tube from the brake
master cylinder.
SST 09023 ...
Problem symptoms table
HINT:
Use the table below to help determine the cause of the
problem symptom. The likely causes of the problem are
indicated in descending order. Check each suspected area
in order. Repair or replace faulty parts or perform
adjustments as necessary.
Inspect the fuse and rel ...
