DTC C1203: ECM Communication Circuit Malfunction: Procedure

1. Check that the proper ECM and brake actuator assembly (skid control ECU) are installed.

   OK

   Proper ECUs are installed.

   Result

   Result	Proceed to
   OK (for 2AZ-FE)	A
   OK (for 2ZR-FE)	B
   NG	C

C → REPLACE ECUS WITH PROPER ONES 

B → See step   3 

A → See step   2