DTC C1203: ECM Communication Circuit [09/2018 - ]: Procedure

1. Perform initialization and calibration of the linear solenoid valve.

   Refer to INITIALIZATION [03/2017 - ]

   Chassis > ABS/VSC/TRAC > Utility 

   Tester Display
   ECB Utility

   ECB: Electronically Controlled Brake System

   HINT: 

   Before performing initialization and calibration of the linear solenoid valve, DTC C1203 will be output.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  2

1. Turn the engine switch off.
2. Clear the DTCs.

   Chassis > ABS/VSC/TRAC > Clear DTCs 

3. Turn the engine switch off.
4. Turn the engine switch on (IG).
5. Check if the same DTC is output.

   Refer to DTC CHECK / CLEAR [09/2018 - ]

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1203 is output. (w/ variable gear ratio steering system)	A
   DTC C1203 is output. (w/o variable gear ratio steering system)	B
   DTC C1203 is not output.	C

Result: 

B 

See step  5

Result: 

C 

END 

Result: 

A 

See step  3

1. For vehicles with the variable gear ratio steering system, check that the part number of the installed VGRS ECU (front steering control ECU) is correct. For vehicles without the variable gear ratio steering system, make sure that a VGRS ECU (front steering control ECU) is not installed.

   OK

   The presence or absence of the VGRS ECU (front steering control ECU) appropriately matches the specifications of the vehicle.

2. Check if the VGRS ECU (front steering control ECU) had been replaced before the DTC was stored.

   OK

   ECU had not been replaced.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE VGRS ECU (FRONT STEERING CONTROL ECU). Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

OK 

See step  4

1. For vehicles with the variable gear ratio steering system, check that the part number of the installed DRS ECU (rear steering control ECU) is correct. For vehicles without the variable gear ratio steering system, make sure that a DRS ECU (rear steering control ECU) is not installed.

   OK

   The presence or absence of the DRS ECU (rear steering control ECU) appropriately matches the specifications of the vehicle.

2. Check if the DRS ECU (rear steering control ECU) had been replaced before the DTC was stored.

   OK

   ECU had not been replaced.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  5

Result: 

NG 

REPLACE DRS ECU (REAR STEERING CONTROL ECU). Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

1. Check that the proper skid control ECU assembly is installed.

   OK

   Proper skid control ECU assembly is installed.

2. Check if the skid control ECU assembly was replaced before the DTC was recorded.

   OK

   The skid control ECU assembly was not replaced.

   Result

   Result	Proceed to
   OK	A
   NG (A proper skid control ECU assembly is not installed.)	B
   NG (The skid control ECU assembly was replaced.)	C

Result: 

B 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

C 

See step  7

Result: 

A 

See step  6

1. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [09/2018 - ]

   Chassis > ABS/VSC/TRAC > Clear DTCs 

2. Turn the engine switch off.
3. Turn the engine switch on (IG).
4. Check if the same DTC is output.

   Refer to DTC CHECK / CLEAR [09/2018 - ]

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1203 is not output.	A
   DTC C1203 is output.	B

Result: 

A 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2020 - 05/2023]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2023 - ] 

Result: 

B 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

1. After replacing the skid control ECU assembly, check that the initialization and calibration of the linear solenoid valve is being performed.

   OK

   Initialization and calibration of the linear solenoid valve is being performed.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

PERFORM INITIALIZATION AND CALIBRATION OF LINEAR SOLENOID VALVE. Refer to  INITIALIZATION [03/2017 - ] 

Result: 

OK 

See step  8

1. After replacing the skid control ECU assembly, check that the zero point calibration of the yaw rate sensor is being performed.

   OK

   Zero point calibration of the yaw rate sensor is being performed.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

NG 

PERFORM ZERO POINT CALIBRATION OF YAW RATE SENSOR. Refer to  CALIBRATION [03/2017 - 05/2023]  , or refer to  CALIBRATION [05/2023 - ]