DTC C1784: Steering Angle Sensor Communication Error [08/2015 - 08/2019]: Procedure

1. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).
2. Perform a road test.
3. Check if DTCs C1784 and U0126 are output (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).
   RESULT
   
   

   Condition	Proceed to
   DTC is not output or only DTC C1784 is output	A
   DTCs C1784 and U0126 are output	B

Result: 

B 

GO TO DTC U0126 

(Refer to DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0122: Lost Communication With Vehicle Dynamics Control Module; DTC U0124: Lost Communication with Lateral Acceleration Sensor Module; DTC U0126: Lost Communication with Steering Angle Sensor Module; DTC U0140: Lost Communication with Body Control Module [08/2015 - ] )

Result: 

A 

See step  2

1. Check for steering angle sensor malfunction DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2017] , or refer to DTC CHECK / CLEAR [08/2017 - 08/2019] ).
   RESULT
   
   

   Condition	Proceed to
   DTC is not output	A
   DTC is output	B

Result: 

B 

GO TO VEHICLE STABILITY CONTROL SYSTEM (DIAGNOSTIC TROUBLE CODE CHART) 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [08/2015 - 08/2017] , or refer to DIAGNOSTIC TROUBLE CODE CHART [08/2017 - 08/2018] , or refer to DIAGNOSTIC TROUBLE CODE CHART [08/2018 - 08/2019] )

Result: 

A 

See step  3

1. Disconnect the H6 steering angle sensor connector.
2. Measure the voltage and resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   H6-1 (IG) - Body ground	Ignition switch ON	11 to 14 V
   H6-3 (BAT) - Body ground	Always	11 to 14 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   H6-2 (ESS) - Body ground	Always	Below 1 Ω

3. Check that the steering angle sensor connector is not deformed or corroded.

   OK

   No deformation or corrosion.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Turn the ignition switch off.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to ON.
4. Turn the Techstream on.
5. Enter the following menus: Chassis / Air suspension / Data List.
   AIR SUSPENSION
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Steering Angle	Steering angle sensor reading / Min.: -49152.0 deg Max.: 49150.5 deg	Actual steering angle Left turn: reading increases Right turn: reading decreases	-

   OK

   Steering wheel turning angle value changes when steering wheel is turned.

Result: 

OK 

REPLACE SUSPENSION CONTROL ECU 

(Refer to REMOVAL [08/2015 - ] )

Result: 

NG 

REPLACE STEERING ANGLE SENSOR 

(Refer to REMOVAL [08/2015 - ] )