DTC C1784: Steering Angle Sensor Communication Error: Procedure

1. Clear the DTC. Refer to DTC CHECK / CLEAR .
2. Perform a road test.
3. Check if DTC C1784 and U0126 are output. Refer to DTC CHECK / CLEAR .
   RESULT
   
   

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

B → See step   5 

A: Go to next step 

1. Check if DTC C1231/31 is output. Refer to DTC CHECK / CLEAR .
   RESULT
   
   

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

B → See step   6 

A: Go to next step 

1. Disconnect the L21 sensor connector.
   Fig 1: Identifying Steering Angle Sensor Connector L21

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage and resistance according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   L21-1 (IG) - Body ground	Power switch ON (IG)	11 to 14 V

   Standard resistance

   Tester Connection	Condition	Specified Condition
   L21-2 (ESS) - Body ground	Always	Below 1 Ω

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

   OK

   No deformation or corrosion.

   HINT: 

   If the steering angle sensor's connector is defective, replace the sensor.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Turn the power switch OFF.
2. Connect the Techstream to the DLC3.
3. Turn the power switch ON (IG) and the Techstream ON.
4. Enter the following menus: Chassis / Air suspension / Data List.
5. Check the values by referring to the table below.
   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.

NG → See step   7 

OK → See step   8