DTC C1551: IG Power Supply Voltage [12/2019 - 11/2023]: Procedure

1. Disconnect the C67 rack and pinion power steering gear assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Front view of wire harness connector (to Rack and Pinion Power Steering Gear Assembly)

   -

   -

2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   C67-4 (IG) - Body ground	Ignition switch ON	Below 18.5 V

   Result

   Result	Proceed to
   OK	A
   NG (w/o Stop and Start System)	B
   NG (w/ Stop and Start System)	C

Result: 

B 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

C 

GO TO STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT). Refer to  Backup Boost Converter Circuit [12/2019 - 10/2022]  , or refer to  Backup Boost Converter Circuit [10/2022 - 11/2023] 

Result: 

A 

See step  2

1. Clear the DTCs.

   Chassis > EMPS > Clear DTCs 

2. Check for DTCs.

   Chassis > EMPS > Trouble Codes 

   Result

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

Result: 

A 

REPLACE RACK AND PINION POWER STEERING GEAR ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

Result: 

B 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ]