DTC C1A4B: Stop Light Relay Circuit [06/2015 - 11/2018]: Procedure

1. Check that the stop lights come on when the brake pedal is depressed and go off when the brake pedal is released.

   OK

   Condition	Illumination Condition
   Brake pedal depressed	On
   Brake pedal released	Off

   Result

   Proceed to
   OK
   NG

Result: 

NG 

GO TO LIGHTING SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2015 - 11/2018] 

Result: 

OK 

See step  2

1. Disconnect the stop light switch assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Stop Light Switch Assembly)

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   A17-6 (B) - Body ground	Power switch on (IG)	11 to 14 V
   A17-7 (B) - Body ground	Power switch off	11 to 14 V

3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A17-2 (GND) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Remove the stop light switch assembly.

   Refer to REMOVAL [06/2015 - ]

2. Inspect the stop light switch assembly.

   Refer to ON-VEHICLE INSPECTION [06/2015 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [06/2015 - ] 

Result: 

OK 

See step  4

1. Disconnect the A17 stop light switch assembly connector.
2. Disconnect the A63 skid control ECU (brake booster with master cylinder assembly) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A17-4 (ACC) - A63-3 (STPO)	Always	Below 1 Ω
   A17-4 (ACC) or A63-3 (STPO) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Turn the power switch off and wait for at least 2 minutes.
2. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [06/2015 - 11/2018]

   Body Electrical > Pre-Collision 2 > Clear DTCs 

3. Make sure that the DTC detection conditions are met.

   HINT: 

   If the detection conditions are not met, the system cannot detect the malfunction.

   • Using the Techstream, perform the Active Test "Stop Light Relay" with the power switch on (IG).
4. Check for DTCs.

   Refer to DTC CHECK / CLEAR [06/2015 - 11/2018]

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1A4B is not output	A
   DTC C1A4B is output	B

Result: 

B 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2015 - 11/2018] 

Result: 

A 

See step  6

1. Replace driving support ECU assembly.

   Refer to REMOVAL [06/2015 - 11/2018]

   NOTE:

   When replacing the driving support ECU assembly, always replace it with a new one. If a driving support ECU assembly which was installed to another vehicle is used, the information stored in the driving support ECU assembly will not match the information from the vehicle. As a result, a DTC may be stored.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  7

1. Turn the power switch off and wait for at least 2 minutes.
2. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [06/2015 - 11/2018]

   Body Electrical > Pre-Collision 2 > Clear DTCs 

3. Make sure that the DTC detection conditions are met.

   HINT: 

   If the detection conditions are not met, the system cannot detect the malfunction.

   • Using the Techstream, perform the Active Test "Stop Light Relay" with the power switch on (IG).
4. Check for DTCs.

   Refer to DTC CHECK / CLEAR [06/2015 - 11/2018]

   Body Electrical > Pre-Collision 2 > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1A4B is not output	A
   DTC C1A4B is output	B

Result: 

A 

REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY). Refer to  REMOVAL [06/2015 - 11/2018] 

Result: 

B 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2015 - 11/2018]