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

1. Depress the brake pedal, push the power switch and check that the power switch turns on (READY).

   OK

   The power switch turns on (READY).

Result: 

NG 

REFER TO HYBRID CONTROL SYSTEM 

Refer to PROBLEM SYMPTOMS TABLE [11/2015 - 06/2017] Refer to PROBLEM SYMPTOMS TABLE [06/2017 - ] )

Result: 

OK 

See step  2

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

   OK

   The stop lights illuminate when the brake pedal is depressed. The stop lights turn off when the brake pedal is released.

Result: 

NG 

REFER TO LIGHTING SYSTEM 

Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2015 - ] )

Result: 

OK 

See step  3

1. Inspect the stop light switch assembly (Refer to ON-VEHICLE INSPECTION [11/2015 - 06/2017]

   OK

   The stop light switch assembly is normal.

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY 

Refer to COMPONENTS [11/2015 - ] )

Result: 

OK 

See step  4

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
5. Check for DTCs (Refer to DTC CHECK / CLEAR [11/2015 - ] ).
   RESULT
   
   

   Result	Proceed to
   Electronically controlled brake system DTCs are not output	A
   Electronically controlled brake system DTCs are output	B

Result: 

B 

REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) 

Refer to COMPONENTS [11/2015 - ] )

Result: 

A 

See step  5

1. Turn the power switch off.
2. Disconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Skid control ECU (Brake booster with master cylinder assembly))

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A41-3 (STPO) - Body ground	Always	11 to 14 V

4. Connect the A41 skid control ECU (brake booster with master cylinder assembly) connector.

Result: 

NG 

See step  9

Result: 

OK 

See step  6

1. According to the display on the Techstream, perform the Active Test Stop Light Relay (Refer to DATA LIST / ACTIVE TEST [11/2015 - 06/2017] ).
   CHASSIS > ABS/VSC/TRAC > ACTIVE TEST
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Stop Light Relay	Stop light control relay (stop light switch assembly)	ON/OFF	Possible at vehicle speed of 0 km/h (0 mph)

2. According to the display on the Techstream, read the Data List item Stop Light Relay Output (Refer to DATA LIST / ACTIVE TEST [11/2015 - 06/2017]
   CHASSIS > ABS/VSC/TRAC > DATA LIST
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stop Light Relay Output	Stop light control relay (stop light switch assembly) output / ON or OFF	ON: Relay output on OFF: Relay output off	-

3. Check that the Data List item Stop Light Relay Output changes between ON and OFF and the stop lights turn on and off according to the operation of the Active Test.
   RESULT
   
   

   Result	Proceed to
   The Data List item Stop Light Relay Output does not change between ON and OFF and the stop lights do not turn ON and OFF according to the operation of the Active Test.	A
   The Data List item Stop Light Relay Output changes between ON and OFF but the stop lights do not turn ON and OFF according to the operation of the Active Test.	B

Result: 

NG 

See step  8

Result: 

OK 

See step  7

1. According to the display on the Techstream, perform the Active Test Stop Light Relay (Refer to DATA LIST / ACTIVE TEST [11/2015 - 06/2017] ).
   CHASSIS > ABS/VSC/TRAC > ACTIVE TEST
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Stop Light Relay	Stop light control relay (stop light switch assembly)	ON/OFF	Possible at vehicle speed of 0 km/h (0 mph)

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

   HINT: 

   Do not disconnect the stop light switch assembly connector.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A73-4 (ACC) - Body ground	Power switch on (IG) (Active test OFF)	11 to 14 V
   	Power switch on (IG) (Active test ON)	Below 1.5 V

Result: 

OK 

REPLACE STOP LIGHT SWITCH ASSEMBLY 

Refer to COMPONENTS [11/2015 - ] )

Result: 

NG 

REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) 

Refer to COMPONENTS [11/2015 - ] )

1. Turn the power switch off.
2. Disconnect the A73 stop light switch assembly connector.
3. Disconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A73-1 (OUT) - A41-33 (STP)	Always	Below 1 Ω

5. Connect the A41 skid control ECU (brake booster with master cylinder assembly) connector.
6. Connect the A73 stop light switch assembly connector.

Result: 

OK 

REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) 

Refer to COMPONENTS [11/2015 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) 

1. Turn the power switch off.
2. Disconnect the A73 stop light switch assembly connector.
3. Disconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A73-4 (ACC) - A41-3 (STPO)	Always	Below 1 Ω
   A73-4 (ACC) or A41-3 (STPO) - Body ground	Always	10 kΩ or higher

5. Connect the A41 skid control ECU (brake booster with master cylinder assembly) connector.
6. Connect the A73 stop light switch assembly connector.

Result: 

OK 

REPLACE STOP LIGHT SWITCH ASSEMBLY 

Refer to COMPONENTS [11/2015 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)