DTC C1A4B: Stop Light Relay Circuit [07/2015 - ]: Procedure

1. Turn the engine switch off.
2. Check the engine room junction block assembly (Refer to PROCEDURE - Step 1 ).

   OK

   The engine room junction block assembly is normal.

Result:  NG

NG 

INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (RESULT OF SIGNAL READING CHECK) 

(Refer to PROCEDURE - Step 2 )

Result:  OK

OK 

See step  2

1. Turn the engine switch off.
2. Disconnect the A40 brake actuator assembly (skid control ECU) connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Brake Actuator Assembly (Skid Control ECU))

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A40-26 (STPO) - Body ground	Always	11 to 14 V

Result:  NG

NG 

See step  6

Result:  OK

OK 

See step  3

1. Select the Active Test on the Techstream (Refer to DATA LIST / ACTIVE TEST [07/2015 - ] ).
   ABS/VSC/TRAC
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Stop Light Relay	Switches stop light on/off	ON/OFF	Test possible at vehicle speed of 0 km/h (0 mph)

2. Perform the Active Test of the engine room junction block assembly (stop light relay) using the Techstream.
3. Select the Data List on the Techstream (Refer to DATA LIST / ACTIVE TEST [07/2015 - ] ).
   ABS/VSC/TRAC
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stop Light Relay Output	STPO terminal output condition/ ON or OFF	ON: Output OFF: Not output	-

4. Check for engine room junction block assembly (stop light relay) operation using the Data List and stop light operation by performing an Active Test.

   Result

   Result	Proceed to
   Data List content and stop light operation are abnormal.	A
   Data List content is normal but stop lights do not turn on or off.	B

Result:  B

B 

See step  5

Result:  A

A 

See step  4

1. Select the Active Test on the Techstream (Refer to DATA LIST / ACTIVE TEST [07/2015 - ] ).
   ABS/VSC/TRAC
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Stop Light Relay	Switches stop light on/off	ON/OFF	Test 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 engine room junction block assembly connector.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   1G-3 (ACC) - Body ground	Engine switch on (IG) (Active test is OFF)	11 to 14 V
   1G-3 (ACC) - Body ground	Engine switch on (IG) (Active test is ON)	Below 1.5 V

Result:  OK

OK 

REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (STOP LIGHT RELAY) 

(Refer to COMPONENTS [07/2015 - ] )

Result:  NG

NG 

REPLACE BRAKE ACTUATOR ASSEMBLY 

(Refer to COMPONENTS [07/2015 - ] )

1. Turn the engine switch off.
2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly
3. Disconnect the A40 brake actuator assembly (skid control ECU) connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1F-11 (STOP) - A40-5 (STP2)	Always	Below 1 Ω

Result:  OK

OK 

REPLACE BRAKE ACTUATOR ASSEMBLY 

(Refer to COMPONENTS [07/2015 - ] )

Result:  NG

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. Turn the engine switch off.
2. Remove the engine room junction block assembly from the engine room relay block and junction block assembly
3. Disconnect the A40 brake actuator assembly (skid control ECU) connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1G-3 (ACC) - A40-26 (STPO)	Always	Below 1 Ω
   1G-3 (ACC) or A40-26 (STPO) - Body ground	Always	10 kΩ or higher

Result:  OK

OK 

REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (STOP LIGHT RELAY) 

(Refer to COMPONENTS [07/2015 - ] )

Result:  NG

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR