C1380

BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C1380: Stop Light Control Relay Malfunction
C1380 - Stop Light Control Relay Malfunction

DESCRIPTION

Upon receiving the hill-start assist control operating signal from the skid control ECU, the relay contact turns on and the stop light comes on.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
* When replacing the master cylinder solenoid, perform calibration Programming and Relearning.
* Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT
When DTC C1425 is output together with DTC C1380, inspect and repair the trouble areas indicated by DTC C1425 first C1425.

PROCEDURE

1. CHECK STOP LIGHT SWITCH OPERATION

(a) Check that the stop light comes on when the brake pedal is depressed and goes off when the brake pedal is released.

OK:

Stop light switch function is normal.

NG -- INSPECT STOP LP RELAY
OK -- Continue to next step.

2. CHECK TERMINAL VOLTAGE (STP)

(a) Disconnect the A6 skid control ECU connector.

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





Standard Voltage:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

3. CHECK TERMINAL VOLTAGE (STP2)

(a) Disconnect the A6 skid control ECU connector.

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





Standard Voltage:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.

ABS/VSC/TRAC





(f) Check the operation of the stop light when operating it with the Techstream.

OK:

The stop light turns on or off in accordance with the Techstream.

NG -- CHECK TERMINAL VOLTAGE (STOP LP RELAY POWER SOURCE TERMINAL)
OK -- Continue to next step.

5. RECONFIRM DTC

(a) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(b) Check if the same DTC is output Reading and Clearing Diagnostic Trouble Codes.

HINT
Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.

Result





B -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

A -- REPLACE MASTER CYLINDER SOLENOID Disassembly

6. CHECK TERMINAL VOLTAGE (STOP LP RELAY POWER SOURCE TERMINAL)

(a) Remove the STOP LP relay from the engine room relay block.

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





Standard Voltage:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

7. INSPECT STOP LP RELAY

(a) Remove the STOP LP relay from the engine room relay block.

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





Standard Resistance:





Text in Illustration





NG -- REPLACE STOP LP RELAY
OK -- Continue to next step.

8. CHECK TERMINAL VOLTAGE (STPO)

(a) Disconnect the A6 skid control ECU connector.

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





Standard Voltage:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

9. RECONFIRM DTC

(a) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(b) Turn the ignition switch off.

(c) Check if the same DTC is output Reading and Clearing Diagnostic Trouble Codes.

Result





B -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

A -- REPLACE MASTER CYLINDER SOLENOID Disassembly

10. INSPECT STOP LP RELAY

(a) Remove the STOP LP relay from the engine room relay block.

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





Standard Resistance:





Text in Illustration





NG -- REPLACE STOP LP RELAY

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)