Lexus IS250 IS220d GSE20 ALE20 - BRAKE CONTROL
INSPECT SKID CONTROL ECU (STP1 TERMINAL)
INSPECT SKID CONTROL ECU (STP2 TERMINAL)
PERFORM ACTIVE TEST BY INTELLIGENT TESTER (STOP LIGHT CONTROL RELAY)
INSPECT STOP LIGHT CONTROL RELAY
INSPECT STOP LIGHT CONTROL RELAY (POWER SOURCE TERMINAL)
INSPECT SKID CONTROL ECU (STPO TERMINAL)
DTC C1380/64 Stop Light Control Relay Malfunction
DESCRIPTION
Upon receiving the hill-start assist control (HAC) operating signal from the skid control ECU, the relay contact turns on and the stop light comes on.
DTC No. | DTC Detection Condition | Trouble Area |
C1380/64 | When either of the following is detected: When the voltage at the IG1 terminal is between 10 to 14 V and the stop light control relay drive output (STPO) is ON, a signal has not been input to the STP terminal for 5 seconds or more. When the voltage at the IG1 terminal is between 10 to 14 V and the stop light control relay drive output (STPO) is OFF, the signal at the STP1 is different from the input signal at the STP2 for 5 seconds or more. |
STOP SW fuse Stop light switch Stop light switch circuit Stop light control relay (A/T) Stop light control relay circuit (A/T) Brake actuator assembly (Skid control ECU) |
WIRING DIAGRAM
INSPECTION PROCEDURE
- NOTICE:
- When replacing the brake actuator assembly, perform zero point calibration .
- HINT:
- When C1249/49 is output together with C1380/64, inspect and repair the trouble areas indicated by C1249/49 first.
1.INSPECT STOP SW FUSE |

Remove the STOP SW fuse from the main body ECU RH.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Condition Specified Condition STOP SW (7.5 A) fuse Always Below 1 Ω
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NG | |
6.INSPECT STOP LIGHT CONTROL RELAY |

Turn the engine switch off.
Remove the stop light control relay.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Condition Specified Condition 3 - 4 Always Below 1 Ω 3 - 5 Always 10 kΩ or higher 3 - 4 When battery positive voltage is applied to terminal 1 and battery negative voltage to terminal 2 10 kΩ or higher 3 - 5 When battery positive voltage is applied to terminal 1 and battery negative voltage to terminal 2 Below 1 Ω
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OK | |
7.INSPECT STOP LIGHT CONTROL RELAY (POWER SOURCE TERMINAL) |

Measure the voltage according to the value(s) in the table below.
- Standard voltage:
Tester Connection Condition Specified Condition Stop light control relay terminal 5 - Body ground Always 8 to 14 V Stop light control relay terminal 2 - Body ground Engine switch on (IG) 8 to 14 V
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OK | |
8.INSPECT SKID CONTROL ECU (STPO TERMINAL) |

Turn the engine switch off.
Install the stop light control relay.
Disconnect the skid control ECU connector.
Turn the engine switch on (IG).
Measure the voltage according to the value(s) in the table below.
- Standard voltage:
Tester Connection Condition Specified Condition A14-16 (STPO) - Body ground Engine switch on (IG) 10 to 14 V
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OK | |
9.RECONFIRM DTC |
Turn the engine switch off.
Reconnect the skid control ECU connector.
Clear the DTC .
Check if the same DTC is recorded .
- Result:
Condition Proceed to DTC (C1380/64) is not output A DTC (C1380/64) is output B
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A | ||
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