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DTC B124A:11 [ELECTRICAL SUPPLY UNIT (ESU)]

Description	DRL circuit malfunction
Detection condition	Electrical supply unit (ESU) detects a short to ground in the DRL circuit with the ignition switched ON (engine off or on).
Fail-safe	Not applicable
Possible cause	DRL bulb (LH) malfunction (bulb type) DRL bulb (RH) malfunction (bulb type) DRL (LH) connector or terminal malfunction DRL (RH) connector or terminal malfunction Electrical supply unit (ESU) connector or terminal malfunction Short to ground in wiring harness between the following terminals: Electrical supply unit (ESU) terminal 4J—DRL (LH) terminal A Electrical supply unit (ESU) terminal 4J—DRL (RH) terminal A DRL (LH) malfunction (LED type) DRL (RH) malfunction (LED type) Electrical supply unit (ESU) malfunction

Diagnostic Procedure

Step	Inspection		Action
1	VISUALLY INSPECT DRL BULB (LH) NOTE: For vehicles with DRL (LED type), go to Step 3. Visually inspect the DRL bulb (LH). Is the DRL bulb (LH) normal?	Yes	Go to the next step.
		No	Replace the DRL bulb (LH), then go to Step 9. (See DAYTIME RUNNING LIGHT (DRL) BULB REMOVAL/INSTALLATION.)
2	VISUALLY INSPECT DRL BULB (RH) Visually inspect the DRL bulb (RH). Is the DRL bulb (RH) normal?	Yes	Go to the next step.
		No	Replace the DRL bulb (RH), then go to Step 9. (See DAYTIME RUNNING LIGHT (DRL) BULB REMOVAL/INSTALLATION.)
3	INSPECT DRL (LH) CONNECTOR CONDITION Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.) Disconnect the DRL (LH) connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
		No	Repair or replace the connector, then go to Step 9.
4	INSPECT DRL (RH) CONNECTOR CONDITION Disconnect the DRL (RH) connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
		No	Repair or replace the connector, then go to Step 9.
5	INSPECT ELECTRICAL SUPPLY UNIT (ESU) CONNECTOR CONDITION Disconnect the electrical supply unit (ESU) connector. Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. Is the connector normal?	Yes	Go to the next step.
		No	Repair or replace the connector, then go to Step 9.
6	INSPECT DRL CONTROL CIRCUIT FOR SHORT TO GROUND Verify that the DRL (LH)/(RH) and electrical supply unit (ESU) connectors are disconnected. Inspect for continuity between electrical supply unit (ESU) terminal 4J (wiring harness-side) and body ground. Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: Electrical supply unit (ESU) terminal 4J—DRL (LH) terminal A Electrical supply unit (ESU) terminal 4J—DRL (RH) terminal A If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. Go to Step 9.
		No	Bulb type: Go to Step 9. LED type: Go to the next step.
7	VERIFY IF MALFUNCTIONING LOCATION IS DRL (LH) DEPENDING ON REPEATABILITY Always reconnect all disconnected connectors. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.) Clear the DTC for the electrical supply unit (ESU) using the M-MDS. (See CLEARING DTC [ELECTRICAL SUPPLY UNIT (ESU)].) Retrieve the electrical supply unit (ESU) DTCs using the M-MDS. (See DTC INSPECTION [ELECTRICAL SUPPLY UNIT (ESU)].) Is the same DTC displayed?	Yes	Replace the DRL (LH), then go to the next step. (See DAYTIME RUNNING LIGHT (DRL) REMOVAL/INSTALLATION.)
		No	Go to Step 10.
8	VERIFY IF MALFUNCTIONING LOCATION IS DRL (RH) DEPENDING ON REPEATABILITY Clear the DTC for the electrical supply unit (ESU) using the M-MDS. (See CLEARING DTC [ELECTRICAL SUPPLY UNIT (ESU)].) Retrieve the electrical supply unit (ESU) DTCs using the M-MDS. (See DTC INSPECTION [ELECTRICAL SUPPLY UNIT (ESU)].) Is the same DTC displayed?	Yes	Replace the DRL (RH), then go to the next step. (See DAYTIME RUNNING LIGHT (DRL) REMOVAL/INSTALLATION.)
		No	Go to Step 10.
9	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.) Clear the DTC for the electrical supply unit (ESU) using the M-MDS. (See CLEARING DTC [ELECTRICAL SUPPLY UNIT (ESU)].) Retrieve the electrical supply unit (ESU) DTCs using the M-MDS. (See DTC INSPECTION [ELECTRICAL SUPPLY UNIT (ESU)].) Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the electrical supply unit (ESU). (See ELECTRICAL SUPPLY UNIT (ESU) REMOVAL/INSTALLATION.) Go to the next step.
		No	Go to the next step.
10	VERIFY IF OTHER DTCs DISPLAYED Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [ELECTRICAL SUPPLY UNIT (ESU)].)
		No	DTC troubleshooting completed.

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DTC B124A:11 [ELECTRICAL SUPPLY UNIT (ESU)]