DTC B1A79:13 [ELECTRICAL SUPPLY UNIT (ESU)]


id0902ff061900

Description

Rear fog light circuit malfunction

Detection condition
•  Electrical supply unit (ESU) detects an open circuit in the rear fog light circuit with the ignition switched ON (engine off or on).
Fail-safe
Not applicable
Possible cause
•  DTCs are stored in the PCM.
―  Electrical supply unit (ESU) power supply circuit malfunction
•  Rear fog light bulb malfunction
•  Rear fog light connector or terminal malfunction
•  Electrical supply unit (ESU) connector or terminal malfunction
•  Open circuit in wiring harness between rear fog light terminal A and electrical supply unit (ESU) terminal 2C
•  Electrical supply unit (ESU) malfunction

Diagnostic Procedure

Step

Inspection

Action

1
VERIFY OTHER ELECTRICAL SUPPLY UNIT (ESU) DTCs
•  Retrieve the electrical supply unit (ESU) DTCs using the M-MDS.
•  Is DTC U3006:16 displayed?
Yes
Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
No
Go to the next step.
2
VISUALLY INSPECT REAR FOG LIGHT BULB
•  Visually inspect the rear fog light bulb.
•  Is the rear fog light bulb normal?
Yes
Go to the next step.
No
Replace the rear fog light bulb, then go to Step 7.
3
INSPECT REAR FOG LIGHT CONNECTOR CONDITION
•  Switch the ignition off.
•  Disconnect the negative battery cable.
•  Disconnect the rear fog light 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 7.
4
INSPECT REAR FOG LIGHT GROUND CIRCUIT FOR OPEN CIRCUIT
•  Verify that the rear fog light connector is disconnected.
•  Inspect the wiring harness for continuity between rear fog light terminal B (wiring harness-side) and body ground.
•  Is there continuity?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between rear fog light terminal B and body ground.
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 an open circuit.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has an open circuit.
Go to Step 7.
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 7.
6
INSPECT REAR FOG LIGHT CIRCUIT FOR OPEN CIRCUIT
•  Verify that the rear fog light and electrical supply unit (ESU) connectors are disconnected.
•  Inspect for continuity between rear fog light terminal A (wiring harness-side) and electrical supply unit (ESU) terminal 2C (wiring harness-side).
•  Is there continuity?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between rear fog light terminal A and electrical supply unit (ESU) terminal 2C.
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 an open circuit.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has an open circuit.
Go to the next step.
7
VERIFY THAT REPAIRS HAVE BEEN COMPLETED
•  Always reconnect all disconnected connectors.
•  Connect the negative battery cable.
•  Clear the DTC for the electrical supply unit (ESU) using the M-MDS.
•  Perform the following operation.
―  Operate the light switch to the TNS position.
―  Operate the fog light switch to the R.FOG position.
•  Retrieve the electrical supply unit (ESU) DTCs using the M-MDS.
•  Is the same DTC displayed?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the electrical supply unit (ESU).
Go to the next step.
No
Go to the next step.
8
VERIFY IF OTHER DTCs DISPLAYED
•  Are any other DTCs displayed?
Yes
Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
No
DTC troubleshooting completed.