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2014 - Mazda6 - Body and Accessories

DTC U0231:68 [FRONT BODY CONTROL MODULE (FBCM)]



Description

Communication error with auto light sensor/rain sensor

Detection condition

  • Front body control module (FBCM) could not receive the signals from the auto light sensor/rain sensor for 5 s or more with the ignition switched ON (engine off or on).

Fail-safe function

Not applicable

Possible cause

  • Auto light sensor/rain sensor connector or terminal malfunction

  • Front body control module (FBCM) connector or terminal malfunction

  • Short to ground in wiring harness between auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G

  • Short to power supply in wiring harness between auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G

  • Open circuit in wiring harness between auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G

  • Auto light sensor/rain sensor malfunction

  • Front body control module (FBCM) malfunction


Diagnostic Procedure

Step

Inspection

Action

1

VERIFY FRONT BODY CONTROL MODULE (FBCM) DTCs AGAIN

Yes

Go to the next step.

No

Go to Step 9.

2

INSPECT AUTO LIGHT SENSOR/RAIN SENSOR CONNECTOR
  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].)

  • Disconnect the auto light sensor/rain sensor 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 8.

3

INSPECT FRONT BODY CONTROL MODULE (FBCM) CONNECTOR
  • Disconnect the front body control module (FBCM) 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 8.

4

INSPECT FOR SHORT TO GROUND IN AUTO LIGHT SENSOR/RAIN SENSOR CIRCUIT
  • Verify that the auto light sensor/rain sensor and front body control module (FBCM) connectors are disconnected.

  • Inspect for continuity between front body control module (FBCM) terminal 2G (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 auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G.

    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 8.

No

Go to the next step.

5

INSPECT FOR SHORT TO POWER SUPPLY IN AUTO LIGHT SENSOR/RAIN SENSOR CIRCUIT
  • Verify that the auto light sensor/rain sensor and front body control module (FBCM) connectors are disconnected.

  • Reconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].)

  • Switch the ignition ON (engine off or on).

  • Measure the voltage at the front body control module (FBCM) terminal 2G (wiring harness-side).

  • Is the voltage 0 V?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G.

    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 power supply.

  • Repair or replace the malfunctioning part.

    If there is no common connector:
  • Repair or replace the wiring harness which has a short to power supply.

Go to Step 8.

6

INSPECT FOR OPEN CIRCUIT IN AUTO LIGHT SENSOR/RAIN SENSOR CIRCUIT
  • Verify that the auto light sensor/rain sensor and front body control module (FBCM) connectors are disconnected.

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].)

  • Inspect the wiring harness for continuity between auto light sensor/rain sensor terminal A (wiring harness-side) and front body control module (FBCM) terminal 2G (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 auto light sensor/rain sensor terminal A and front body control module (FBCM) terminal 2G.

    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 8.

7

PERFORM DTC INSPECTION AND VERIFY AUTO LIGHT SENSOR/RAIN SENSOR MALFUNCTION

Yes

Replace the auto light sensor/rain sensor, then go to the next step.

(See RAIN SENSOR REMOVAL/INSTALLATION.)

No

Go to Step 9.

8

VERIFY THAT REPAIRS HAVE BEEN COMPLETED

Yes

Repeat the inspection from Step 1.

Go to the next step.

No

Go to the next step.

9

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 [FRONT BODY CONTROL MODULE (FBCM)].)

No

DTC troubleshooting completed.




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