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Home >> Mazda >> 2017 >> CX-5 Grand Select, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 38 (On-Board Diagnostic [Front Body Control Module (FBCM)]) >> DTC U0231-68: Communication Error With Auto-Light Sensor/Rain Sensor >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.
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 CONDITION  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 CONDITION 
  • 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 AUTO-LIGHT SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO GROUND 
  • 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 (vehicle wiring harness side) and body ground.
  • Is there continuity?
 Yes Repair or replace the wiring harness which is shorted to ground, then go to Step 8.
No Go to the next step.
5 INSPECT AUTO-LIGHT SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO POWER SUPPLY 
  • Verify that the auto-light sensor/rain sensor and front body control module (FBCM) connectors are disconnected.
  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)

  • Switch the ignition ON (engine off or on).
  • Measure the voltage at front body control module (FBCM) terminal 2G (vehicle wiring harness side).
  • Is the voltage 0 V  ?
 Yes Go to the next step.
No Repair or replace the wiring harness which is shorted to power supply, then go to Step 8.
6 INSPECT AUTO-LIGHT SENSOR/RAIN SENSOR CIRCUIT FOR OPEN CIRCUIT 
  • Verify that the auto-light sensor/rain sensor and front body control module (FBCM) connectors are disconnected.
  • Switch the ignition to off.
  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)

  • Inspect the wiring harness for continuity between auto-light sensor/rain sensor terminal A (vehicle wiring harness side) and front body control module (FBCM) terminal 2G (vehicle wiring harness side).
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace the wiring harness which has an open circuit, then go to Step 8.
7 PERFORM DTC INSPECTION AND VERIFY IF MALFUNCTIONING PART IS AUTO-LIGHT SENSOR/RAIN SENSOR  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 Replace the front body control module (FBCM), then go to the next step.
(See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION .)
No Go to the next step.
9 VERIFY IF OTHER DTCs DISPLAYED 
  • Are any other DTCs displayed?
 Yes Repair 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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