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DTC U0231:68 [BCM]

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2016 – MX-5 – Body and Accessories

DTC U0231:68 [BCM]

Description

Communication error with auto light sensor/rain sensor

Detection condition

  • BCM 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

    Auto light system

  • Continue the controls prior to the auto light malfunction detection.

    Auto wiper system

  • Continue the controls prior to the wiper malfunction detection.

Possible cause

  • Auto light sensor/rain sensor connector or terminal malfunction

  • BCM connector or terminal malfunction

  • Short to ground in wiring harness between auto light sensor/rain sensor terminal A and BCM terminal 3X

  • Short to power supply in wiring harness between auto light sensor/rain sensor terminal A and BCM terminal 3X

  • Open circuit in wiring harness between auto light sensor/rain sensor terminal A and BCM terminal 3X

  • Auto light sensor/rain sensor malfunction

  • BCM malfunction

Diagnostic Procedure

Step

Inspection

Action

1

VERIFY BCM DTCs AGAIN

  • Clear the DTC for the BCM using the M-MDS.

    (See CLEARING DTC [BCM].)

  • Operate the light switch to the AUTO position.

  • Operate the wiper and washer switch to the AUTO position.

  • Switch the ignition ON (engine off or on) and wait for 5 s or more.

  • Retrieve the BCM DTCs using the M-MDS.

    (See DTC INSPECTION [BCM].)

  • Is the same DTC displayed?

Yes

Go to the next step.

No

Go to Step 9.

2

INSPECT AUTO LIGHT SENSOR/RAIN SENSOR CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • 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 BCM CONNECTOR CONDITION

  • Disconnect the BCM 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 BCM connectors are disconnected.

  • Inspect for continuity between BCM terminal 3X (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 BCM terminal 3X.

    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 AUTO LIGHT SENSOR/RAIN SENSOR CIRCUIT FOR SHORT TO POWER SUPPLY

  • Verify that the auto light sensor/rain sensor and BCM connectors are disconnected.

  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

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

  • Measure the voltage at the BCM terminal 3X (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 BCM terminal 3X.

    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 AUTO LIGHT SENSOR/RAIN SENSOR CIRCUIT FOR OPEN CIRCUIT

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Verify that the auto light sensor/rain sensor and BCM connectors are disconnected.

  • Inspect the wiring harness for continuity between auto light sensor/rain sensor terminal A (wiring harness-side) and BCM terminal 3X (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 BCM terminal 3X.

    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

VERIFY IF MALFUNCTIONING LOCATION IS AUTO LIGHT SENSOR/RAIN SENSOR DEPENDING ON REPEATABILITY

  • Always reconnect all disconnected connectors.

  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Clear the DTC for the BCM using the M-MDS.

    (See CLEARING DTC [BCM].)

  • Operate the light switch to the AUTO position.

  • Operate the wiper and washer switch to the AUTO position.

  • Switch the ignition ON (engine off or on) and wait for 5 s or more.

  • Retrieve the BCM DTCs using the M-MDS.

    (See DTC INSPECTION [BCM].)

  • Is the same DTC displayed?

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

  • Always reconnect all disconnected connectors.

  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Clear the DTC for the BCM using the M-MDS.

    (See CLEARING DTC [BCM].)

  • Operate the light switch to the AUTO position.

  • Operate the wiper and washer switch to the AUTO position.

  • Switch the ignition ON (engine off or on) and wait for 5 s or more.

  • Retrieve the BCM DTCs using the M-MDS.

    (See DTC INSPECTION [BCM].)

  • Is the same DTC displayed?

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 [BCM].)

No

DTC troubleshooting completed.

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