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DTC B1238:87 [CONNECTIVITY MASTER UNIT]

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2016 – MX-5 – Body and Accessories

DTC B1238:87 [CONNECTIVITY MASTER UNIT]

Description

HD image transfer circuit malfunction

Detection condition

  • The connectivity master unit (CMU) detects a communication error in the HD image transfer circuit for 20 times with the ignition switched ON (engine off or on).

Fail-safe

Not applicable

Possible cause

  • Tuner and amp unit (TAU) connector or terminal malfunction

  • Connectivity master unit (CMU) connector or terminal malfunction

  • Short to ground in wiring harness between the following terminals:

    • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

    • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

  • Short to power supply in wiring harness between the following terminals:

    • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

    • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

  • Open circuit in wiring harness between the following terminals:

    • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

    • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

  • Tuner and amp unit (TAU) malfunction

  • Connectivity master unit (CMU) malfunction

Diagnostic Procedure

Step

Inspection

Action

1

INSPECT TUNER AND AMP UNIT (TAU) CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Disconnect the tuner and amp unit (TAU) 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.

2

INSPECT CONNECTIVITY MASTER UNIT (CMU) CONNECTOR CONDITION

  • Disconnect the connectivity master unit (CMU) 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.

3

INSPECT HD IMAGE TRANSFER CIRCUIT FOR SHORT TO GROUND

  • Verify that the tuner and amp unit (TAU) and connectivity master unit (CMU) connectors are disconnected.

  • Inspect for continuity between the following terminals (wiring harness-side) and body ground:

    • Tuner and amp unit (TAU) terminal 1W

    • Tuner and amp unit (TAU) terminal 1X

  • Is there continuity?

Yes

Refer to the wiring diagram and verify if there is a common connector between the following terminals:

  • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

  • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

    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 7.

No

Go to the next step.

4

INSPECT HD IMAGE TRANSFER CIRCUIT FOR SHORT TO POWER SUPPLY

  • Verify that the tuner and amp unit (TAU) and connectivity master unit (CMU) 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 following terminals (wiring harness-side):

    • Tuner and amp unit (TAU) terminal 1W

    • Tuner and amp unit (TAU) terminal 1X

  • Is the voltage 0 V?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify if there is a common connector between the following terminals:

  • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

  • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

    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 7.

5

INSPECT HD IMAGE TRANSFER CIRCUIT FOR OPEN CIRCUIT

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Verify that the tuner and amp unit (TAU) and connectivity master unit (CMU) connectors are disconnected.

  • Inspect for continuity between the following terminals (wiring harness-side):

    • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

    • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

  • Is there continuity?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify if there is a common connector between the following terminals:

  • Connectivity master unit (CMU) terminal 2O—Tuner and amp unit (TAU) terminal 1W

  • Connectivity master unit (CMU) terminal 2P—Tuner and amp unit (TAU) terminal 1X

    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.

6

VERIFY IF MALFUNCTIONING LOCATION IS TUNER AND AMP UNIT (TAU) DEPENDING ON REPEATABILITY

Yes

Replace the tuner and amp unit (TAU), then go to the next step.

(See TUNER AND AMP UNIT (TAU) REMOVAL/INSTALLATION.)

No

Go to Step 8.

7

VERIFY THAT REPAIRS HAVE BEEN COMPLETED

Yes

Repeat the inspection from Step 1.

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.

(See DTC TABLE [CONNECTIVITY MASTER UNIT].)

No

DTC troubleshooting completed.

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