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Home >> Mazda >> 2021 >> CX-3 AWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> On-Board Diagnostic - Connectivity Master Unit >> DTC B1087-87: Communication Error With Commander Switch (Connectivity Master Unit) >> Diagnostic Procedure

Diagnostic Procedure

DTC B1087:87 (CONNECTIVITY MASTER UNIT) DIAGNOSTIC PROCEDURE

Step Inspection Action
1 INSPECT COMMANDER SWITCH CONNECTOR CONDITION
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
  • Disconnect the commander switch

    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 COMMANDER SWITCH CIRCUIT FOR SHORT TO GROUND
  • Verify that the commander switch and connectivity master unit (CMU) connectors are disconnected.
  • Inspect for continuity between commander switch terminal E (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Refer to the wiring diagram and verify if there is a common connector between connectivity master unit (CMU) terminal 2K and commander switch terminal E. If there is a common connector:
  • Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for short to ground to determine the malfunctioning location.
  • Repair or replace the malfunctioning location.

    If there is no common connector:

  • Repair or replace the wiring harness which is shorted to ground.

Go to Step 7.
No Go to the next step.
4 INSPECT COMMANDER SWITCH CIRCUIT FOR SHORT TO POWER SUPPLY
  • Verify that the commander switch 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 commander switch terminal E (wiring harness-side).
  • 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 connectivity master unit (CMU) terminal 2K and commander switch terminal E. If there is a common connector:
  • Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for short to power supply to determine the malfunctioning location.
  • Repair or replace the malfunctioning location.

    If there is no common connector:

  • Repair or replace the wiring harness which is shorted to power supply.

Go to Step 7.
5 INSPECT COMMANDER SWITCH CIRCUIT FOR OPEN CIRCUIT
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
  • Verify that the commander switch and connectivity master unit (CMU) connectors are disconnected.
  • Inspect the wiring harness for continuity between connectivity master unit (CMU) terminal 2K (wiring harness-side) and commander switch terminal E (wiring harness-side).
  • Is there continuity?
 Yes Go to the next step.
No Refer to the wiring diagram and verify if there is a common connector between connectivity master unit (CMU) terminal 2K and commander switch terminal E. If there is a common connector:
  • Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for an open circuit to determine the malfunctioning location.
  • Repair or replace the malfunctioning location.

    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 COMMANDER SWITCH DEPENDING ON REPEATABILITY
 Yes Replace the commander switch, then go to the next step.
(See COMMANDER SWITCH 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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