System malfunction location

• U101C:00: Radar sensor communication error

• U101D:00: Error signal received from radar sensor

• U1A00:88: CAN communication error (Bus off)

Detection condition

• Communication error between radar sensor and vehicle control module (V/C-module)

Fail-safe

• Inhibits the Mazda radar cruise control (MRCC) system control

• Inhibits the forward obstruction warning (FOW) system control

Possible cause

• Connector or terminal malfunction

• Short circuit to power supply or ground in wiring harness between radar sensor and vehicle control module (V/C-module)

• Open circuit in wiring harness between radar sensor and vehicle control module (V/C-module)

• Radar sensor malfunction

• Vehicle control module (V/C-module) malfunction

Step

Inspection

Action

1

• Switch the ignition off (LOCK).

• Disconnect the negative battery cable.

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

• Remove the front bumper.

  (See FRONT BUMPER REMOVAL/INSTALLATION.)

• Disconnect the radar sensor connector.

• Inspect the radar sensor connector. (Corrosion, damage, and disconnected pins)

• Is there any malfunction of the radar sensor connector?

Yes

Replace the malfunctioning part, then go to Step 8.

No

Go to the next step.

2

• Remove the front scuff plate (RH).

  (See FRONT SCUFF PLATE REMOVAL/INSTALLATION.)

• Remove the front side trim (RH).

  (See FRONT SIDE TRIM REMOVAL/INSTALLATION.)

• Disconnect the vehicle control module (V/C-module) connector.

• Inspect the vehicle control module (V/C-module) connector. (Corrosion, damage, and disconnected pins)

• Is there any malfunction of the vehicle control module (V/C-module) connector?

Yes

Replace the malfunctioning part, then go to Step 8.

No

Go to the next step.

3

• Verify that the radar sensor and vehicle control module (V/C-module) connectors are disconnected.

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

• Vehicle control module (V/C-module) terminal AB

• Vehicle control module (V/C-module) terminal AD

NOTE:

• Inspect for continuity while shaking the wiring harness between the radar sensor and vehicle control module (V/C-module).

• Is there continuity?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between radar sensor and vehicle control module (V/C-module).

• 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.

• Repair or replace the wiring harness which has a short to ground.

Go to Step 8.

No

Go to the next step.

4

• Verify that the radar sensor and vehicle control module (V/C-module) connectors are disconnected.

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

• Radar sensor terminal D—vehicle control module (V/C-module) AB

• Radar sensor terminal C—vehicle control module (V/C-module) AD

NOTE:

• Inspect for continuity while shaking the wiring harness between the radar sensor and vehicle control module (V/C-module).

• 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 radar sensor and vehicle control module (V/C-module).

• 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.

• Repair or replace the wiring harness which has an open circuit.

Go to Step 8.

5

• Verify that the radar sensor and vehicle control module (V/C-module) connectors are disconnected.

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

• Vehicle control module (V/C-module) terminals AB and AD

NOTE:

• Inspect for continuity while shaking the wiring harness between the radar sensor and vehicle control module (V/C-module).

• Is there continuity?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between radar sensor and vehicle control module (V/C-module).

• 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 circuit.

• Repair or replace the malfunctioning part.

• Repair or replace the wiring harness which has a short circuit.

Go to Step 8.

No

Go to the next step.

6

• Verify that the radar sensor and vehicle control module (V/C-module) connectors are disconnected.

• Connect 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 following terminals (wiring harness-side):

• Vehicle control module (V/C-module) terminal AB

• Vehicle control module (V/C-module) terminal AD

NOTE:

• Measure the voltage while shaking the wiring harness between the radar sensor and vehicle control module (V/C-module).

• 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 radar sensor and vehicle control module (V/C-module).

• 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.

• Repair or replace the wiring harness which has a short to power supply.

Go to Step 8.

7

• Switch the ignition off (LOCK).

• Disconnect the negative battery cable.

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

• Reconnect all disconnected connectors.

• Clear vehicle control module (V/C-module) DTCs using the M-MDS.

  (See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].)

• Switch the ignition ON (engine on).

• Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS.

  (See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].)

• Is the same DTC present?

Yes

Replace the radar sensor, then go to the next step.

(See RADAR SENSOR REMOVAL/INSTALLATION [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM].)

No

Go to the next step.

8

• Clear vehicle control module (V/C-module) DTCs using the M-MDS.

  (See CLEARING DTC [VEHICLE CONTROL MODULE (V/C-MODULE)].)

• Switch the ignition ON (engine on).

• Perform the vehicle control module (V/C-module) DTC inspection using the M-MDS.

  (See DTC INSPECTION [VEHICLE CONTROL MODULE (V/C-MODULE)].)

• Is the same DTC present?

Yes

Repeat the inspection from Step 1.

• If the malfunction does not recur, go to the next step.

• If the malfunction recurs, replace the vehicle control module (V/C-module).

  (See VEHICLE CONTROL MODULE (V/C-MODULE) REMOVAL/INSTALLATION [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM].)

Go to the next step.

No

Go to the next step.

9

• Verify other DTCs displayed.

• Are any other DTCs output?

Yes

Perform the corresponding DTC inspection.

No

DTC troubleshooting completed.