DTC U101C:00, U101D:00, U1A00:88 [VEHICLE CONTROL MODULE (V/C-MODULE)]

id0102i0005600

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 smart brake support (SBS) system control •  Inhibits the distance recognition support system (DRSS) 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

Diagnostic Procedure

Step	Inspection		Action
1	INSPECT RADAR SENSOR CONNECTOR •  Switch the ignition to off. •  Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, 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	INSPECT VEHICLE CONTROL MODULE (V/C-MODULE) CONNECTOR •  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. (See VEHICLE CONTROL MODULE (V/C-MODULE) REMOVAL/INSTALLATION [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM].) •  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	INSPECT RADAR SENSOR CIRCUIT FOR SHORT TO GROUND •  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	If there is a common connector:If there is no common connector: 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	INSPECT RADAR SENSOR CIRCUIT FOR OPEN CIRCUIT •  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	If there is a common connector:If there is no common connector: 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	INSPECT RADAR SENSOR CIRCUIT FOR SHORT •  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	If there is a common connector:If there is no common connector: 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	INSPECT RADAR SENSOR CIRCUIT FOR SHORT TO POWER SUPPLY •  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-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, 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	If there is a common connector:If there is no common connector: 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	PERFORM DTC INSPECTION FOR VEHICLE CONTROL MODULE (V/C-MODULE) •  Switch the ignition off. •  Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, 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	VERIFY THAT REPAIRS HAVE BEEN COMPLETED •  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 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 THAT NO OTHER DTCs ARE PRESENT •  Verify other DTCs displayed. •  Are any other DTCs output?	Yes	Perform the corresponding DTC inspection.
		No	DTC troubleshooting completed.