Diagnostic Procedure

WARNING: This page is about a different car, the 2014 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DTC U101C:00, U101D:00, U1A00:88 (VEHICLE CONTROL MODULE) DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT RADAR SENSOR CONNECTOR 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.
1		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. 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.
2		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	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). 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.
3		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.
4		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). 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.
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	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). 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 circuit. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short circuit. Go to Step 8.
5		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-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.
6		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). 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.
7	PERFORM DTC INSPECTION FOR VEHICLE CONTROL MODULE (V/C-MODULE) 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] .)
7		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 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.
8		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.
9		No	DTC troubleshooting completed.