DTC U3003:16 [RADAR UNIT]

id1502a6023500

Description	Radar unit power supply voltage decreases
Detection condition	• Radar unit power supply voltage is 9 V or less during engine start.
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	• DTCs are stored in the PCM • Battery malfunction • Generator malfunction • IG1 relay malfunction • Short to ground in wiring harness between MAIN 200 A fuse and IG1 relay terminal D • Open circuit in wiring harness between battery positive terminal and IG1 relay terminal D • Radar unit connector or terminal malfunction • Short to ground in wiring harness between IG1 relay terminal C and radar unit terminal E • C/U IG1 15 A fuse malfunction • Open circuit in wiring harness between IG1 relay terminal C and radar unit terminal E • Radar unit malfunction

Diagnostic Procedure

Step	Inspection		Action
1	VERIFY PCM DTCs • Retrieve the PCM DTCs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.5T)].) • Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [PCM (SKYACTIV-G 2.5T)].)
1		No	Go to the next step.
2	INSPECT BATTERY • Inspect the battery. (See BATTERY INSPECTION.) • Is the battery normal?	Yes	Go to the next step.
2		No	Replace/charge the battery, then go to Step 10. (See BATTERY RECHARGING.) (See BATTERY REMOVAL/INSTALLATION.)
3	INSPECT GENERATOR • Inspect the generator. (See GENERATOR INSPECTION [WITHOUT i-ELOOP (SKYACTIV-G 2.5T)].) (See GENERATOR INSPECTION [WITH i-ELOOP (SKYACTIV-G 2.5T)].) • Is the generator normal?	Yes	Go to the next step.
3		No	Replace the generator, then go to Step 10. (See GENERATOR REMOVAL/INSTALLATION [WITHOUT i-ELOOP (SKYACTIV-G 2.5T)].) (See GENERATOR REMOVAL/INSTALLATION [WITH i-ELOOP (SKYACTIV-G 2.5T)].)
4	INSPECT IG1 RELAY • Switch the ignition off. • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Remove the IG1 relay. (See RELAY LOCATION.) • Inspect the IG1 relay. (See RELAY INSPECTION.) • Is the IG1 relay normal?	Yes	Go to the next step.
4		No	Replace the IG1 relay, then go to Step 10. (See RELAY LOCATION.)
5	INSPECT IG1 RELAY CIRCUIT FOR SHORT TO GROUND • Verify that the IG1 relay is removed. • Inspect for continuity between IG1 relay terminal D (wiring harness-side) and body ground. • Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between MAIN 200 A fuse and IG1 relay terminal D. 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. • Replace the fuse. Go to Step 10.
5		No	Go to the next step.
6	INSPECT IG1 RELAY CIRCUIT FOR OPEN CIRCUIT • Verify that the IG1 relay is removed. • Inspect for continuity between battery positive terminal and IG1 relay terminal D (wiring harness-side). • Is there continuity?	Yes	Go to the next step.
6		No	Refer to the wiring diagram and verify whether or not there is a common connector between battery positive terminal and IG1 relay terminal D. 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 10.
7	INSPECT RADAR UNIT CONNECTOR CONDITION • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Remove front bumper. (See FRONT BUMPER REMOVAL.) (See FRONT BUMPER INSTALLATION.) • Disconnect the radar unit 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.
7		No	Repair or replace the connector, then go to Step 10.
8	INSPECT IG1 RELAY CIRCUIT FOR SHORT TO GROUND • Verify that the IG1 relay is removed. • Verify that the radar unit connector is disconnected. • Inspect for continuity between the following terminals (wiring harness-side) and body ground: ? IG1 relay terminal C ? Radar unit terminal E • Is there continuity?	Yes	Go to the next step.
8		No	Inspect the C/U IG1 15 A fuse. • If the fuse is blown: ? Refer to the wiring diagram and verify whether or not there is a common connector between C/U IG1 15 A fuse and radar unit terminal E. 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. • Replace the fuse. • If the fuse is damaged: ? Replace the fuse. • If the fuse is normal: ? Refer to the wiring diagram and verify whether or not there is a common connector between IG1 relay terminal C and C/U IG1 15 A fuse. 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 10.
9	INSPECT IG1 RELAY CIRCUIT FOR SHORT TO GROUND • Verify that the IG1 relay is removed. • Verify that the radar unit connector is disconnected. • Inspect for continuity between IG1 relay terminal C (wiring harness-side) and radar unit terminal E (wiring harness-side). • Is there continuity?	Yes	Go to the next step.
9		No	Inspect the C/U IG1 15 A fuse. • If the fuse is damaged: ? Replace the fuse. • If the fuse is normal: ? Refer to the wiring diagram and verify whether or not there is a common connector between IG1 relay terminal C and radar unit terminal E. 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 the next step.
10	VERIFY THAT REPAIRS HAVE BEEN COMPLETED • Always reconnect all disconnected connectors. • Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Clear the DTC for the radar unit using the M-MDS. (See CLEARING DTC [RADAR UNIT].) • Retrieve the radar unit DTCs using the M-MDS. (See DTC INSPECTION [RADAR UNIT].) • Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the radar unit. (See RADAR UNIT REMOVAL/INSTALLATION.) Go to the next step.
10		No	Go to the next step.
11	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 [RADAR UNIT].)
11		No	DTC troubleshooting completed.