DTC B0021-1A: Decreased Resistance In The Left Side Curtain Airbag First Inflator (2017)

Special Tools Required 

SRS Short Canceller 070AZ-SAA0100 

NOTE: 

• BEFORE DOING THIS TROUBLESHOOTING PROCEDURE, FIND OUT IF THE VEHICLE WAS IN A COLLISION. IF SO, VERIFY THAT ALL THE REQUIRED COMPONENTS WERE REPLACED WITH NEW COMPONENTS OF THE CORRECT PART NUMBER AND WERE PROPERLY INSTALLED .
• Before doing this troubleshooting procedure, review SRS PRECAUTIONS AND PROCEDURES , GENERAL TROUBLESHOOTING INFORMATION , and 12 VOLT BATTERY TERMINAL DISCONNECTION AND RECONNECTION .

1. Problem verification

   - 1. Clear the DTCs with the HDS.

   - 2. Turn the vehicle to the ON mode, then wait for 10 seconds.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   B0021-1A: Decreased resistance in the left side curtain airbag first inflator

   Is DTC B0021-1A indicated?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures. If another DTC is indicated, troubleshoot the DTC.

2. Left side curtain airbag inflator check

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

   - 3. Remove the headliner.

   - 4. Disconnect the following connector.

   Left side curtain airbag inflator 2P connector (on the left side wire harness)

   - 5. Reconnect the negative cable to the 12 volt battery.

   - 6. Clear the DTCs with the HDS.

   - 7. Turn the vehicle to the ON mode, then wait for 10 seconds.

   - 8. Check for DTCs with the HDS.

   DTC Description	DTC
   B0021-1A Decreased resistance in the left side curtain airbag inflator

   Is DTC B0021-1A indicated?

   YES 

   Go to step 3.

   NO 

   Faulty left side curtain airbag inflator; REPLACE THE LEFT SIDE CURTAIN AIRBAG , then clear the DTC.

3. Shorted wire check (LCA+ line to LCA- line)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

   - 3. Disconnect the following connector.

   SRS unit connector B (39P)

   - 4. Connect the SRS short canceller to SRS unit connector B (39P) terminals No. 9 and No. 10.

   - 5. Measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Left side curtain airbag inflator 2P connector (on the left side wire harness): disconnected
   	SRS unit connector B (39P): disconnected
   	SRS unit connector B (39P) No. 9 and No. 10: connected to SRS short canceller
   Test point 1	SRS unit connector B (39P) No. 9 - Refer to: SRS UNIT CONNECTOR FOR INPUTS AND OUTPUTS (2014 2015), or SRS UNIT CONNECTOR FOR INPUTS AND OUTPUTS (2017)
   Test point 2	SRS unit connector B (39P) No. 10 - Refer to: SRS UNIT CONNECTOR FOR INPUTS AND OUTPUTS (2014 2015), or SRS UNIT CONNECTOR FOR INPUTS AND OUTPUTS (2017)

   Is there an open circuit, or at least 1 MΩ?

   YES 

   The LCA+ and LCA- wires are OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or REPLACE THE SRS UNIT .

   NO 

   Short to another wire in the left or right side wire harness; replace the faulty harness, then clear the DTC.