DTC B0021-1A:Decreased Resistance in the Left Side Curtain Airbag First Inflator (2015-17)

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 that they were properly installed - Refer to: SRS Component Replacement/Inspection After Deployment .
• Review SRS Precautions and Procedures .
• Review General Troubleshooting Information
• Review information pertaining to 12 Volt Battery Terminal Disconnection and Reconnection

Before replacing the SRS unit: 

• Check the SRS unit software version with the HDS. If the software version is not the latest, update the SRS unit software , and retest.

DTC (SRS)

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 - Refer to: How to Troubleshoot the SRS . 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 first inflator

   Is DTC B0021-1A indicated?

   YES 

   Go to step 3.

   NO 

   Short to another wire in the 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. 1 and No. 2.

   - 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. 1 and No. 2: connected to SRS short canceller
   Test point 1	SRS unit connector B (39P) No. 1 - Refer to: SRS Unit Connector for Inputs and Outputs
   Test point 2	SRS unit connector B (39P) No. 2 - Refer to: SRS Unit Connector for Inputs and Outputs

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

   YES 

   The LCA+ and LCA- wires are OK. Faulty SRS unit or poor connection at SRS unit connector B (39P) and the SRS unit. Check the connection; if the connection is OK, replace the SRS unit - Refer to: SRS Unit Removal and Installation . If the DTC does not clear, replace the left or right side wire harness.

   NO 

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