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 Description
DTC
B0021-13 Open or increased resistance in the left side curtain airbag first inflator
Measure the resistance between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Left side curtain airbag inflator 2P connector (on the floor wire harness): disconnected
SRS unit connector B (39P): disconnected
SRS unit connector B (39P) terminals No. 1 and No. 2: jumped
Test point 1
Left side curtain airbag inflator 2P connector No. 1 (on the floor wire harness)
Test point 2
Left side curtain airbag inflator 2P connector No. 2 (on the floor wire harness)
Is there 1.0 ? or less?
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. If the DTC does not clear, replace the floor wire harness.?
NO
Open in the floor wire harness; replace the floor wire harness, then clear the DTC.?