DTC B0021-1A: Left Curtain Deployment Control 1 - Circuit resistance below threshold: Action

WARNING: Do not measure the resistance of a deployable device using any other method than that described below

NOTE:

The airbag connector has a locking plunger (orange tab) which should only fully lock when the two connectors are securely mated, male to female. If the plunger can move to the locked position easily when not mated (ie: using reasonable pressure), then this indicates that the connector is damaged. Replace the wiring harness as necessary

A shorting bar inside the connector (deployable device side) intentionally creates a short circuit until the wiring harness connector is installed AND the plunger is engaged
Left side air curtain resistance specification should be greater than 1.70 ohms and less than 3.28 ohms at -40°C to 85°C

Using the Jaguar Land Rover approved diagnostic equipment, check datalogger signal - Deployment Control 20 Resistance (0x5B3A). If the resistance is too low, disconnect and reconnect the left side air curtain connector, making sure that the connector plunger is correctly engaged. Clear the DTCs and retest
Disconnect the left side air curtain connector and apply light pressure to the connector plunger. If the plunger moves to the engaged position the connector is damaged. Replace the wiring harness as necessary
Refer to the electrical circuit diagrams and check the left side air curtain circuit for short circuit between power and ground
Using the Jaguar Land Rover approved diagnostic equipment, clear the DTCs and retest