1) Turn the ignition switch to OFF, disconnect the battery ground cable, and wait for 60 seconds or more.
2) Check that the airbag control module and the connectors (AB6, AB17, AB18) are securely connected.
Are there poor contact of connectors (AB6, AB17, AB18)?
If the faulty connector contact remains, replace the airbag main harness along with body harness or replace the airbag control module.