Measure the resistance between connector (3AG) in the test harness AG and chassis ground.
Connector & terminal
(3AG) No. 17 — (3AG) No. 19:
(3AG) No. 17 — Chassis ground:
(3AG) No. 19 — Chassis ground:
Is the resistance 1 MΩ or more?
Replace the airbag rear harness along with body harness.