Electronic Control Module (ECM) Power & Ground Circuit Test

Turn ignition on. Locate ECM behind glove box. Measure voltage between ground and ECM harness connector terminal No. 16 (Orange wire). See Fig 1 . Voltage should be 0.8-1.0 volts. Measure voltage between ground and ECM harness connector terminals No. 49 (White wire), No. 59 (White wire), and No. 109 (White wire). Battery voltage should be present. If voltages are as specified, go to step 3). If voltages are not as specified, go to next step.
Check ECM (ECCS) relay. Relay is located in fuse box, at left front of engine compartment. See RELAYS under RELAYS & SOLENOIDS. Check Green fusible link. Fusible link is located in fusible link box, next to battery. Ensure continuity exists between ECM relay and positive battery terminal. Ensure continuity exists between ECM harness connector terminal No. 16 (Orange wire) and ECM relay.
Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 10 (Black wire), No. 20 (Black wire), No. 50 (Black wire), No. 60 (Black wire), No. 107 (Black wire), No. 108 (Black wire), and No. 116 (Black wire). Continuity should exist. If continuity does not exist, check chassis and engine ground connections. If ground connections are okay, repair harness or connectors.

Fig 1: ECM Connector Terminals (As Viewed From Wiring Harness Side)

Courtesy of NISSAN MOTOR CO., U.S.A.