NATS (Nissan Anti-Theft System) / Gasoline engine — Trouble Diagnoses (Cont'd) — Diagnostic Procedure 2 (Cont'd) — Communication line tests (Supplement-VII)
EL-7067flowchartProcedure 2 continuation: short-to-power (F) + short-to-ground (G) checks on communication line, then ECM signal scope check (H). Signal expected within 750 msec of ign-on. NG paths route to ECM or IMMU replacement.
Trouble Diagnoses (Cont'd) — Procedure 2 (Cont'd)
Procedure 2 — Communication line tests (F/G/H)
1
[F] CHECK COMMUNICATION LINE BATTERY SHORT CIRCUIT. 1) Disconnect ECM connector and IMMU connector. 2) Turn ignition switch to ON. 3) Check voltage between IMMU terminal 1 and ground. No voltage should exist.
NG
Repair harness. Ref. part No. C4.
OK
2
[G] CHECK COMMUNICATION LINE GROUND SHORT CIRCUIT. 1) Disconnect ECM connector and IMMU connector. 2) Turn ignition switch OFF. 3) Check continuity between IMMU terminal 1 and ground. No continuity should exist.
NG
same as step 1
OK
3
[H] SIGNAL FROM ECM TO IMMU CHECK. 1) Check the signal between ECM terminal 88 and ground with CONSULT-II or oscilloscope when ignition switch is turned 'ON'. 2) Make sure signals which are shown in the figure below can be detected during 750 msec just after ignition switch is turned 'ON'.
NG
• ECM is malfunctioning. 1) Replace ECM. Ref. part No. B. 2) Perform initialization with CONSULT-II. For the initialization procedure, refer to 'CONSULT-II operation manual NATS'.
• ECM is malfunctioning. 1) Replace ECM. Ref. part No. B. 2) Perform initialization with CONSULT-II. For the initialization procedure, refer to 'CONSULT-II operation manual NATS'.
OK
4
• IMMU is malfunctioning. 1) Replace IMMU. Ref. part No. A. 2) Perform initialization with CONSULT-II. For the initialization procedure, refer to 'CONSULT-II operation manual NATS'.
NOTE
Continuation of Procedure 2. After harness checks (B/C/D/E on previous page), this page checks short-to-power (F) and short-to-ground (G) on the communication line itself, then validates the ECM-to-IMMU signal with an oscilloscope (H).
If H fails (no signal at ECM pin 88 within 750 msec of ignition ON), ECM is bad — replace ECM + re-init. If H passes but the system still won't operate, IMMU is bad — replace IMMU + re-init.