NATS / Gasoline engine — Diagnostic Procedure 2 (Cont'd) — Communication short/ground checks + ECM signal
EL-7067flowchartECM-to-IMMU init signal is a single positive pulse within the first 750 ms after ignition ON — captured with CONSULT-II scope mode or a regular DSO at 5 V/div, 10 ms/div, auto-trigger. NG paths point at C4 (comm-line harness short) or A/B (IMMU/ECM replacement).
NATS (Nissan Anti-Theft System) / Gasoline engine
Trouble Diagnoses (Cont'd) — Diagnostic Procedure 2
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 ㊵ 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".