Nissan Murano: Dtc/circuit Diagnosis / U1040 Eng Comm Circuit

Nissan Murano (Z52) 2015-2024 Service Manual / Engine / Engine Control System :: Vq35de / Dtc/circuit Diagnosis / U1040 Eng Comm Circuit

DTC Description

DTC DETECTION LOGIC

When ECM unable to transmit engine communication signal.

DTC

CONSULT screen terms

(Trouble diagnosis content) 		DTC detection condition
U1040 Engine communication line Diagnosis condition Ignition switch ON
Signal (terminal) Engine communication signal
Threshold ECM unable to transmit engine communication signal
Diagnosis delay time —

POSSIBLE CAUSE

  • Harness and connectors (Engine communication line is open or shorted.)

  • ECM

FAIL-SAFE

Engine operating condition in fail-safe mode
Fail safe mode Nissan Murano Vehicle behavior
Engine communication line ECM operates active grille shutter to fully-open position.
DTC Confirmation Procedure

PRECONDITIONING

If another DTC Confirmation Procedure is conducted just before this procedure, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

>>

GO TO 2.

PERFORM DTC CONFIRMATION PROCEDURE

  1. Turn ignition switch ON and wait at least 10 seconds.

  2. Check 1st trip DTC.

Is 1st trip DTC detected?

YES>>

Proceed to Diagnosis Procedure.

NO>>

To check malfunction symptom before repair: Refer to Intermittent Incident.

NO>>

Confirmation after repair: INSPECTION END

Diagnosis Procedure

CHECK ACTIVE GRILLE SHUTTER SIGNAL CIRCUIT

  1. Turn ignition switch OFF.

  2. Disconnect ECM harness connector.

  3. Disconnect active grille shutter harness connector.

  4. Check the continuity between ECM harness connector and active grille shutter harness connector.

    + − Continuity
    ECM Active grille shutter
    Connector Terminal Connector Terminal
    F79 99 E238 3 Existed

  5. Also check harness for short to ground and short to power.

Is the inspection result normal?

YES>>

INSPECTION END

NO>>

Repair or replace error-detected parts.

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