Lexus NX manuals

Lexus NX: Diagnosis System

Lexus NX Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / Diagnosis System

DIAGNOSIS SYSTEM

DESCRIPTION

(a) The certification ECU (smart key ECU assembly) and hybrid vehicle control ECU control the vehicle immobiliser system functions. Immobiliser system data and Diagnostic Trouble Codes (DTCs) can be read through the vehicle Data Link Connector 3 (DLC3).

In some cases, a malfunction may be occurring in the immobiliser system even though the security indicator light is not illuminated.

When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform repairs.

CHECK DLC3

(a) Check the DLC3.

Click here

INSPECT AUXILIARY BATTERY VOLTAGE

(a) Measure the auxiliary battery voltage with the power switch off.

Standard voltage:

11 to 14 V

If the voltage is below 11 V, recharge or replace the auxiliary battery.

START FUNCTION PROBLEM SYMPTOMS

Symptom

Suspected Area

Component Malfunction

Possible Output DTCs

Related Data List Item

Hybrid control system cannot be started*1

Certification ECU (smart key ECU assembly)

Open or short circuit inside ECU
  • B278A
  • B2799-790
  • B279A-186
  • # Codes
  • Immobilizer when IG=ON
  • Immobiliser
  • Master Key
  • Sub Key
  • BCC Malfunction
  • Abnormal Status
  • Different Encrypt Code
  • Different Serial Number
  • Frame Error
  • Response
  • Wireless Starter Com ID
  • Wireless C Code
  • Engine Start Condition
  • ID-BOX Sleep Condition
  • ID-BOX Start Condition
  • Engine Start Request
  • 3bit Code Request
  • S Code Check
  • L Code Check
  • Unlock Request Receive
  • Lock Request Receive
  • S Code Check (Past)
  • L Code Check (Past)
  • EFI Code Receive
  • EFI Communication

Hybrid control system cannot be started*1

ID code box (immobiliser code ECU)

Open or short circuit inside ECU
  • B2790
  • B2799-790
  • B279A-186
  • Immobilizer when IG=ON
  • Immobiliser
  • Master Key
  • Sub Key
  • BCC Malfunction
  • Abnormal Status
  • Different Encrypt Code
  • Different Serial Number
  • Frame Error
  • Response
  • ID-BOX Sleep Condition
  • ID-BOX Start Condition
  • Engine Start Request
  • 3bit Code Request
  • S Code Check
  • L Code Check
  • S Code Check (Past)
  • L Code Check (Past)
  • EFI Code Receive
  • EFI Communication

Hybrid vehicle control ECU

Open or short circuit inside ECU
  • B2799-790
  • B279A-186
  • B279C-185

EFI Code Receive

Hybrid control

Hybrid vehicle control ECU incompatible with installed immobiliser system

B279C-185
  • Engine Start Condition
  • EFI Code Receive

Power source mode cannot be changed*1

Power switch

Open or short circuit inside switch

B278A
  • Unlock Request Receive
  • Lock Request Receive

Certification ECU (smart key ECU assembly)

Open or short circuit inside ECU
  • B2271
  • B2274
  • Immobilizer when IG=ON
  • Immobiliser

Steering lock lock/unlock not possible*2

Steering lock ECU (steering lock actuator assembly)
  • Open or short circuit inside ECU
  • Actuator stuck
  • B2781
  • B2782
  • B2788
  • Unlock Request Receive
  • Lock Request Receive
  • *1: Refer to Problem Symptoms Table for Smart Access System with Push-button Start (for Start Function).

    Click here

  • *2: Refer to Problem Symptoms Table for Steering Lock System.

    Click here

READ NEXT:

 Dtc Check / Clear

DTC CHECK / CLEAR NOTICE: When using the Techstream with the power switch off, connect the Techstream to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until

 Data List / Active Test

DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a pa

 Diagnostic Trouble Code Chart

DIAGNOSTIC TROUBLE CODE CHART Immobiliser System DTC No. Detection Item Link B2779 Engine Starter Communication Malfunction B2784 Antenna Coil Open / Short B278A Sho

SEE MORE:

 Problem Symptoms Table

PROBLEM SYMPTOMS TABLE NOTICE: If the auxiliary battery voltage is low, the PTC heater, seat heater system (w/ Seat Heater System) and climate control seat system (w/ Climate Control Seat System) may not operate. When "High Power Consumption Partial Limit On AC/Heater Operation." is displayed on

 Inspection

INSPECTION PROCEDURE 1. INSPECT INTEGRATION CONTROL AND PANEL ASSEMBLY (ELECTRIC PARKING BRAKE SWITCH) (a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition 9 (LOK1) -16 (GND1) OFF(Release) 97.

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