Lexus NX: Power Source Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives IG signals and supplies power to the headlight ECU sub-assembly via the H-LP relay.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The lighting system (for Triple Beam Headlight) uses the LIN communication system and CAN communication system. First, confirm that there are no malfunctions in the LIN communication system and CAN communication system. Refer to the How to Proceed with Troubleshooting procedure.

    CAN communication system:

    Click here

    LIN communication system:

    Click here

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.
  • Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.

    Click here

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY - BATTERY AND BODY GROUND)

(a) Disconnect the A19 headlight ECU sub-assembly LH or A20 headlight ECU sub-assembly RH connector.

*A

Headlight ECU Sub-assembly LH

*B

Headlight ECU Sub-assembly RH

*a

Front view of wire harness connector

(to Headlight ECU Sub-assembly)

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Headlight ECU Sub-assembly LH

Tester Connection

Switch Condition

Specified Condition

A19-13 (ECUB) - Body ground

Power switch on (IG)

11 to 14 V

A19-4 (IG) - Body ground

Power switch on (IG)

11 to 14 V

Headlight ECU Sub-assembly RH

Tester Connection

Switch Condition

Specified Condition

A20-13 (ECUB) - Body ground

Power switch on (IG)

11 to 14 V

A20-4 (IG) - Body ground

Power switch on (IG)

11 to 14 V

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Headlight ECU Sub-assembly LH

Tester Connection

Condition

Specified Condition

A19-12 (GND) - Body ground

Always

Below 1 Ω

Headlight ECU Sub-assembly RH

Tester Connection

Condition

Specified Condition

A20-12 (GND) - Body ground

Always

Below 1 Ω

Result

Proceed to

OK

A

NG (Headlight ECU Sub-assembly LH)

B

NG (Headlight ECU Sub-assembly RH)

C

A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 7

B

2.

INSPECT HEADLIGHT DIMMER RELAY (H-LP LH/DIMMER [HI])

(a) Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.

(b) Inspect the headlight light dimmer relay (H-LP LH/DIMMER [HI]).

Click here

NG

REPLACE HEADLIGHT DIMMER RELAY (H-LP LH/DIMMER [HI])

OK

3.

CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - BATTERY)

(a) Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.

*a

Front view of wire harness connector

(to Headlight Light Dimmer Relay (H-LP LH/DIMMER [HI]))

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

Relay terminal 1 - Body ground

Power switch off

11 to 14 V

Relay terminal 5 - Body ground

Power switch off

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - HEADLIGHT ECU SUB-ASSEMBLY LH)

(a) Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.

(b) Disconnect the A19 headlight ECU sub-assembly LH connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Relay terminal 3 - A19-13 (ECUB)

Always

Below 1 Ω

Relay terminal 3 or A19-13 (ECUB) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU])

(a) Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.

(b) Remove the instrument panel junction block assembly.

Click here

(c) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

Click here

(d) Disconnect the 4B instrument panel junction block assembly connector.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Relay terminal 2 - A-15 (HRLY)

Always

Below 1 Ω

Relay terminal 2 or A-15 (HRLY) - Body ground

Always

10 kΩ or higher

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

6.

CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.

(b) Disconnect the 4B instrument panel junction block assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Relay terminal 2 - 4B-53

Always

Below 1 Ω

Relay terminal 2 or 4B-53 - Body ground

Always

10 kΩ or higher

OK

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

CHECK HEADLIGHT RELAY (H-LP RH)

(a) Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.

(b) Inspect the headlight light relay (H-LP RH).

Click here

NG

REPLACE HEADLIGHT RELAY (H-LP RH RELAY)

OK

8.

CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP RH] - BATTERY)

(a) Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.

*a

Front view of wire harness connector

(to Headlight Relay [H-LP RH])

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

Relay terminal 1 - Body ground

Power switch off

11 to 14 V

Relay terminal 5 - Body ground

Power switch off

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

9.

CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP RH RELAY] - HEADLIGHT ECU SUB-ASSEMBLY RH AND MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU])

(a) Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.

(b) Disconnect the A20 headlight ECU sub-assembly RH connector.

(c) Disconnect the I48 main body ECU (multiplex network body ECU) connector.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Relay terminal 3 - A20-13 (ECUB)

Always

Below 1 Ω

Relay terminal 2 - I48-1 (DIM)

Always

Below 1 Ω

Relay terminal 3 or A20-13 (ECUB) - Body ground

Always

10 kΩ or higher

Relay terminal 2 or I48-1 (DIM) - Body ground

Always

10 kΩ or higher

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

READ NEXT:

 Cornering Light Circuit

DESCRIPTION The illumination of the fog light assembly (cornering light) is controlled by the headlight ECU sub-assembly. WIRING DIAGRAM CAUTION / NOTICE / HINT NOTICE: The light system (for Tripl

 Rear Combination Light Assembly

 Precaution

PRECAUTION NOTICE: When disassembling the rear combination light assembly, use static electricity countermeasures SST (desktop antistatic mat set) and observe all precautions to prevent damage to the

SEE MORE:

 Diagnosis System

DIAGNOSIS SYSTEM DIAGNOSIS MODE FUNCTION (a) w/ Lane Centering Function: When a malfunction occurs in the lane tracing assist system system, the LTA indicator light illuminates yellow and a message is displayed on the multi-information display. Warning Message Details DTC/RoB LTA Indicator

 Vehicle Speed Sensor (C1A45)

DESCRIPTION The blind spot monitor sensor receives vehicle speed signals from the skid control ECU via CAN communication. DTC No. Detection Item DTC Detection Condition Trouble Area Note C1A45 Vehicle Speed Sensor A fail flag is transmitted from the skid control ECU. Electron

© 2016-2024 Copyright www.lexunx.com