Lexus RX (RX 350L, RX450h) 2016-2022 Repair Manual: Extension Module Disconnected 2 (B1543)

DESCRIPTION

If the radio receiver assembly cannot detect the navigation ECU for a certain period of time (90 seconds) after the engine switch is turned on (ACC) and the radio receiver assembly confirms that the information is missing by checking past navigation ECU recognition information (registered information), this DTC will be stored.

HINT:

The audio and visual system uses USB communication between devices. If an open, short, short to +B or short to ground occurs in the USB circuit, communication is interrupted and the audio and visual system will not operate normally.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1543

Extension Module Disconnected 2

Navigation ECU disconnected

  • Navigation ECU
  • Radio receiver assembly
  • No. 1 navigation wire
  • Harness or connector

HINT:

This DTC may be stored due to environmental reasons such as electrical noise or interference.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Depending on the parts that are replaced during vehicle inspection or maintenance, performing initialization, registration or calibration may be needed. Refer to Precaution for Audio and Visual System.

    Click here

  • Inspect the fuse for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK COMPASS SCREEN

(a) Turn the engine switch on (ACC) and wait for 60 seconds.

(b) Press the "MAP" switch and check that the compass screen is displayed normally.

Result

Proceed to

Compass screen is displayed normally

A

Compass screen is not displayed normally

B

HINT:

  • This DTC may be stored due to environmental reasons such as electrical noise or interference.
  • Clear past DTCs when the compass screen is displayed normally. (Codes stored due to past environmental factors)
A

USE SIMULATION METHOD TO CHECK

B

2.

CHECK DTC

(a) Clear the DTCs.

Body Electrical > Navigation System > Clear DTCs

(b) Turn the engine switch off.

(c) Turn the engine switch on (IG) and wait for 90 seconds.

(d) Recheck for DTCs and check that no DTCs are output.

Body Electrical > Navigation System > Trouble Codes

OK:

No DTCs are output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK HARNESS AND CONNECTOR (NAVIGATION ECU POWER SOURCE)

(a) Disconnect the J153 navigation ECU connector.

*a

Front view of wire harness connector

(to Navigation ECU)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J153-23 (GND) - Body ground

Always

Below 1 Ω

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

J153-10 (+B) - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK NO. 1 NAVIGATION WIRE (RADIO RECEIVER ASSEMBLY - NAVIGATION ECU)

(a) Disconnect the z31 radio receiver assembly connector.

*a

Front view of wire harness connector

(to Navigation ECU)

*b

Front view of wire harness connector

(to Radio Receiver Assembly)

(b) Disconnect the z32 navigation ECU connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

z31-4 (US4+) - z32-4 (US4+)

Always

Below 1 Ω

z31-5 (US4-) - z32-5 (US4-)

Always

Below 1 Ω

z31-6 (UGD4) - z32-6 (UGD4)

Always

Below 1 Ω

NG

REPLACE NO. 1 NAVIGATION WIRE

OK

5.

REPLACE NAVIGATION ECU

(a) Replace the navigation ECU with a new or known good one.

Click here

NEXT

6.

CHECK DTC

(a) Clear the DTCs.

Body Electrical > Navigation System > Clear DTCs

(b) Turn the engine switch off.

(c) Turn the engine switch on (IG) and wait for 90 seconds.

(d) Recheck for DTCs and check that no DTCs are output.

Body Electrical > Navigation System > Trouble Codes

OK:

No DTCs are output.

OK

END (NAVIGATION ECU IS DEFECTIVE)

NG

REPLACE RADIO RECEIVER ASSEMBLY

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