Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Telematics Transceiver Disconnected (B15DB)

DESCRIPTION

If the radio receiver assembly cannot detect the DCM (telematics transceiver) 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 DCM (telematics transceiver) recognition information (registered information), this DTC will be stored.

The telematics 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 telematics system will not operate normally.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B15DB	Telematics Transceiver Disconnected	DCM (telematics transceiver) disconnected	Harness or connector DCM (telematics transceiver) DCM (telematics transceiver) power source circuit Radio receiver assembly Navigation ECU

HINT:

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

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1.

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

2.	CHECK HARNESS AND CONNECTOR (DCM (TELEMATICS TRANSCEIVER) POWER SOURCE)

(a) Disconnect the J157 DCM (telematics transceiver) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J157-20 (E) - 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
J157-1 (+B) - J157-20 (E)	Always	11 to 14 V
J157-19 (IG2) - J157-20 (E)	Engine switch on (IG)	11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.	CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - DCM (TELEMATICS TRANSCEIVER))

(a) Disconnect the J149 radio receiver assembly connector.

(b) Disconnect the J157 DCM (telematics transceiver) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J149-10 (USBV) - J157-15 (USBV)	Always	Below 1 Ω
J149-11 (USBG) - J157-31 (USBG)	Always	Below 1 Ω
J149-10 (USBV) or J157-15 (USBV) - Body ground	Always	10 kΩ or higher
J149-11 (USBG) or J157-31 (USBG) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.	INSPECT RADIO RECEIVER ASSEMBLY

(a) Disconnect the J149 radio receiver assembly connector.

(b) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition J149-11 (USBG) - Body ground Always Below 1 Ω

*a Component without harness connected (Radio Receiver Assembly)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
J149-10 (USBV) - J149-11 (USBG)	Engine switch on (ACC)	4.75 to 5.25 V

NG

REPLACE RADIO RECEIVER ASSEMBLY

OK

5.	CHECK HARNESS AND CONNECTOR (DCM (TELEMATICS TRANSCEIVER) - NAVIGATION ECU)

(a) Disconnect the J168 DCM (telematics transceiver) connector.

(b) Disconnect the J164 navigation ECU connector.

(c) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition J168-2 (USB+) - J164-1 (USB+) Always Below 1 Ω J168-1 (USB-) - J164-2 (USB-) Always Below 1 Ω J168-3 (USBS) - J164-3 (USBS) Always Below 1 Ω J168-2 (USB+) or J164-1 (USB+) - Body ground Always 10 kΩ or higher J168-1 (USB-) or J164-2 (USB-) - Body ground Always 10 kΩ or higher J168-3 (USBS) or J164-3 (USBS) - Body ground Always 10 kΩ or higher

*a Front view of wire harness connector (to DCM (telematics transceiver)) *b Front view of wire harness connector (to Navigation ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.	CHECK DCM (TELEMATICS TRANSCEIVER)

(a) Replace the DCM (telematics transceiver) with a new one.

Click here

(b) Clear the DTCs.

Body Electrical > Navigation System > Clear DTCs

(c) Turn the engine switch off.

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

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

Body Electrical > Navigation System > Trouble Codes

OK:

No DTCs are output.

OK

END

NG

7.	CHECK NAVIGATION ECU

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

Click here

(b) Clear the DTCs.

Body Electrical > Navigation System > Clear DTCs

(c) Turn the engine switch off.

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

(e) 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