Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Microphone Circuit Open (B157213)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Audio & Visual & Telematics / Cellular Communication / Safety Connect System / Microphone Circuit Open (B157213)

DESCRIPTION

This DTC is stored when the DCM (telematics transceiver) detects a malfunction in the telephone microphone assembly circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B157213

Microphone Circuit Open

Current at terminal MCVD is lower than the malfunction threshold for 10 seconds or more while the engine switch is on (IG)
  • DCM (telematics transceiver)
  • Telephone microphone assembly
  • Harness or connector

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 Safety Connect System.

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PROCEDURE

1.

CHECK DTC

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG) and wait for 10 seconds or more.

(d) Turn the Techstream on.

(e) Clear the DTCs.

Body Electrical > Telematics > Clear DTCs

(f) Check for DTCs and check that no DTCs are output.

Body Electrical > Telematics > Trouble Codes

OK:

No DTCs are output.

OK

USE SIMULATION METHOD TO CHECK

NG

2.

CHECK HARNESS AND CONNECTOR (DCM [TELEMATICS TRANSCEIVER] - TELEPHONE MICROPHONE ASSEMBLY)

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

(b) Disconnect the U15 telephone microphone assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J157-5 (MCVD) - U15-1 (MACC)

Always

Below 1 Ω

J157-6 (MCI+) - U15-2 (MIC+)

Always

Below 1 Ω

J157-7 (MCI-) - U15-4 (MIC-)

Always

Below 1 Ω

J157-23 (SGND) - Body ground

Always

10 kΩ or higher

J157-5 (MCVD) or U15-1 (MACC) - Body ground

Always

10 kΩ or higher

J157-6 (MCI+) or U15-2 (MIC+) - Body ground

Always

10 kΩ or higher

J157-7 (MCI-) or U15-4 (MIC-) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK DCM (TELEMATICS TRANSCEIVER) (TELEPHONE MICROPHONE ASSEMBLY POWER SOURCE)

(a) Remove the telephone microphone assembly but do not disconnect the connectors.

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*a

Component with harness connected

(Telephone Microphone Assembly)

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

U15-1 (MACC) - Body ground

Engine switch on (ACC)

4 to 6 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

U15-4 (MIC-) - Body ground

Always

Below 1 Ω
OK

REPLACE TELEPHONE MICROPHONE ASSEMBLY

NG

4.

REPLACE DCM (TELEMATICS TRANSCEIVER)

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

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NOTICE:

  • The engine switch must be off
  • Do not exchange the DCM (telematics transceiver) with one from another vehicle.
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