Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: UART Communication Between ANC and Audio Amplifier Missing Message (B1AA187)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Audio, Visual, Telematics / Audio / Video / Active Noise Control System / UART Communication Between ANC and Audio Amplifier Missing Message (B1AA187)

DESCRIPTION

This DTC is stored when an UART communication error occurs between the stereo component equalizer assembly and stereo component amplifier assembly.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1AA187

UART Communication Between ANC and Audio Amplifier Missing Message

Stereo component equalizer assembly detects a UART communication malfunction in stereo component amplifier assembly for 4 seconds or more continuously*
  • Harness or connector
  • Stereo component amplifier assembly
  • Stereo component equalizer assembly

HINT:

*: Malfunction monitoring is not performed under the following conditions, in order to prevent erroneous detection.

  • After engine switch is turned on (ACC) for 3 seconds or more.
  • After the battery voltage returns to normal for 3 seconds.
  • Before 3 seconds have elapsed after battery voltage has returned to normal.

WIRING DIAGRAM

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Active Noise Control > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Active Noise Control > Trouble Codes

OK:

DTC B1AA187 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK HARNESS AND CONNECTOR (STEREO COMPONENT EQUALIZER ASSEMBLY - STEREO COMPONENT AMPLIFIER ASSEMBLY)

(a) Disconnect the G68 stereo component equalizer assembly connector.

(b) Disconnect the G69 stereo component amplifier assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G68-2 (ACK1) - G69-2 (ACK1)

Always

Below 1 Ω

G68-16 (ACK2) - G69-10 (ACK2)

Always

Below 1 Ω

G68-2 (ACK1) or G69-2 (ACK1) - Body ground

Always

10 kΩ or higher

G68-16 (ACK2) or G69-10 (ACK2) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

REPLACE STEREO COMPONENT EQUALIZER ASSEMBLY

(a) Replace the stereo component amplifier assembly with a new or known good one.

Click here

NEXT

5.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Active Noise Control > Clear DTCs
NEXT

6.

CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Active Noise Control > Trouble Codes

OK:

DTC B1AA187 is not output.

OK

END (STEREO COMPONENT AMPLIFIER ASSEMBLY IS DEFECTIVE)
NG

REPLACE STEREO COMPONENT EQUALIZER ASSEMBLY

    ANC ECU EEPROM Data Memory Failure (B1AA044)

    Front Left Microphone Circuit Component Internal Failure (B1AA296,B1AA31C)

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