CLEARANCE SONAR SYSTEM - No. 1 Clearance Warning Buzzer Circuit

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Clearance Sonar System - No. 1 Clearance Warning Buzzer Circuit. PARK ASSIST / MONITORING. Lexus IS250 IS220d GSE20 ALE20

1.PERFORM ACTIVE TEST BY INTELLIGENT TESTER

Connect the intelligent tester to the DLC3.

Turn the engine switch ON (IG).

Turn the intelligent tester main switch ON.

Turn the clearance sonar main switch ON.

Select the Active Test, use the intelligent tester to generate a control command, and then check that the buzzer operates.

Clearance warning ECU:
Item	Vehicle Condition / Test Details	Diagnostic Note
REAR BUZZER	Rear buzzer (Clearance warning buzzer) / STOP or OPERATE	-

OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.CHECK WIRE HARNESS (NO. 1 CLEARANCE WARNING BUZZER - CLEARANCE WARNING ECU)

Disconnect the Q37 ECU connector.

Disconnect the J39 buzzer connector.

Measure the resistance of the wire harness side connectors.

Standard resistance:
Tester Connection Condition Specified Condition
CBZ (Q37-9) - J39-2 Always Below 1 Ω
CBZ (Q37-9) - Body ground Always 10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.CHECK NO. 1 CLEARANCE WARNING BUZZER (TERMINAL VOLTAGE)

Disconnect the J39 buzzer connector.

Measure the voltage of the connector.

Standard voltage:
Tester Connection Condition Specified Condition
J39-1 - Body ground Engine switch ON (IG) 10 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 CLEARANCE WARNING BUZZER - BATTERY)

OK

4.INSPECT NO. 1 CLEARANCE WARNING BUZZER

Apply battery voltage and check operation of the warning buzzer, as shown in the table.

Measurement Condition	Specified Condition
Battery positive (+) → J39-1 Battery negative (-) → J39-2	Operating sound occurs

The clearance warning buzzer does not sound without battery voltage applied because the buzzer is a separately-excited type.

NG

REPLACE NO. 1 CLEARANCE WARNING BUZZER

OK

REPLACE CLEARANCE WARNING ECU ASSEMBLY

LEXUS IS250, IS220d / GSE20 ALE20

Tester Connection	Condition	Specified Condition
J39-1 - Body ground	Engine switch ON (IG)	10 to 14 V