Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM100000001H5W3
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: LIGHTING (EXT): LIGHTING SYSTEM (for HV Model): LO-beam Headlight does not Illuminate; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

LO-beam Headlight does not Illuminate

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the low beam headlights.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

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PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Headlight Relay

Low beam headlights

OFF or ON

-

Body Electrical > Main Body > Active Test

Tester Display

Headlight Relay

OK:

Low beam headlights illuminate.

Result

Proceed to

OK

A

NG (for LH Side)

B

NG (for RH Side)

C
A

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C

GO TO STEP 9

B

2.

INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to Headlight Assembly LH)

(a) Disconnect the A81 headlight assembly LH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A81-3 (LO) - Body ground

Light control switch in head position

11 to 14 V
NG

GO TO STEP 4

OK

3.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY LH - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A81-4 (E) - Body ground

Always

Below 1 Ω
OK

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NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - HEADLIGHT ASSEMBLY LH)

(a) Disconnect the 2B No. 1 integration relay connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2B-1 - A81-3 (LO)

Always

Below 1 Ω

2B-1 or A81-3 (LO) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

INSPECT NO. 1 INTEGRATION RELAY

(a) Remove the No. 1 integration relay.

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(b) Inspect the No. 1 integration relay.

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NG

REPLACE NO. 1 INTEGRATION RELAY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL

OK

6.

CHECK HARNESS AND CONNECTOR (POWER SOURCE - NO. 1 INTEGRATION RELAY)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

2A-5 - Body ground

Power switch off

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

7.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 4B instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2B-2 - 4B-31

Always

Below 1 Ω

2B-2 or 4B-31 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

(a) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4B-31 - MB-15 (HRLY)

Always

Below 1 Ω
OK

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NG

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9.

INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to Headlight Assembly RH)

(a) Disconnect the A80 headlight assembly RH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A80-3 (LO) - Body ground

Light control switch in head position

11 to 14 V
NG

GO TO STEP 11

OK

10.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY RH - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A80-4 (E) - Body ground

Always

Below 1 Ω
OK

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NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

11.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - HEADLIGHT ASSEMBLY RH)

(a) Disconnect the 2A No. 1 integration relay connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2A-12 - A80-3 (LO)

Always

Below 1 Ω

2A-12 or A80-3 (LO) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

12.

INSPECT NO. 1 INTEGRATION RELAY

(a) Remove the No. 1 integration relay.

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(b) Inspect the No. 1 integration relay.

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NG

REPLACE NO. 1 INTEGRATION RELAY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL

OK

13.

CHECK HARNESS AND CONNECTOR (POWER SOURCE - NO. 1 INTEGRATION RELAY)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

2B-8 - Body ground

Power switch off

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

14.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the I85 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2A-11 - I85-12 (HRY2)

Always

Below 1 Ω

2A-11 or I85-12 (HRY2) - Body ground

Always

10 kΩ or higher
OK

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NG

REPAIR OR REPLACE HARNESS OR CONNECTOR