Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001GL95
Model Year Start: 2020 Model: GR Corolla Prod Date Range: [01/2019 - 03/2019]
Title: LIGHTING (EXT): LIGHTING SYSTEM (for Gasoline Model without AFS): LO-beam Headlight does not Illuminate; 2020 MY Corolla Corolla Hatchback GR Corolla [01/2019 - 03/2019]

LO-beam Headlight does not Illuminate

DESCRIPTION

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

WIRING DIAGRAM

for LED Type Turn Signal Light

for Bulb Type Turn Signal Light

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.*

    Click here 2020 MY Corolla Corolla Hatchback GR Corolla [01/2019 - 09/2019]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

    • *: w/ Smart Key System

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(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) (for LED Type Turn Signal Light)

B

NG (for LH Side) (for Bulb Type Turn Signal Light)

C

NG (for RH Side) (for LED Type Turn Signal Light)

D

NG (for RH Side) (for Bulb Type Turn Signal Light)

E
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 5

D

GO TO STEP 12

E

GO TO STEP 15

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

REPLACE HEADLIGHT UNIT ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

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

(a) Disconnect the 1B 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

1B-1 - A81-3 (LO)

Always

Below 1 Ω

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

Always

10 kΩ or higher
OK

GO TO STEP 8

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.

INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to Headlight Assembly LH)

(a) Disconnect the A29 headlight assembly LH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A29-2 (LO) - Body ground

Light control switch in head position

11 to 14 V
NG

GO TO STEP 7

OK

6.

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

A29-3 (E) - Body ground

Always

Below 1 Ω
OK

REPLACE HEADLIGHT UNIT ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

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

(a) Disconnect the 1B 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

1B-1 - A29-2 (LO)

Always

Below 1 Ω

1B-1 or A29-2 (LO) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

INSPECT NO. 1 INTEGRATION RELAY

(a) Remove the No. 1 integration relay.

Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL

(b) Inspect the No. 1 integration relay.

Click here 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2022]; POWER DISTRIBUTION: INTEGRATION RELAY: INSPECTION

NG

REPLACE NO. 1 INTEGRATION RELAY

OK

9.

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

1A-5 - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

10.

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

1B-2 - 4B-31

Always

Below 1 Ω

1B-2 or 4B-31 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

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.

Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

(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

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

12.

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 14

OK

13.

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

REPLACE HEADLIGHT UNIT ASSEMBLY RH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

14.

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

(a) Disconnect the 1A 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

1A-12 - A80-3 (LO)

Always

Below 1 Ω

1A-12 or A80-3 (LO) - Body ground

Always

10 kΩ or higher
OK

GO TO STEP 18

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

15.

INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to Headlight Assembly RH)

(a) Disconnect the A27 headlight assembly RH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A27-2 (LO) - Body ground

Light control switch in head position

11 to 14 V
NG

GO TO STEP 17

OK

16.

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

A27-3 (E) - Body ground

Always

Below 1 Ω
OK

REPLACE HEADLIGHT UNIT ASSEMBLY RH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

17.

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

(a) Disconnect the 1A 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

1A-12 - A27-2 (LO)

Always

Below 1 Ω

1A-12 or A27-2 (LO) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

18.

INSPECT NO. 1 INTEGRATION RELAY

(a) Remove the No. 1 integration relay.

Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: INTEGRATION RELAY: REMOVAL

(b) Inspect the No. 1 integration relay.

Click here 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2022]; POWER DISTRIBUTION: INTEGRATION RELAY: INSPECTION

NG

REPLACE NO. 1 INTEGRATION RELAY

OK

19.

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

1B-8 - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

20.

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

1A-11 - I85-12 (HRY2)

Always

Below 1 Ω

1A-11 or I85-12 (HRY2) - Body ground

Always

10 kΩ or higher
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR