| Last Modified: 11-29-2007 | 1.6 J | |
| Service Category: Vehicle Exterior | Section: Lighting (ext) | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000002WKT005X |
| Title: LIGHTING (EXT): LIGHTING SYSTEM: DESCRIPTION (2008 Sequoia) | ||
|
Headlight Signal Circuit |
DESCRIPTION
The main body ECU receives a headlight Lo switch information signal from the light control switch, and illuminates the headlight low beam.
WIRING DIAGRAM
INSPECTION PROCEDURE
PROCEDURE
|
1. |
PERFORM ACTIVE TEST USING TECHSTREAM (HEADLIGHT) |
(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 / Headlight Relay
(e) Check that the headlight (low) turn on/off.
Main Body ECU
|
Tester Display |
Test Part |
Control Range |
Diagnostic Note |
|---|---|---|---|
|
Headlight Relay |
Headlight |
ON or OFF |
- |
OK:
Headlight low beams turn on/off.
|
|
2. |
INSPECT FUSE (HEAD LL, HEAD RL) |
|
(a) Remove the HEAD LL and HEAD RL fuses from the engine room relay block. |
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
HEAD LL fuse |
Always |
Below 1 Ω |
|
HEAD RL fuse |
Always |
Below 1 Ω |
(c) Reinstall the HEAD LL and HEAD RL fuses.
|
|
3. |
INSPECT HEADLIGHT (LOW) BULB |
(a) Temporarily replace the headlight (low) bulb with a new or normally functioning one
.
(b) Check that the headlight (low) turn on.
OK:
Headlight (low) turn on.
|
|
4. |
CHECK HARNESS AND CONNECTOR (HEADLIGHT LOW BULB - HEAD RELAY) |
(a) for LH:
(1) Disconnect the A12 headlight (low) LH connector.
(2) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
A12-2 - Body ground |
Light control switch HEAD, dimmer switch Low |
11 to 14 V |
|
Light control switch HEAD, dimmer switch except Low |
Below 1 V |
(3) Reinstall the headlight (low) LH connector.
(b) for RH:
(1) Disconnect the A13 headlight (low) RH connector.
(2) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
A13-2 - Body ground |
Light control switch HEAD, dimmer switch Low |
11 to 14 V |
|
Light control switch HEAD, dimmer switch except Low |
Below 1 V |
(3) Reinstall the headlight (low) RH connector.
|
|
5. |
INSPECT HEADLIGHT RELAY (HEAD) |
(a) Remove the headlight relay from the engine room relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
3 - 5 |
When battery voltage is not applied to terminals 1 and 2 |
10 kΩ or higher |
|
When battery voltage is applied to terminals 1 and 2 |
Below 1 Ω |
(c) Reinstall the headlight relay.
|
|
6. |
CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - BATTERY) |
(a) Remove the headlight relay from the engine room relay block.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Headlight relay terminal 1 - Body ground |
Always |
11 to 14 V |
|
Headlight relay terminal 3 - Body ground |
Always |
11 to 14 V |
(c) Reinstall the headlight relay.
|
|
7. |
CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - HEADLIGHT LOW BULB) |
|
(a) Remove the headlight relay from the engine room relay block. |
(b) for LH:
(1) Disconnect the A12 headlight (low) LH connector.
(2) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Headlight relay terminal 5 - A12-2 |
Always |
Below 1 Ω |
|
Headlight relay terminal 5 - Body ground |
Always |
10 kΩ or higher |
(3) Reinstall the headlight (low) LH connector.
(c) for RH:
(1) Disconnect the A13 headlight (low) RH connector.
(2) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
Headlight relay terminal 5 - A13-2 |
Always |
Below 1 Ω |
|
Headlight relay terminal 5 - Body ground |
Always |
10 kΩ or higher |
(3) Reinstall the headlight (low) RH connector.
(d) Reinstall the headlight relay.
|
|
8. |
CHECK HEADLIGHT (HEADLIGHT RELAY - MAIN BODY ECU) |
(a) Disconnect the DB main body ECU connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
DB-18 - Body ground |
Always |
11 to 14 V |
(c) Reconnect the main body ECU connector.
|
|
|