Section 362 (Headlight Beam Level Control System): Inspection

WARNING: This page is about a different car, the 2004 Lexus GS 430 and 2004 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT HEADLIGHT BEAM LEVEL CONTROL ACTUATOR RESISTANCE

Check that continuity exists between terminals 2 and 5.
Check that resistance exists between terminals, as shown in the chart.

TERMINAL SPECIFICATIONS

Terminal	Resistance (Ω)
2 - 1	26 - 30
2 - 3	26 - 30
2 - 4	26 - 30
2 - 6	26 - 30
5 - 1	26 - 30
5 - 3	26 - 30
5 - 4	26 - 30
5 - 6	26 - 30

If resistance value is not as specified, replace the actuator.

Fig 1: Inspecting Headlight Beam Level Control Actuator Resistance

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT FRONT HEIGHT CONTROL SENSOR

Connect 3 dry batteries of 1.5 V in series.
Connect terminal 1 to the batteries' positive (+) terminal, and terminal 4 to the batteries' negative (-) terminal, then apply voltage about 4.5 V between terminals 1 and 4.
Measure the voltage between terminals 2 and 4, when the height control sensor link is slowly moved up and down.

VOLTAGE SPECIFICATION

Sensor Link Position	Voltage
Max. HI	Approx. 4.05 V
N	Approx. 2.25 V
Min. LO	Approx. 0.45 V

If voltage is not as specified, replace the height control sensor.

Fig 2: Measuring Voltage Between Terminals 2 And 4

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT REAR HEIGHT CONTROL SENSOR

Connect 3 dry batteries of 1.5 V in series.
Connect terminal 3 to the batteries' positive (+) terminal, and terminal 1 to the batteries' negative (-) terminal, then apply voltage about 4.5 V between terminals 1 and 3.
Measure the voltage between terminals 1 and 2, when the height control sensor link is slowly moved up and down.

VOLTAGE SPECIFICATION

Sensor Link Position	Voltage
Max. HI	Approx. 4.05 V
N	Approx. 2.25 V
Min. LO	Approx. 0.45 V

If voltage is not as specified, replace the height control sensor.

Fig 3: Measuring Voltage Between Terminals 1 And 2

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Connector disconnected:

INSPECT HEADLIGHT BEAM LEVEL CONTROL ECU CIRCUIT

Disconnect the connector from the ECU and inspect the connector on the wire harness side, as shown.

Fig 4: Inspecting Connector On Wire Harness Side

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TESTER CONNECTION SPECIFICATION

Tester connection	Condition	Specified condition
A1 - A5	Ignition switch OFF	26 - 30 Ω
A1 - A6	Ignition switch OFF	26 - 30 Ω
A1 -A7	Ignition switch OFF	26 - 30 Ω
A1 -A8	Ignition switch OFF	26 - 30 Ω
A4 - B4	Ignition switch ON and light control switch HEAD	Below 1.5 V
B1 - B3	Ignition switch OFF	3.5 - 6.5 kΩ
B5-B7	Ignition switch OFF	3.5 - 6.5 kΩ
A4 - Ground	Ignition switch OFF	Continuity

If circuit is not as specified, perform the inspection on the following pages.

Connector connected:

INSPECT HEADLIGHT BEAM LEVEL CONTROL ECU CIRCUIT

Connect the connector from the ECU and inspect the connector, as shown in the table.

Fig 5: Inspecting Connector

TESTER CONNECTION SPECIFICATION

Tester connection	Condition	Specified condition
A1 - A4	Ignition switch ON	Battery positive voltage
A1 - A5	Ignition switch ON, when stopping and bouncing the vehicle.	Pulse generation
A1 - A6	Ignition switch ON, when stopping and bouncing the vehicle.	Pulse generation
A1 - A7	Ignition switch ON, when stopping and bouncing the vehicle.	Pulse generation
A1 - A8	Ignition switch ON, when stopping and bouncing the vehicle.	Pulse generation
B2 - B3	Ignition switch ON	Approx. 2.5 V
B6 - B7	Ignition switch ON	Approx. 2.5 V
B1 - B3 B5 - B7	Ignition switch ON	5 V

If the circuit is not as specified, replace the ECU.

Reference INSPECTION USING OSCILLOSCOPE

HINT:

The correct waveform is as shown in the illustration.

Fig 6: Identifying Correct Waveform