System Operation Check

WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

Trouble shooting of a automatic headlight and/or lighting system complaint begins with verification of the customer problem. If problem occurs, go to step 3. If problem does not occur, go to next step.
If problem does not occur, review conditions under which problem occurred for customer and try to duplicate those conditions. For example, if the problem occurs on rainy days or during high humidity conditions, sprinkle water onto vehicle and see if malfunction occurs. DO NOT sprinkle water directly into engine compartment or onto electronic components. Visually inspect for signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary.
Inspect the multiplex communication system and confirm that there is no trouble by the basic inspection and DTC check. See PRE-CHECK under SELF-DIAGNOSTIC under MULTIPLEX COMMUNICATION SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.

Determine problem symptom.

For headlight and taillight system without daytime running light (DRL) system, see PROBLEM SYMPTOM INDEX (HEADLIGHT & TAILLIGHT SYSTEM WITHOUT DRL) table.
For headlight and taillight system with daytime running light (DRL) system, see PROBLEM SYMPTOM INDEX (HEADLIGHT & TAILLIGHT SYSTEM WITH DRL) table.
For interior light system, see PROBLEM SYMPTOM INDEX (INTERIOR LIGHTS SYSTEM) table.
For headlight beam level control system, fog light system, back-up light system and stop light system, see PROBLEM SYMPTOM INDEX (OTHER SYSTEMS) table.

PROBLEM SYMPTOM INDEX (HEADLIGHT & TAILLIGHT SYSTEM WITHOUT DRL)

Symptom

Suspected Area ⁽¹⁾

Automatic Light Control System Does Not Operate

⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾⁽⁶⁾⁽⁷⁾

Auto Turn-Off System Does Not Operate When The Driver's Door Is Opened

⁽⁸⁾⁽⁷⁾

Auto Turn-Off System: Headlight & Taillight Do Not Come On

⁽⁷⁾⁽⁵⁾

Auto Turn-Off System: Headlight & Taillight Stay On

⁽⁷⁾⁽⁵⁾

Only One Headlight Comes On

⁽⁹⁾⁽²⁾⁽⁵⁾

LO-Beam Does Not Light (All)

⁽¹⁰⁾⁽²⁾⁽⁵⁾

LO-Beam Does Not Light (One Side)

⁽⁹⁾⁽¹¹⁾⁽⁵⁾

HI-Beam Does Not Light (All)

⁽¹²⁾⁽⁵⁾

HI-Beam Does Not Light (One Side)

⁽⁹⁾⁽¹³⁾⁽⁵⁾

Flash Does Not Light

⁽¹³⁾⁽¹²⁾⁽⁹⁾⁽¹⁴⁾⁽⁵⁾

Headlight Does Not Come On

⁽¹⁰⁾⁽³⁾⁽⁹⁾⁽¹⁴⁾⁽⁵⁾

Headlight Flickers Or Is Dark

⁽⁹⁾⁽¹⁴⁾⁽⁵⁾

Only One Taillight Comes On

⁽⁹⁾⁽⁵⁾

Taillight Does Not Come On (Headlight Is Normal)

⁽¹⁵⁾⁽¹⁶⁾⁽¹⁷⁾⁽³⁾⁽⁵⁾

Taillight Does Not Come On (Headlight Does Not Light)

⁽³⁾⁽⁵⁾

Rear Combination Light Does Not Come On

⁽¹⁷⁾⁽⁵⁾⁽⁹⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the automatic light control sensor. See AUTOMATIC LIGHT CONTROL SENSOR under COMPONENT TESTS and AUTOMATIC LIGHT CONTROL SENSOR CIRCUIT under CIRCUIT TESTS.

⁽³⁾	Check the light control switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽⁴⁾	Check the door courtesy switch. See appropriate door courtesy switch inspection under COMPONENT TESTS .

⁽⁵⁾	Check the wiring harness.

⁽⁶⁾	Check the anti-theft ECU. See ANTI-THEFT SYSTEM article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽⁷⁾	Check the body ECU. See BODY CONTROL SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.

⁽⁸⁾	Check the driver door courtesy switch. See DOOR COURTESY SWITCH (FRONT & REAR) under COMPONENT TESTS.

⁽⁹⁾	Check the bulb. Replace the bulb(s) with ones working normally and judge whether they work normally or not.

⁽¹⁰⁾	Check the headlight control relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹¹⁾	Check the H-LP L-LWR fuse then the H-LP R-LWR fuse located in the engine room No. 1 relay block.

⁽¹²⁾	Check the headlight dimmer switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹³⁾	Check the H-LP L-UPR fuse then the H-LP R-UPR fuse located in the engine room No. 2 relay block.

⁽¹⁴⁾	Check the light control ECU. Replace it with one working normally and judge whether it works normally or not.

⁽¹⁵⁾	Check the TAIL fuse then the GAUGE fuse located in the driver side junction block.

⁽¹⁶⁾	Check the taillight control relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁷⁾	Check the light failure relay.

PROBLEM SYMPTOM INDEX (HEADLIGHT & TAILLIGHT SYSTEM WITH DRL)

Symptom

Suspected Area ⁽¹⁾

Automatic Light Control System Does Not Operate

⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾⁽⁶⁾⁽⁷⁾

Auto Turn-Off System Does Not Operate When The Driver's Door Is Opened

⁽⁸⁾⁽⁷⁾

Auto-Turn Off System: Headlight & Taillight Does Not Come On

⁽⁷⁾⁽⁵⁾

Auto Turn-Off System: Headlight & Taillight Stay On

⁽⁷⁾⁽⁵⁾

Only One Headlight Comes On

⁽⁹⁾⁽¹⁰⁾⁽¹¹⁾⁽¹²⁾⁽⁵⁾⁽¹³⁾

LO-Beam Does Not Light (All)

⁽¹⁴⁾⁽¹²⁾⁽⁵⁾

LO-Beam Does Not Light (One Side)

⁽¹¹⁾⁽¹⁵⁾⁽¹²⁾⁽⁵⁾

HI-Beam Does Not Light (All)

⁽¹⁶⁾⁽¹⁰⁾⁽⁵⁾⁽¹³⁾

HI-Beam Does Not Light (One Side)

⁽¹¹⁾⁽¹⁷⁾⁽⁹⁾⁽⁵⁾

Flash Does Not Light

⁽¹⁶⁾⁽¹⁰⁾⁽⁵⁾⁽¹³⁾

Headlight Does Not Come On

⁽¹⁴⁾⁽¹⁰⁾⁽⁹⁾⁽¹⁶⁾⁽³⁾⁽⁵⁾⁽¹²⁾⁽¹¹⁾⁽¹³⁾

Headlight Does Not Come On With Light Control Switch In HEAD

⁽³⁾⁽¹²⁾⁽⁵⁾

Headlight Does Not Go Out With Light Control Switch In OFF

⁽¹⁴⁾⁽¹²⁾⁽⁵⁾

Headlight Flickers Or Is Dark

⁽¹¹⁾⁽¹²⁾⁽⁵⁾

Taillight Does Not Come On With Light Control Switch In TAIL

⁽¹⁸⁾⁽³⁾⁽⁵⁾

Taillight Does Not Go Out With Light Control Switch In OFF

⁽¹⁸⁾⁽³⁾⁽⁵⁾

Headlight Does not Come On With Engine Running & Light Control Switch In OFF

⁽¹⁹⁾⁽¹⁰⁾⁽⁹⁾⁽²⁰⁾⁽²¹⁾⁽⁵⁾⁽¹³⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the automatic light control sensor. See AUTOMATIC LIGHT CONTROL SENSOR under COMPONENT TESTS and AUTOMATIC LIGHT CONTROL SENSOR CIRCUIT under CIRCUIT TESTS.

⁽³⁾	Check the light control switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽⁴⁾	Check the door courtesy switch. See appropriate door courtesy switch inspection under COMPONENT TESTS .

⁽⁵⁾	Check the wiring harness.

⁽⁶⁾	Check the anti-theft ECU. See ANTI-THEFT SYSTEM article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽⁷⁾	Check the body ECU. See BODY CONTROL SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.

⁽⁸⁾	Check the driver door courtesy switch. See DOOR COURTESY SWITCH (FRONT & REAR) under COMPONENT TESTS.

⁽⁹⁾	Check the daytime running light No. 2 relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁰⁾	Check the daytime running light main relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹¹⁾	Check the bulb. Replace the bulb(s) with ones working normally and judge whether they work normally or not.

⁽¹²⁾	Check the light control ECU. Replace it with one working normally and judge whether it works normally or not.

⁽¹³⁾	Check the combination meter. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.

⁽¹⁴⁾	Check the headlight control relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁵⁾	Check the H-LP L-LWR fuse then the H-LP R-LWR fuse located in the engine room No. 1 relay block.

⁽¹⁶⁾	Check the headlight dimmer switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁷⁾	Check the H-LP L-UPR fuse then the H-LP R-UPR fuse located in the engine room No. 2 relay block.

⁽¹⁸⁾	Check the taillight control relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁹⁾	Check the ECU-B2 fuse located in the passenger side junction block then the GAUGE fuse located in the driver side junction block.

⁽²⁰⁾	Check the generator L terminal. See COMBINATION METER CIRCUIT under CIRCUIT TESTS under INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.

⁽²¹⁾	Check the parking brake switch. See PARKING BRAKE SWITCH under COMPONENT TESTS under INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.

PROBLEM SYMPTOM INDEX (INTERIOR LIGHTS SYSTEM)

Symptom

Suspected Area ⁽¹⁾

All Lights Do Not Come ON

⁽²⁾

Driver Door Courtesy Light Does Not Come ON When Driver's Door Is Opened

⁽³⁾⁽⁴⁾⁽⁵⁾

Passenger Door Courtesy Light Does Not Come ON When Passenger's Door Is Opened

⁽³⁾⁽⁴⁾⁽⁵⁾

Room Light Does Not Come On When Rear Right Or Rear Left Door Is Opened

⁽³⁾⁽⁴⁾⁽⁵⁾⁽⁶⁾

Only One Of The Bulbs Come ON

⁽⁷⁾

Illumination Does Not Fade Out When All Doors Are Closed

⁽⁸⁾⁽⁴⁾⁽⁵⁾

Illumination Does Not Fade Out Immediately When The Ignition Switch Is Turned To ACC Or ON Within 15 Seconds After All The Doors Are Closed

⁽⁹⁾⁽¹⁰⁾⁽⁴⁾⁽⁵⁾

Illumination Does Not Fade Out Immediately When All The Doors Are Locked Within 15 Seconds After They Are Closed

⁽¹¹⁾⁽⁴⁾⁽⁵⁾

Interior Light Does Not Light Up (In Front Personal Light)

⁽⁷⁾⁽¹²⁾⁽⁴⁾

Rear Room Light Does Not Light Up

⁽⁷⁾⁽¹³⁾⁽⁴⁾

Vanity Light Does Not Light Up

⁽⁷⁾⁽¹⁴⁾⁽⁴⁾

Luggage Compartment Light Does Not Light Up

⁽⁷⁾⁽¹⁵⁾⁽⁴⁾

Courtesy Light Does Not Light Up

⁽⁷⁾⁽⁸⁾⁽⁴⁾⁽⁵⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the DOME fuse located in the passenger side junction block.

⁽³⁾	Check the appropriate door courtesy switch (front or rear). See DOOR COURTESY SWITCH (FRONT & REAR) under COMPONENT TESTS.

⁽⁴⁾	Check the wiring harness.

⁽⁵⁾	Check the body ECU. See BODY CONTROL SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.

⁽⁶⁾	Check the room light. See ROOM LIGHT under COMPONENT TESTS.

⁽⁷⁾	Check the bulb.

⁽⁸⁾	Check the appropriate door courtesy switch under COMPONENT TESTS .

⁽⁹⁾	Check the ignition switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁰⁾	Check the RADIO NO. 2 fuse then the GAUGE fuse located in the driver side junction block.

⁽¹¹⁾	Check the door unlock detection switch. See POWER DOOR LOCKS & TRUNK LID article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽¹²⁾	Check the front personal light. See FRONT PERSONAL LIGHT SWITCH under COMPONENT TESTS and FRONT PERSONAL LIGHT SWITCH CIRCUIT under CIRCUIT TESTS.

⁽¹³⁾	Check the rear room light. See REAR ROOM LIGHT SWITCH (WAGON) under COMPONENT TESTS.

⁽¹⁴⁾	Check the vanity light. See VANITY LIGHT under COMPONENT TESTS and VANITY LIGHT CIRCUIT under CIRCUIT TESTS.

⁽¹⁵⁾	Check the luggage compartment door courtesy switch. See DOOR COURTESY SWITCH (LUGGAGE COMPARTMENT) under COMPONENT TESTS and DOOR COURTESY SWITCH (LUGGAGE COMPARTMENT) CIRCUIT under CIRCUIT TESTS.

PROBLEM SYMPTOM INDEX (OTHER SYSTEMS)

Symptom

Suspected Area ⁽¹⁾

Back-Up Light System

Back-Up Light Does Not Light Up

⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾

Back-Up Light Remains Always On

⁽⁶⁾⁽⁴⁾

Only One Light Does Not Light Up

⁽⁵⁾⁽⁴⁾

Fog Light System

Front Fog Light Does Not Light Up With Light Control SW TAIL Or HEAD (LO-Beam Only), Headlight Is Normal

⁽⁵⁾⁽⁷⁾⁽⁸⁾⁽⁹⁾⁽⁴⁾

Only One Light Does Not Light

⁽⁵⁾⁽⁴⁾

Rear Fog Light Does Not Light With Light Control SW HEAD (Headlight Is Normal)

⁽⁵⁾⁽¹⁰⁾⁽¹¹⁾⁽⁴⁾

Rear Fog Light Does Not Light With Light Control SW HEAD (Headlight Does Not Light)

⁽¹²⁾⁽⁴⁾

Only One Light Does Not Light

⁽⁵⁾⁽⁴⁾

Headlight Beam Level Control System ⁽¹³⁾

Beam Axis Is Not Controlled (It Is Not Initialized); Headlight Beam Level Control System Does Not Operate

⁽¹⁴⁾⁽¹⁵⁾⁽¹⁶⁾⁽⁴⁾

Beam Axis Is Not Controlled (It Is Initialized); Headlight Beam Level Control System Does Not Operate

⁽¹⁶⁾⁽⁴⁾

Controlled Angle Of Headlight Is Unusual (Angle Is Controlled)

⁽¹⁶⁾⁽¹⁷⁾⁽⁴⁾

Beam Axis Position Is Not Stable During Driving

⁽¹⁸⁾⁽¹⁷⁾⁽⁴⁾

Stop Light System

Stop Light Does Not Light Up

⁽¹⁹⁾⁽²⁰⁾⁽²¹⁾⁽⁴⁾

Stop Light Always Lights Up

⁽²⁰⁾⁽⁴⁾

Only One Light Always Lights Up

⁽⁴⁾

Only One Light Does Not Light Up

⁽⁵⁾⁽⁴⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the GAUGE fuse located in the driver side junction block.

⁽³⁾	Check the ignition switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽⁴⁾	Check the wiring harness.

⁽⁵⁾	Check the bulb(s).

⁽⁶⁾	Check the park/neutral position switch. See DTC P1780: PARK/NEUTRAL POSITION SWITCH under DIAGNOSTIC TESTS under DIAGNOSIS - A-650E article under AUTOMATIC TRANSMISSION in TRANSAXLE/TRANSMISSION.

⁽⁷⁾	Check the FR FOG fuse located in the passenger side junction block.

⁽⁸⁾	Check the front fog light relay. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽⁹⁾	Check the front fog light switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹⁰⁾	Check the ECU-B2 fuse located in the passenger side junction block.

⁽¹¹⁾	Check the rear fog light switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.

⁽¹²⁾	Inspect the headlight and taillight system.

⁽¹³⁾	High Intensity Discharge (HID) type headlight.

⁽¹⁴⁾	Check the ECU-IG fuse located in the driver side junction block.

⁽¹⁵⁾	Check the headlight beam level control actuator. See HEADLIGHT BEAM LEVEL CONTROL ACTUATOR under COMPONENT TESTS.

⁽¹⁶⁾	Check the headlight beam level control ECU. See HEADLIGHT BEAM LEVEL CONTROL ECU CIRCUIT under CIRCUIT TESTS.

⁽¹⁷⁾	Check the headlights.

⁽¹⁸⁾	Check the anti-lock brake system (ABS). See appropriate ANTI-LOCK article in BRAKES.

⁽¹⁹⁾	Check the STOP fuse located in the driver side junction block.

⁽²⁰⁾	Check the stop light switch. See CRUISE CONTROL article in ACCESSORIES & EQUIPMENT.

⁽²¹⁾	Check the light failure relay.

After problem has been identified and repaired, confirm repairs. After repairs have been completed, confirm that problem has been eliminated. Operate system under same conditions recorded for original complaint. If problem is no longer present, repair has corrected problem. If problem is still present, further diagnosis and repair is required.