Trouble Shooting

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 body control 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. If problem still cannot be created, go to next step.
Inspect the multiplex communication system. See MULTIPLEX COMMUNICATION SYSTEM article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.

Determine the problem symptom. See PROBLEM SYMPTOM INDEX table.

PROBLEM SYMPTOM INDEX

Symptom

Suspected Area ⁽¹⁾

Door Lock Control

Lock Or Unlock Cannot Be Operated With Door Lock Control Switch

⁽²⁾⁽³⁾⁽⁴⁾

Door Key Linked Function Does Not Operate

⁽⁵⁾⁽³⁾⁽⁴⁾

Key Confinement Prevention Function Does Not Operate

⁽⁶⁾⁽³⁾⁽⁴⁾

Light Control

Auto Turn-Off Does Not Operate

⁽⁷⁾⁽⁸⁾⁽⁴⁾⁽⁹⁾

Does Not Operate Illuminated Entry

⁽¹⁰⁾⁽⁹⁾⁽⁴⁾

Warning Lights & Buzzers

Key Reminder System Does Not Operate

⁽⁶⁾⁽⁴⁾

Seat Belt Warning Does Not Operate

⁽¹¹⁾⁽⁴⁾⁽¹²⁾

Wireless Door Lock Control

All Functions Of Wireless Door Lock Control System Do Not Operate

⁽¹³⁾⁽⁶⁾⁽¹⁴⁾⁽⁴⁾

Lock/Unlock Function Does Not Operate

⁽⁵⁾⁽¹⁵⁾⁽⁴⁾

Automatic Lock Function Operates Even If Any Door Is Opened Within 30 Seconds After All Doors Are Unlocked By Wireless Door Lock Control System

⁽¹⁶⁾⁽⁴⁾

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

⁽²⁾	Check the door lock control switch circuit. See DOOR LOCK CONTROL SWITCH CIRCUIT under CIRCUIT TESTS.

⁽³⁾	Check the power window master switch. See POWER WINDOW MASTER SWITCH CIRCUIT under CIRCUIT TESTS.

⁽⁴⁾	Check the body ECU. See PIN VOLTAGE TESTS .

⁽⁵⁾	Check the door key lock and unlock switch circuit. See Figure.

⁽⁶⁾	Check the key unlock warning switch circuit. See KEY UNLOCK WARNING SWITCH CIRCUIT under CIRCUIT TESTS.

⁽⁷⁾	Check the driver side door courtesy switch. See DOOR COURTESY SWITCH CIRCUIT (FRONT & REAR) under CIRCUIT TESTS.

⁽⁸⁾	Check the ignition switch. See IGNITION SWITCH POWER SOURCE CIRCUIT under CIRCUIT TESTS.

⁽⁹⁾	Check the anti-theft ECU. See PIN VOLTAGES under ANTI-THEFT SYSTEM article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽¹⁰⁾	Check the illumination circuit. See ILLUMINATION CIRCUIT under CIRCUIT TESTS.

⁽¹¹⁾	Check the driver buckle switch circuit. See DRIVER BUCKLE SWITCH CIRCUIT under CIRCUIT TESTS.

⁽¹²⁾	Check the combination meter. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.

⁽¹³⁾	Check the wireless door lock transmitter. See REMOTE KEYLESS ENTRY article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽¹⁴⁾	Check the wireless door lock ECU. See REMOTE KEYLESS ENTRY article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT.

⁽¹⁵⁾	Check the door unlock detection switch circuit. See DOOR UNLOCK DETECTION SWITCH CIRCUIT under CIRCUIT TESTS.

⁽¹⁶⁾	Check the door courtesy switch circuit. See DOOR COURTESY SWITCH CIRCUIT (FRONT & REAR) under CIRCUIT TESTS.

Inspect the body control circuits. See CIRCUIT TESTS .
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 and no DTCs are present, repair has corrected problem. If problem is still present or DTCs are reset, further diagnosis and repair is required.