Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2008 Lexus IS 350FACTORY OEM SERVICE PROCEDURE
Problem Symptoms Table
POWER WINDOW CONTROL SYSTEM
PROBLEM SYMPTOMS REFERENCE
| Symptom | Suspected area | See |
|---|---|---|
| Power window does not operate with multiplex network master switch operation | 1. ECU-B, ECU-IQ PWR fuse | - |
| 2. Multiplex network master switch circuit (power source) | POWER WINDOW MASTER SWITCH POWER SOURCE CIRCUIT | |
| 3. Power window regulator motor circuit | DRIVER SIDE POWER WINDOW MOTOR CIRCUIT | |
| 4. Multiplex network master switch | - | |
| Front passenger side power window does not operate with multiplex network switch operation | 1. PWR fuse | - |
| 2. Multiplex network switch circuit (power source) | FRONT PASSENGER SIDE POWER WINDOW SWITCH POWER SOURCE CIRCUIT | |
| 3. Power window regulator motor circuit (front passenger side) | FRONT PASSENGER SIDE POWER WINDOW MOTOR CIRCUIT | |
| 4. Multiplex network switch (front passenger side) | - | |
| Rear LH side power window does not operate with multiplex network switch operation | 1. PWR fuse | - |
| 2. Multiplex network switch circuit (power source) | REAR POWER WINDOW SWITCH LH CIRCUIT | |
| 3. Power window regulator motor circuit (rear LH side) | REAR POWER WINDOW MOTOR LH CIRCUIT | |
| 4. Multiplex network switch (rear LH side) | - | |
| Rear RH side power window does not operate with multiplex network switch operation | 1. PWR fuse | - |
| 2. Multiplex network switch circuit (power source) | REAR POWER WINDOW SWITCH RH CIRCUIT | |
| 3. Power window regulator motor circuit (rear RH side) | REAR POWER WINDOW MOTOR RH CIRCUIT | |
| 4. Multiplex network switch (rear RH side) | - | |
| AUTO UP/DOWN function does not operate on driver side | 1. Diagnosis check | DIAGNOSIS SYSTEM |
| 2. Power window regulator motor reset | INITIALIZATION | |
| 3. Multiplex network master switch | - | |
| 4. Wire harness | - | |
| AUTO UP/DOWN function does not operate on any door side except driver side | 1. Diagnosis check | DIAGNOSIS SYSTEM |
| 2. Power window regulator motor reset | INITIALIZATION | |
| 3. Multiplex network master switch | - | |
| 4. Wire harness | - | |
| Remote UP/DOWN function does not operate | 1. DATA LIST/ACTIVE TEST | DATA LIST / ACTIVE TEST |
| 2. Multiplex network master switch | - | |
| 3. Multiplex network body ECU | - | |
| 4. Wire harness | - | |
| Power window can be operated after engine switch is turned off even if operated conditions are not met | 1. Front door courtesy switch | INSPECTION |
| 2. Wire harness | - | |
| AUTO UP operation does not fully close power window (Jam protection function is activated) | 1. Power window regulator motor reset | INITIALIZATION |
| 2. Check & clean glass run | - | |
| 3. Multiplex network master switch | - |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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