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.
1991 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Control Units
CONTROL UNITS LOCATION
| Component | Location | ||
|---|---|---|---|
| Electronic Control Unit (ECU): | |||
| ABS | |||
| View of ECU Units | Behind right side of dash. See Figure. | ||
| Location of ECU Units | Behind right side of dash. See Figure. | ||
| A/C System | Behind center of dash. See Figure. | ||
| Anti-Theft | Behind left side of dash. See Figure. | ||
| Coolant Level Warning | Behind left side of dash, left of steering column. See Figure. | ||
| Cruise Control | |||
| View of ECU Units | Behind left side of dash. See Figure. | ||
| Location of ECU Units | Behind left side of dash. See Figure. | ||
| Electric Side Mirrors | Behind right side of dash. See Figure. | ||
| Elec. Modulated Air Suspension | In right rear corner of luggage compartment. See Figure. | ||
| Engine | |||
| View of ECU Units | Behind right side of dash. See Figure. | ||
| View of Electronic Control System | Behind right side of dash. See Figure. | ||
| Location of ECU Units | Behind right side of dash. See Figure. | ||
| Power Seat | Under driver's seat. See Figure. | ||
| Progressive Power Steering | Behind center of dash. See Figure. | ||
| SRS System | |||
| View of ECU Units | Behind center console. See Figure. | ||
| Location of ECU Units | Behind center console. See Figure. | ||
| Shift Lock | On center console, behind shift lever. See Figure. | ||
| TRAC System | |||
| View of ECU Units | Behind right side of dash, integral of ABS ECU. See Figure. | ||
| Location of ECU Units | Behind right side of dash, integral of ABS ECU. See Figure. | ||
| Electronic Control Unit (ECU) Column Tilt & Telescopic Steering | Behind left side of dash, above steering column. See Figure. | ||
| Transmission | |||
| View of ECU Units | Behind right side of dash, integrated with engine ECU. See Figure. | ||
| View of Electronic Control System | Behind right side of dash, integrated with engine ECU. See Figure. | ||
| Location of ECU Units | Behind right side of dash, integrated with engine ECU. See Figure. | ||
| Wireless Door Lock | On left side of luggage compartment. | ||
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.