2018 Lexus LS500 & LS500h LED Headlight Module: Decoding Failures and Part Numbers
This guide clarifies the correct part numbers for your LS500's headlight modules, explains failure symptoms like partial DRL lighting, and details replacement costs.
- This module ONLY controls headlights; it is NOT related to TPMS or keyless entry (e.g., part 897B0-50010 is a TPMS receiver).
- You MUST match the part number from your original module exactly, as different versions exist based on vehicle options.
- A common failure symptom is a partially lit Daytime Running Light (DRL), which points to a faulty module.
- Replacement requires removing the front bumper and headlight assembly, and the new module may need dealer programming to function correctly.
A Critical Clarification: This is NOT the TPMS or Keyless Entry Module
Before diagnosing any issue, it's crucial to understand what this part is—and what it isn't. Some databases incorrectly group multiple electronic modules under one umbrella. The LED Headlight Control Module's only job is to operate the headlights. It has no connection to the Tire Pressure Monitoring System (TPMS) or the keyless entry system.
Warning: Several unrelated part numbers are sometimes confused with the headlight module. If you are troubleshooting TPMS or keyless entry, you are looking for a different part. For example, part number 897B0-50010 is the TPMS Receiver, not a headlight module. Other parts like the Stereo Equalizer (86240-50031), Navigation Computer (86840-50131), and Telematics Module (86740-50230) are also separate components.
Symptoms of a Failing Headlight Module
When a headlight control module begins to fail, it can cause a range of issues from partial failure to a completely dark headlight. Here are the most common symptoms:
- Partial DRL or Headlight Failure: One of the most specific known issues for the 2018 LS500 is the partial failure of the Daytime Running Light. Owners have reported that a section of the signature 'L' shaped DRL will go dark while the rest of the headlight functions normally. This can be caused by a failing component, like a diode, within the control module.
- Headlight Not Working at All: The most obvious symptom is a complete failure of one headlight assembly (low beam, high beam, and DRL) to turn on.
- Flickering or Intermittent Operation: The headlight may flicker, blink, or turn on and off randomly while driving.
- Automatic High Beams Malfunction: The auto high-beam feature may stop working, fail to dim for oncoming traffic, or not activate in dark conditions.
- Headlight-Related Dashboard Warnings: A failure may trigger a "Check Headlight System" message or a specific warning icon on the instrument cluster.
Known Issues, Recalls, and TSBs
As of mid-2024, there are no specific recalls for the LED headlight control modules on the 2018 Lexus LS500 or LS500h. However, several recalls were issued for other vehicle systems, including a notable one for a fuel pump that could cause the vehicle to stall. Always check your vehicle's VIN on the NHTSA website or with a Lexus dealer for any open recalls.
A Technical Service Bulletin (TSB), L-SB-0003-19 Rev, was issued for a condition where the rear combination lamp corner could expand, but this does not apply to the front headlights. No TSBs directly addressing headlight module failure were found in public databases.
Pro Tip: If you experience a sudden array of multiple, seemingly unrelated warning lights (e.g., Check Engine, Parking Brake Malfunction, Traction Control Off), the issue may be a weak or failing 12V battery, not the individual modules themselves. This is a common occurrence in modern cars, especially after the vehicle has been parked for an extended period.
Buying a Used LED Headlight Control Module
When purchasing a used module, careful verification is essential to ensure you get the right part and avoid installation problems. This is the most critical step for a successful repair.
1. Verify the Part Number
The single most important rule is to match the part number exactly. The 2018 LS500 and LS500h were built with different headlight systems depending on options like the pre-collision system or adaptive headlamps. Using the wrong module can result in it not working at all. You must physically inspect your vehicle's original module and find the part number printed on its label. Do not rely on a generic online catalog alone.
| Known OEM Headlight Module Part Numbers | Notes |
|---|---|
| 89907-50010 | Left Headlight Control Module / Ballast |
| 89908-50010 | Headlight Control Module |
| 81016-50D40 | Headlamp Computer Sub-Assembly |
| 81016-50C20 | Right Headlight Control Module (for non-adaptive headlamps) |
| 35500-70997 | LED Light Control Module (made by Koito) |
2. Physical Inspection
When your used part arrives, inspect it carefully before installation. Look for:
- No signs of water intrusion: The module casing should be clean and free of water spots or corrosion.
- Clean connector pins: The electrical pins should be straight and shiny, with no green or white corrosion.
- Intact casing: Ensure there are no cracks or damage to the plastic housing or mounting points.
For a complex electronic part like this, a used OEM module is often a more reliable choice than a new, unproven aftermarket part. Used OEM modules were built to Lexus's original quality standards and are guaranteed to have the correct software and functionality, provided the part number matches.
Programming and Installation
The LED headlight control module is typically located on the bottom or back of the headlight assembly itself. To access it, the front bumper cover and the entire headlight housing must be removed from the vehicle.
Programming May Be Required: Some sources indicate that a replacement module may need to be programmed or initialized to the vehicle using dealership-level diagnostic software like Toyota Techstream. This is to ensure the vehicle recognizes the new module and that all advanced features, like auto-leveling or adaptive lighting, function correctly. While some may function as plug-and-play, you should be prepared for the possibility that a visit to a dealer or a qualified independent shop with Lexus-specific tools will be necessary to complete the repair.
Cost of Replacement
Replacing a headlight control module on the LS500 involves significant labor due to the need to remove the front bumper.
| Part / Service | Estimated Cost | Notes |
|---|---|---|
| New OEM Module | $450 - $900 | Price varies significantly by specific part number and dealer. |
| Used OEM Module | $150 - $400 | A common price range on sites like eBay. |
| Shop Labor | $250 - $450 | Estimated 2-3 hours of labor for bumper and headlight removal/reinstallation. |
| Total (with Used Part) | $400 - $850 | This is the most common scenario for out-of-warranty repairs. |
Frequently Asked Questions
Do I need to program a replacement headlight module for my 2018 LS500?
Possibly, yes. While it may function on a basic level, full compatibility and operation of all features may require programming with Toyota's Techstream software. It is best to assume this step may be necessary.
Where is the headlight control module located?
It is bolted directly to the headlight assembly. Access requires removing the front bumper cover and then removing the entire headlight unit from the car.
Can I just replace the module or do I need a whole new headlight?
If the problem is diagnosed to be the module, you can replace just the module. This is much more cost-effective than replacing the entire headlight assembly, which can cost thousands of dollars.
Why is only half of my daytime running light working?
This is a known failure symptom for the 2018 LS500. It is most often caused by a fault within the LED headlight control module, not the LED light strip itself. Replacing the module is the correct repair.
Is the headlight module the same as the TPMS receiver (part 897B0-50010)?
No. They are completely different parts with different functions. The headlight module controls the lights, while the TPMS receiver monitors tire pressure. They are not interchangeable.
Technical Specifications
OEM Part Numbers: 89907-50010 89908-50010 81016-50D40 81016-50C20 35500-70997
Controls full LED headlamp assembly, including low beam, high beam, DRL, and automatic high-beam functions. Operates on the vehicle's 12V system.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Lexus LS500:
- Lexus LS500h:
- 🛍️ Shop This Part
- A Critical Clarification: This is NOT the TPMS or Keyless Entry Module
- Symptoms of a Failing Headlight Module
- Known Issues, Recalls, and TSBs
- Buying a Used LED Headlight Control Module
- 1. Verify the Part Number
- 2. Physical Inspection
- Programming and Installation
- Cost of Replacement
- Frequently Asked Questions
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