1991-1993 Cadillac DeVille & Fleetwood Headlamp: Fitment Traps & Haze Fixes
Your complete guide to diagnosing, replacing, and buying a used OEM headlamp assembly for the front-wheel-drive DeVille and Fleetwood.
- Compatibility is critical: these parts only fit FWD 1991-93 DeVille and FWD 1991-92 Fleetwood. They DO NOT fit the RWD 1993 Fleetwood.
- The most common failures are physical: lens hazing from UV damage and moisture entry from failed seals.
- When buying used, prioritize a clear, crack-free lens and intact mounting tabs over all else.
- Headlight aiming is mandatory after replacement for safety and legal compliance.
Symptoms of a Failing Headlamp Assembly
A failing headlamp assembly is typically a physical problem, not an electrical one. While a burnt-out bulb is the most common reason for a light to go out, issues with the assembly itself can cause poor performance and safety hazards.
- Dim or Yellow Light Output: Even with new bulbs, the light on the road may seem weak. This is almost always caused by the outer polycarbonate lens becoming hazy, yellowed, and cloudy from years of UV exposure. This oxidation on the surface scatters the light instead of projecting it forward.
- Moisture or Condensation Inside: If you see water droplets, fog, or a persistent haze on the inside of the lens, the seal between the lens and the housing has failed. This moisture can corrode the reflective chrome coating and the bulb's electrical contacts, leading to flickering lights or premature bulb failure.
- Loose or Shaky Beam Pattern: A headlight beam that vibrates or shakes excessively while driving points to broken or loose internal mounting points or, more commonly, broken main mounting tabs where the assembly bolts to the car.
- Physical Damage: Cracks in the lens or housing from impacts or stress can allow water to enter and will cause the vehicle to fail a safety inspection.
Compatibility Warning: This is the single most important detail for this part. These headlamp assemblies fit the front-wheel-drive (FWD) 1991-1993 Cadillac DeVille and the FWD 1991-1992 Cadillac Fleetwood. In 1993, Cadillac introduced a completely new, larger, rear-wheel-drive (RWD) car and named it the Fleetwood, replacing the model previously called the Brougham. These headlamps DO NOT fit the 1993 RWD Fleetwood. Always verify the vehicle's drivetrain before purchasing.
Buying a Used OEM Headlamp Assembly: What to Look For
For a vehicle of this age, a good used Original Equipment Manufacturer (OEM) headlamp is often a better choice than a cheap new aftermarket part. OEM units typically have better optics for a correct beam pattern and are made from higher-quality plastics that fit correctly. Here’s what to inspect:
- Lens Condition: Look for a clear, bright lens. Minor surface haze can often be polished out with a restoration kit. However, avoid lenses with deep yellowing, internal cloudiness, or a network of fine cracks (crazing), as these cannot be repaired and will severely limit light output.
- Mounting Tab Integrity: This is critical. Carefully inspect all plastic mounting tabs and bolt holes. After 30+ years, this plastic becomes brittle and can easily snap. A headlight with a broken tab will not mount securely, causing vibration and improper aim.
- Housing and Seal: Check the back of the housing for any cracks or signs of previous repair (like silicone sealant). Look closely at the seam where the lens meets the black plastic housing. It should be clean and free of gaps, which would indicate a failed seal.
- Reflector Condition: Peer inside the lens at the chrome reflector. It should be bright and shiny. Any dullness, flaking, or brownish water stains indicate long-term moisture damage, which will ruin light performance even if the lens is clear.
- Adjuster Screws: Locate the vertical and horizontal aiming screws. Ensure they are not stripped or seized. On older parts, these can sometimes freeze up, making it impossible to aim the headlight after installation.
Headlamp Assembly Replacement and Aiming
Replacing the headlamp assembly is a straightforward job that is feasible for a DIY mechanic. The process generally involves removing the corner turn signal/marker light assembly to access the headlamp's mounting bolts.
Typically, you will need to remove two Torx screws to slide the corner lamp out, which then exposes the 10mm bolts holding the main headlamp assembly in place. Once unbolted, the entire assembly can be pulled forward and the main electrical connector and bulb sockets can be disconnected.
Pro Tip: Before installing the new assembly, it's a good idea to apply a small amount of dielectric grease to the bulb connectors to prevent corrosion and make future bulb changes easier.
Headlight Aiming After Installation
Aiming your headlights after replacement is not optional—it is a critical safety and legal requirement. Improperly aimed headlights can blind oncoming drivers or fail to illuminate the road ahead.
The basic procedure is as follows:
- Park the car on a level surface, 25 feet away from a flat, vertical wall (like a garage door). Ensure the tires are properly inflated.
- Turn on the low beams. The top of the brightest part of the beam pattern on the wall should be slightly below the height of the center of the headlight lens itself.
- Use the adjuster screws on the back or top of the headlamp assembly to adjust the beam. One screw controls vertical (up/down) aim, and the other controls horizontal (left/right) aim.
Cost Comparison
| Part Type | Estimated Price Range | Notes |
|---|---|---|
| New OEM | $80 - $100 per side | May be discontinued or have limited availability from dealers. |
| New Aftermarket | $45 - $75 per side | Quality and fit can vary significantly. May not have the same durability or beam pattern as OEM. |
| Used OEM | $50 - $125 per side | Best value if found in good condition. Price depends heavily on lens clarity and tab integrity. |
| Shop Labor | $75 - $150 per side | Typically about 0.5 to 1 hour of labor per side, plus the cost of aiming. |
Technical Specifications and Part Numbers
| Specification | Detail |
|---|---|
| Headlight Type | Composite Halogen Assembly |
| Low Beam Bulb | 9006 / HB4 |
| High Beam Bulb | 9005 / HB3 |
| Right / Passenger Side OEM Part No. | 16512676 |
| Left / Driver Side OEM Part No. | 16512675, 16513815, 16513816 |
Frequently Asked Questions (FAQ)
Can I upgrade to LED or HID bulbs in my original headlight housings?
It is strongly discouraged. Halogen headlamp reflectors are specifically designed to focus the light from a halogen filament. LED and HID bulbs have a different size and shape, which results in an uncontrolled, scattered beam pattern. This creates dangerous glare for other drivers and often provides worse actual road illumination, and it may be illegal in your area.
Can I just polish my hazy headlights?
Yes, for surface-level hazing and yellowing, a headlight restoration kit can be very effective as a temporary solution. These kits sand off the oxidized layer and apply a new UV protective coating. However, if the damage is internal or the lens is cracked, the entire assembly must be replaced.
Is the driver side headlamp the same as the passenger side?
No, they are not interchangeable. The mounting points and beam patterns are specific to the left (driver) and right (passenger) sides of the vehicle. You must order the correct side for your needs.
Can I just replace the plastic lens?
No, the lens and the housing are manufactured as a single, permanently bonded unit. If the lens is cracked or severely damaged, the entire headlamp assembly needs to be replaced.
Technical Specifications
OEM Part Numbers: 16512676 16512675 16513816 16506301 16513815
Technology: Composite Halogen. Low Beam Bulb: 9006. High Beam Bulb: 9005.
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.
- Cadillac DeVille: