1986-1991 Ford Aerostar Headlights: Sealed Beam vs. Composite & Failure Diagnosis

Identifying Your 1986-1991 Aerostar Headlight Type

Before buying a replacement part, you must know which headlight system your Aerostar uses. The two types, sealed beam and composite, are not interchangeable without significant modification. Here’s how to tell them apart:

• Sealed Beam Headlights: These look like a single, solid glass block. The front lens is made of glass and has markings like "H6054" molded into it. When the bulb burns out, you replace the entire rectangular glass unit. These were common on earlier models in this generation.
• Composite Headlights: These have a plastic (polycarbonate) lens that is flush with the front of the vehicle. The bulb is replaced from the back of the housing. These assemblies are typically found on later models, such as 1989-1991, and often on higher trim levels like XLT or Eddie Bauer.

Symptoms of Failure

Headlight problems on the first-generation Aerostar are common, but usually straightforward to diagnose.

• Headlights Shut Off While Driving: One of the most frequently reported issues is the headlights, both high and low beams, turning off and on by themselves. This is almost always caused by the headlight switch on the dashboard or its electrical connector overheating and melting.
• One Headlight Is Out: If a single headlight doesn't work, the cause is typically a burned-out bulb (on composite models) or a failed sealed beam unit.
• Dim or Yellow Headlights: On composite models, the plastic lenses are prone to oxidizing from UV exposure, causing them to become hazy or yellow, which severely restricts light output. On sealed beam models, dimness is just a characteristic of the older technology. Poor electrical grounds can also cause dim lighting on either type.
• Flickering Lights: Flickering is often a sign of a poor electrical connection. This could be a loose ground wire, a corroded bulb socket, or the beginning of a failing headlight switch.
• Moisture Inside the Lens: This only affects composite headlights. If you see condensation or water droplets inside the housing, it means the seal on the back of the assembly has failed, allowing moisture in.

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

While there are no major recalls specifically for the headlights on the 1986-1991 Aerostar, a significant safety recall is worth noting for owners.

• NHTSA Ignition Switch Recall: Ford recalled 1988-1991 Aerostars due to a faulty ignition switch that could short circuit and potentially cause a fire, even when the vehicle was turned off. While unrelated to headlight function, it is a critical safety repair that owners should ensure has been performed.
• Headlight Switch Failure: Though not an official recall, the failure of the headlight switch and its connector is a widely known issue. The high electrical current drawn by the headlights passes directly through the switch, causing it to overheat and melt over time. Inspecting this switch and connector is a primary step in troubleshooting any intermittent headlight problem.

Buying a Used 1986-1991 Aerostar Front Lamp

Buying a used OEM headlight can be a great way to save money, especially if you need to replace a damaged composite housing. Here’s what to look for:

1. Confirm the Type: First and foremost, make sure you are buying the correct type (sealed beam or composite) for your van. They do not swap over easily.
2. Inspect Composite Lenses: For composite headlights, the lens condition is paramount. Look for clear, non-yellowed plastic. Avoid lenses with heavy cloudiness, deep scratches, or internal crazing (spiderweb cracks), as these cannot be easily repaired and will reduce light output.
3. Check All Mounting Tabs: The headlight assemblies are held in by plastic tabs that become brittle with age and can snap off during removal. Carefully inspect all mounting points on the housing to ensure they are intact and free of cracks or previous glue repairs.
4. Examine the Rear Seal and Connector: On composite units, check the rubber seal where the bulb twists in. It should be pliable and intact to prevent moisture entry. For all types, inspect the electrical connector plug for any signs of melting, corrosion, or brittle wires.
5. Look for OEM Markings: Genuine Ford parts will have a Ford logo and part number molded into the housing. OEM parts generally offer better fit and durability than cheap aftermarket alternatives.

Cost Comparison

Prices for replacement headlights can vary significantly. OEM parts are often discontinued, making used OEM and new aftermarket the most common options.

Replacement Overview & Headlight Aiming

Replacing the headlight assembly is a DIY-friendly job that requires basic tools.

1. Remove the Bezel: The trim piece surrounding the headlight (bezel) must be removed first. It is held on by several screws, some of which may be Torx head.
2. Unscrew the Assembly: The headlight unit itself (or the sealed beam bucket) is held to the core support by a few screws (often four).
3. Disconnect Wiring: Unplug the electrical connector from the back of the bulb or sealed beam unit.
4. Installation & Aiming: Installation is the reverse of removal. Crucially, you must aim the headlights after installation. Failure to do so can blind oncoming drivers and is illegal. Aiming is done by parking the van on a level surface about 25 feet from a flat wall. Use the vertical and horizontal adjustment screws on the assembly (accessible with a Phillips screwdriver) to align the brightest part of the beam with the specified height and position outlined in the owner's manual.

Frequently Asked Questions (FAQ)