LED modules used in trucks, trailers and RV products can remain in production for many years.
For an OEM manufacturer, this creates a different set of requirements from developing a completely new LED module. A mature lighting product may already have an established PCB, plastic or metal housing, mounting structure, tooling, electrical specification and assembly process.
In these situations, changing the LED module is not always the objective. Maintaining compatibility with the existing product — while keeping production consistent over time — can be just as important.
NKT has supported heavy-duty and marine LED applications for many years, including LED modules used in truck, trailer and RV products. Based on this experience, several practical considerations repeatedly matter when producing or supporting long-running OEM products.
1. Many Vehicle LED Module Projects Start With an Existing OEM Design
Not every custom LED module project begins with a blank PCB.
For many established truck, trailer and RV products we have supported, the customer already owns the product design. The customer provides the technical information, and our role is to manufacture the LED module according to the approved design.
The information may include:
- PCB drawings
- BOM (Bill of Materials)
- Gerber files
- Physical samples
- Electrical specifications
- Mechanical dimensions and mounting requirements
- Connector information
- Assembly requirements
When complete Gerber files are available, they provide an important starting point for production.
However, older products do not always come with a complete set of usable manufacturing files. In some projects, PCB files have had to be recreated or updated based on the available drawings, samples and customer requirements.
This is an important distinction in OEM LED module manufacturing:
Customization does not always mean redesigning the customer's product.
Sometimes the requirement is to reproduce an existing design accurately and maintain it through continued production.
2. Electrical Testing Should Follow the Customer's Defined Conditions
Truck, trailer and RV electrical systems are often described broadly as “12V systems,” but an OEM production specification should be more precise than that.
For many of the constant-voltage LED modules NKT manufactures for these applications, the customer specifies 12.8V DC as the production test voltage.
Each LED board is powered and tested at the specified 12.8V condition. One of the key electrical checks is whether the module's actual current draw falls within the range defined by the customer.
This matters because two boards that both illuminate normally are not necessarily electrically equivalent.
If the measured current falls outside the customer's specified range, the cause needs to be investigated and corrected before the board is accepted.
In our production experience, two factors that can affect the measured current include:
LED Forward-Voltage Variation
LED forward voltage (Vf) naturally varies within a specified distribution. In a constant-voltage circuit, differences in LED Vf can influence the resulting circuit current.
This does not automatically mean that an LED is defective. What matters at the module level is whether the completed board operates within the customer's specified electrical limits.
Resistor Value
The resistance used in a constant-voltage LED circuit directly affects current. An incorrect resistor value can therefore cause the module current to fall outside the required range.
The practical production sequence is straightforward:
Specified test voltage → Measure module current → Compare with customer specification → Investigate any out-of-range result → Correct the problem → Verify again
Electrical verification is one part of our prototype validation and production support process.
For an established OEM product, maintaining its defined electrical behavior can be more important than changing the circuit simply because newer components are available.
3. Why FR4 Is Common in Low-Power Truck, Trailer and RV LED Modules
PCB material should be selected according to the electrical, mechanical and thermal requirements of the actual module.
In many of the truck, trailer and RV LED modules NKT has manufactured, FR4 PCB is commonly used.
These products are generally relatively low power, so excessive LED module temperature has not typically been a major design issue in the projects discussed here.
At the same time, the circuit architecture may require a double-sided PCB.
Depending on the product, we have worked with designs where:
- Copper circuitry is present on both sides while most components are mounted on one side, or
- Components are mounted on both sides of the PCB.
For these modules, PCB construction is therefore closely related to the existing circuit layout, component arrangement, available space and mechanical integration.
This is why PCB material should not be selected based on a simple rule such as “vehicle LED modules require aluminum PCB.” Higher-power applications may have very different thermal requirements.
For a broader comparison of PCB material choices, see FR4 vs. aluminum PCB for LED modules.
4. Why Some Long-Running Products Still Use Through-Hole LEDs
SMD LEDs are now widely used in new LED module designs, and many newer products NKT supports are designed around SMD components from the beginning.
However, some long-running truck, trailer and RV products still use through-hole LEDs.
Why not simply replace them with SMD LEDs?
Because the LED is only one part of an existing OEM product.
An established LED module may already be integrated with:
- A plastic housing
- A metal housing
- Existing mounting features
- Optical or mechanical interfaces
- Production tooling
- An established assembly process
Changing the LED package can potentially require changes elsewhere in the product. If those changes affect the PCB geometry, LED position or mechanical interface, the customer may also need to modify housings, tooling or other components.
For a product that is already performing as required and remains in production, the cost and disruption of such a redesign may provide little practical benefit.
A newer LED package does not automatically make a redesign worthwhile.
For new product development, SMD LEDs can be considered from the beginning. For an established product, maintaining the existing design may sometimes be the more practical OEM decision.
5. Potting Is Product-Specific, Not Automatic
Vehicle and outdoor applications are frequently associated with moisture and environmental exposure. However, this does not mean that every LED PCB used in a truck, trailer or RV product requires the same protection method.
In NKT's production experience, some modules require potting and others do not.
The requirement is determined by the customer's product design and specification.
This distinction is important because PCB-level potting should not be confused with the environmental rating of the finished product. The complete enclosure, sealing method, connectors, mechanical construction and installation environment all contribute to finished-product protection.
For an OEM manufacturing project, NKT therefore follows the approved product requirement rather than automatically adding potting based only on the application category.
6. Supporting an Existing Vehicle Product Can Involve More Than the LED PCB
One of NKT's long-running OEM relationships illustrates why product continuity can become more complicated than reproducing a circuit board.
Around 2013, one of the customer's previous suppliers ceased operations. A number of established products used in truck, trailer and RV applications were transferred to NKT for continued production.
The customer provided available technical information including:
- Drawings
- BOMs
- Gerber files
- Physical product samples
Some PCB information could be used directly, while some boards required additional drawing work.
But the transition extended beyond the LED PCB.
Certain products also required plastic parts, metal components and existing tooling. For some items, NKT needed to coordinate with the original plastic and metal-part suppliers. Some projects also required delivery of a complete assembly rather than only the LED board.
This created a very practical OEM challenge:
How do you keep an established product in production when part of its original supply chain no longer exists?
7. Existing Tooling Does Not Always Mean Usable Tooling
Transferring old tooling from a previous supplier may sound like the simplest way to continue production.
In practice, that tooling may not be immediately usable.
During the transfer of these long-running products, several conditions were encountered.
Some tooling arrived with missing components. Some molds had originally been used together with mold bases belonging to the previous supplier, so the transferred tooling could not simply be installed and run elsewhere without the original supporting structure.
Other tooling had not been adequately maintained or no longer provided the required accuracy.
As a result, the solution depended on the condition of each tool:
Some tooling could be repaired. Other tooling had to be remade.
This experience illustrates an important point for OEM product transfers: having the original PCB files and BOM does not necessarily mean that the entire product can immediately return to production.
For products involving housings, metal parts or assemblies, tooling condition and supplier continuity may also need to be evaluated.
8. Long Product Lifecycles Change the Meaning of “Better”
Many of the products transferred to NKT during that period have had very long production lifecycles, and a number of them remain in production today.
That experience has influenced how we look at changes to established OEM LED modules.
A component or technology may be newer, but that alone does not make it a better choice for an existing product.
For a mature truck, trailer or RV product, an apparently small LED change can potentially affect:
LED → PCB layout → housing → tooling → assembly → product validation
This is why an established customer drawing or BOM should not be changed casually.
When a product is manufactured according to a customer-controlled design, NKT follows the approved drawing and BOM. If a component becomes unavailable, reaches end-of-life, or another change becomes necessary, the proposed alternative should first be discussed and confirmed with the customer before it is introduced into production.
For long-running OEM products:
Production continuity and controlled change can be more valuable than unnecessary redesign.
9. What Should an OEM Provide for an Existing Vehicle LED Module?
If you need a manufacturing source for an existing truck, trailer or RV LED module, the engineering evaluation can usually begin with the information that is currently available.
Useful inputs include:
- Existing LED PCB or finished-product sample
- PCB drawing
- Gerber files, if available
- BOM
- PCB dimensions
- Mounting-hole locations
- Input or test voltage
- Required operating-current range
- LED specifications
- Connector information
- Plastic or metal housing information
- Potting requirements, if applicable
- Assembly requirements
- Relevant acceptance criteria
Not every legacy product will have a complete set of original files.
A physical sample together with available drawings, electrical requirements and mechanical information can still help determine what additional information is needed before production or redesign is considered.
Supporting Long-Running Truck, Trailer and RV LED Products
Custom LED module manufacturing for vehicle applications is not always about creating a more sophisticated circuit.
For many long-running OEM products, the more important questions are practical:
Can the LED module remain compatible with the existing product?
Can its electrical performance be reproduced consistently?
Can old PCB files, tooling and components still support production?
If something must change, can that change be controlled without unnecessarily affecting the rest of the product?
NKT supports custom and existing LED module projects for OEM manufacturers, including truck, trailer and RV applications.
Whether a project begins with a complete Gerber package or an existing product that needs continued production, the first step is to understand what should remain unchanged and what actually needs to be developed.
Have an existing vehicle LED module, drawing or physical sample?
Request a Quote to discuss the available specifications and production requirements.