Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Understanding SAE J2261-2016: Stop Lamps and Turn Signal Lamps for Vehicles 2032 mm or More in Overall Width
SAE J2261-2016 provides standardized test procedures, performance requirements, and guidelines for stop lamps and turn signal lamps intended for use on motor vehicles with an overall width of 2032 mm or more. While designed for large vehicles, the standard also applies to those under 2032 mm width. It ensures that signal lighting meets critical photometric, environmental, and durability criteria to support safety and regulatory compliance.
🛠️ Scope and Applicability
This standard covers stop lamps (S2) and front- and rear-turn signal lamps (I6 or I7) for vehicles with an overall width of 2032 mm or more. It references test methods from SAE J2139, SAE J576, SAE J578, and SAE J759. The performance requirements include vibration, moisture, dust, corrosion, photometry, and warpage tests for plastic components. Lamps conforming to this standard may also be used on narrower vehicles.
Photometric Performance and Identification Codes
Photometric measurements must be taken at a minimum distance of 3 m from the photometer, with the H-V axis parallel to the vehicle’s longitudinal axis. Testing may be performed in steady-burning mode (for all lamps) or flashing mode for LED devices (1.5 Hz ± 0.5 Hz, pulse width >0.3 s at 95% peak intensity). The zone total photometric requirements from Figures 5, 6, or 7 must be satisfied. The table below summarizes the identification codes defined in the standard.
| Code | Description | Condition |
|---|---|---|
| I6 | Front or rear turn signal lamp | Mounted ≥100 mm from lighted edge of lower beam headlamp (front), or rear-mounted |
| I7 | Front turn signal lamp | Mounted <100 mm from lighted edge of lower beam headlamp |
| S2 | Stop lamp | For vehicles with overall width ≥2032 mm |
When a stop/turn signal lamp is combined with a tail, clearance, or parking lamp, the stop/turn signal’s intensity must be at least three times that of the combined lamp at most test points, and five times at specific points (H-V, H-5L, H-5R, 5U-V).
Test Procedures and Design Insights
The standard requires that all lamps undergo vibration, moisture, dust, corrosion, and warpage tests per SAE J2139. Plastic materials must meet SAE J576 optical requirements. A key design aspect is the definition of effective projected luminous lens area, which excludes transparent lenses, mounting holes, reflex reflectors, and other non-light-emitting features.
Engineering Design Insight: The effective projected luminous lens area is the orthogonal projection of the effective light-emitting surface onto a plane perpendicular to the axis of reference. When calculating this area, exclude transparent lenses, mounting holes, and reflex reflectors to ensure accurate photometric compliance.
⚠️ Common Mistake: When determining the identification code I7 for a front turn signal mounted near a lower beam headlamp, measure the distance from the lighted edge of the headlamp to the optical center of the turn signal. Using the overall lens edge or housing can lead to incorrect code assignment and non-compliance.
For turn signals mounted less than 100 mm from the low beam headlamp, the luminous intensity must be at least 2.5 times the values given in Figure 5. Additionally, double-faced turn signals must limit glare to the driver by only meeting performance requirements from the rear to the left (left-hand lamp) or to the right (right-hand lamp).
🔍 Frequently Asked Questions
What is the effective projected luminous lens area and why is it important?
It is the area of the orthogonal projection of the lamp’s effective light-emitting surface onto a plane perpendicular to the axis of reference. This area is critical for photometric calculations because it defines the portion of the lens that actually directs light to the test pattern. Exclusions include transparent lenses, mounting bosses, and reflex reflectors.
How is the identification code I6 vs I7 determined?
Code I6 applies to a rear-turn signal lamp or a front-turn signal lamp mounted 100 mm or more from the lighted edge of the lower beam headlamp (measured from the optical center). Code I7 applies when that distance is less than 100 mm. This distinction affects photometric requirements—I7 lamps must meet higher intensity thresholds.
What are the intensity ratio requirements when stop/turn signal is combined with a tail lamp?
The stop or turn signal must be at least three times brighter than the tail lamp at most test points, and at least five times brighter at the specific test points H-V, H-5L, H-5R, and 5U-V. If the tail lamp’s maximum intensity is below horizontal within a 1.0-degree radius, the ratio at that point may use the lowest tail lamp intensity in that area.
Can LED devices be tested in flashing mode? What are the parameters?
Yes. For LED devices, testing in flashing mode is allowed with a switching frequency of 1.5 Hz ± 0.5 Hz and a pulse width greater than 0.3 seconds measured at 95% peak light intensity. The reported luminous intensity is the maximum achieved during the flash. Filament lamps must be operated at reference luminous flux during on-time.
