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SAE J914-2014: A Practical Guide to Side Turn Signal Lamps for Vehicles Under 12 Meters
SAE J914-2014 defines the installation, test, performance, and design requirements for side turn signal lamps on vehicles less than 12 meters in length. The updated revision introduces important changes, including the addition of the E5 side direction indicator for UN Regulation 6 harmonization and removal of the requirement for mirror mounting on rear- and side-facing lamps. This article provides an overview of the four lamp types, key photometric testing requirements, and common engineering considerations.
Understanding the Four Lamp Types: E2, E3, E4, and E5
The standard specifies four distinct lamp types, each with a unique lighting identification code (E2, E3, E4, E5). The table below summarizes their definitions and key characteristics.
| Code | Name | Description | Key Notes |
|---|---|---|---|
| E2 | Side Turn Signal Lamp | A supplemental turn signal lamp mounted on the side of a vehicle, typically near the front. | Minimum peak intensity baseline; maximum brightness 30 cd at any test point. |
| E3 | Rear Facing Side Turn Signal Lamp | Incorporated into a rearward-facing surface; mirror mounting is optional. | Minimum peak intensity is 8× that of E2; visibility does not extend as far outward. |
| E4 | Side Facing Side Turn Signal Lamp | Incorporated into an outboard-facing surface; mirror mounting is optional. | Minimum peak intensity is 5× that of E2; limited rearward visibility. |
| E5 | Side Direction Indicator Lamp | Designed to meet UN Regulation 6, Category 5 requirements. | New in 2014; allows harmonization with global UN regulations. |
All types must conform to the photometric zones defined in Figures 1 through 4 of the standard. Note that side turn signal lamps (E2) are supplemental and should not be confused with the required turn signal lamps covered by SAE J588.
Photometric Testing and LED Requirements
Photometric tests are performed according to SAE J575. For lamps that use LED light sources, the additional procedures of SAE J1889 apply. A key change in the 2014 revision is that the stabilization test point for LED lamps is now H-30L for left-side mounting (and H-30R for right-side mounting), replacing previous mirror-referenced positions. Each lamp type must meet specific zone total luminous intensity requirements, with a maximum intensity of 30 cd at any individual test point. The 2014 revision also updated Figures 2 and 3 so that test point totals equal zone totals, improving clarity.
Engineering Design Insight: The removal of mirror mounting descriptions for E3 and E4 lamps provides greater design flexibility. These lamps can now be located anywhere on the vehicle as long as photometric performance is met. The introduction of the E5 side direction indicator enables manufacturers to use a single design for both SAE and UN markets, simplifying global certification.
💡 UN Regulation 6 Harmonization: The E5 side direction indicator was added to allow vehicle manufacturers to meet both SAE and UN requirements with a single design. Test points and photometric zones are defined in Figure 4 of the standard.
Frequently Asked Questions
- What is the difference between E2 and the turn signal lamps from SAE J588? E2 lamps are supplemental side turn signals; they are not a substitute for the primary turn signals required by SAE J588. Their photometric requirements and mounting differ.
- How do I test LED lamps according to J914? LED testing follows SAE J1889 in addition to SAE J575. The stabilization test point must be H-30L for left-side mounting (or H-30R for right-side), and the standard photometric zones still apply.
- Do E3 or E4 lamps need to be mounted in a mirror? No. The 2014 revision removed that requirement. The lamps can be mounted on any surface (e.g., fender, body panel) as long as they meet the photometric requirements of Figures 2 and 3.
- What is the mounting height requirement? Mounting height is the vertical distance from the road surface to the geometric center of the light-emitting area, measured at curb weight (vehicle without payload).
⚠️ Common Mistake: Confusing E2 with required turn signals from SAE J588. Side turn signal lamps are supplemental and have different photometric requirements. Also ensure that LED lamps are tested with the correct stabilization point (H-30L/R) to avoid non-compliance.
