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SAE J1373-2015: Engineering Guidelines for Rear Cornering Lamps (Vehicles <9.1m)
Rear cornering lamps provide supplemental illumination to the side and rearward area when backing up, improving safety for vehicles under 9.1 m overall length. This recommended practice defines test methods, performance criteria, and practical guidelines for design and installation.
Key Requirements & Photometric Specifications
Lamps must emit white light (SAE J578) and may include incidental red, yellow, or white light from adjacent optics, provided non-white components do not exceed 20 % of total luminous intensity at each test point. Plastic optical components must comply with SAE J576. 🛠️ The following table summarizes minimum luminous intensity values at specified test positions:
| Horizontal Angle | Vertical 0° | Vertical 5° Down | Vertical 10° Down | Vertical 20° Down |
|---|---|---|---|---|
| 0° | 80 cd | 40 cd | 20 cd | 10 cd |
| 5° L | 50 cd | 25 cd | 12 cd | 6 cd |
| 10° L | 30 cd | 15 cd | 8 cd | 4 cd |
| 20° L | 15 cd | 8 cd | 4 cd | 2 cd |
| 30° L | 8 cd | 4 cd | 2 cd | 1 cd |
| 45° L | 4 cd | 2 cd | 1 cd | 0.5 cd |
For right‑side mounting, substitute right‑hand angles for left‑hand angles. Photometry is performed with the light source at least 3 m from the photometer, using the H‑V axis perpendicular to the vehicle’s longitudinal axis.
Testing & Engineering Design Insights
Lamps undergo vibration, moisture, dust, corrosion, warpage, and color tests per SAE J575 (with modifications) and SAE J578. A critical design insight: incidental non‑white light must be measured separately at each test point and its sum limited to 20 % of the total light output – a common oversight. Additionally, photometric compliance must be verified using only the white light component. Plastic parts should be selected for temperature and UV stability as required by SAE J576. The light source retention system must meet SAE J567.
⚠️ Common Mistake: Failing to account for incidental light contributions from adjacent lenses or reflectors. Always measure non‑white light at each test point and ensure it stays under 20 % of the total to comply with the standard.
Installation & Mechanization Guidelines
Mount lamps at the rear on each side, near or combined with other lighting functions – each function must independently meet its applicable standard. To maintain performance in harsh conditions, position lamps to minimize dirt, grime, and snow accumulation. The electrical system must supply adequate voltage to ensure rated luminous intensity.
🔍 Mechanization: The rear cornering lamp should illuminate only when the ignition is on and reverse gear is engaged.
Frequently Asked Questions
What color is allowed for rear cornering lamps?
The primary light must be white per SAE J578. Incidental red, yellow, or white light from adjacent optics is permissible as long as the sum of non‑white measurements does not exceed 20 % of the total light output at each specified test point.
What tests are required for compliance?
Lamps must pass vibration, moisture, dust, corrosion, photometry, and warpage tests per SAE J575 (with modifications), plus color testing per SAE J578 and plastic material testing per SAE J576.
When should the rear cornering lamp be activated?
According to the guidelines, the lamp should be on only when the ignition is energized and the vehicle is in reverse gear.
What are the photometric measurement conditions?
Conduct photometric tests at a distance of at least 3 m with the H‑V axis horizontal through the light source and perpendicular to the vehicle’s longitudinal axis. For left‑side lamps, use left‑hand angles; for right‑side, substitute right‑hand angles.
