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SAE J1395-1991: Turn Signal Lamp Standards for Vehicles Over 2032 mm Wide
SAE J1395-1991 specifies test procedures, performance requirements, and design guidelines for front and rear turn signal lamps intended for motor vehicles with an overall width of 2032 mm or more. While this standard is mandatory for wide vehicles, it may also be applied to narrower vehicles for improved consistency. This article provides a technical overview of the key requirements and common engineering considerations.
Performance and Testing Requirements
The standard applies to turn signal lamps used on vehicles with overall width of 2032 mm or more. It references several other SAE standards for color (J578), plastic materials (J576), lighting identification codes (J759), and general lighting device tests (J2139). Devices must comply with a series of environmental and optical tests. The following table summarizes the minimum photometric intensities at key test points for different lamp functions.
| Test Point | Yellow Front | Red Rear | Yellow Rear |
|---|---|---|---|
| H-V | 250.0 | 100.0 | 84.0 |
| H-5L | 130.0 | 50.0 | 50.0 |
| H-5R | 130.0 | 50.0 | 50.0 |
| 5U-V | 165.0 | 84.0 | 84.0 |
| Zone Total (10U-5L to 5D-20L) | 950.0 | 380.0 | 165.0 |
Note: For complete test point grid, refer to Table 1 in the standard. Maximum luminous intensity must not exceed specified limits over any area larger than 0.5 degree radius. Environmental tests include vibration, moisture, dust, corrosion, and warpage (for plastic components). All tests are to be performed per SAE J2139 with modifications as described in the standard.
Design and Installation Insights
When a turn signal lamp is combined with a tail, clearance, or parking lamp, the turn signal intensity must be at least three times (and five times at four key test points) the intensity of the other lamp. This ratio ensures proper signal conspicuity. 🛠️
Front turn signals mounted less than 100 mm from a low beam headlamp must have intensity at least 2.5 times the standard values. Spacing measurement depends on lamp design: for direct-lens type, measure from the center of the light source; for reflector-based lamps, measure from the centroid of the projected luminous lens area.
⚠️ Common mistake: Forgetting the intensity ratio when combining functions. Always verify turn signal output is sufficiently higher than the other lamp’s output.
For multiple compartment lamps, if the distance between adjacent light sources does not exceed 560 mm (two compartments) or 410 mm (three compartments), they must be photometered together; otherwise each compartment must be tested separately. The lighting identification code “I6” applies to rear turn signals and front signals mounted 100 mm or more from the headlamp. “I7” is for front signals mounted less than 100 mm away.
Design tip: Proper indexing of light sources in combined lamps is critical to maintain photometric performance. Refer to SAE J567 for retention system requirements.
Frequently Asked Questions
1. Does J1395 apply to vehicles narrower than 2032 mm?
The standard is intended for vehicles 2032 mm or more in overall width, but it may be used for smaller vehicles at the manufacturer’s discretion.
2. What is the required intensity ratio when a turn signal is combined with a tail lamp?
The turn signal intensity must be at least three times that of the tail lamp at any test point, and at least five times at H-V, H-5L, H-5R, and 5U-V.
3. How should spacing be measured for a reflector-based front turn signal?
For lamps primarily using a reflector, measure from the geometric centroid of the projected luminous lens area to the closest lighted edge of the low beam headlamp.
4. Can multiple compartment lamps be tested separately?
Yes, but only if the spacing between compartments exceeds 560 mm for two compartments or 410 mm for three. Otherwise, they must be photometered together as a single unit.
This article provides a summary of SAE J1395-1991 requirements. Always consult the latest version of the standard and applicable regulations such as FMVSS 108 for complete compliance.
