SAE J592: Sidemarker Lamp Requirements Explained
SAE J592 sets the test procedures, requirements and guidelines for sidemarker lamps on road vehicles less than 2032 mm in overall width. It also covers clearance lamps, identification lamps and combination units, which is why it was issued for decades under the title Clearance, Side Marker, and Identification Lamps.
These lamps do something no other lighting on a vehicle does. Headlights show where a vehicle is going and tail lamps show that it is there. Marker lamps show how big it is, and from which angle you are looking at it, which is the information a driver approaching from the side actually needs.
What Is SAE J592?
SAE J592 is a standard published by SAE International, maintained by its Signaling and Marking Devices Standards Committee. It was first issued in January 1937 and has been revised repeatedly since, most recently as J592_201609 in September 2016.
The scope is narrower than the historical title suggests. The standard applies to road vehicles under 2032 mm, which is 80 inches, in overall width. Vehicles at or above that width fall under SAE J2042 instead. The two documents cover the same device types with different requirements, because a wider vehicle needs more marking to convey its size, and because a wider vehicle is seen from further away before its extent is judged.
J592 specifies performance rather than construction. It tells you how much light a lamp must produce, in which directions, and in which colour. It does not tell you how to build it, which is why an LED marker lamp and a filament one can both comply.
The Four Lamp Types J592 Covers
The four devices are distinct, they carry different requirements, and they are routinely confused with one another in specifications. The difference is what each one tells an observer.
The identification lamp spacing is the detail most often got wrong on a conversion. Three lamps in a row is not sufficient on its own. The centre-to-centre spacing has to fall inside that band, because at distance the group has to read as a deliberate cluster rather than as three separate lamps that happen to be near each other.
Where Each Lamp Goes
Mounting position is part of the requirement, not an installation preference. Each device type has a defined place on the vehicle because its purpose depends on where it sits.
SAE J592 Requirements
The substance of the standard sits in its photometric tables and its test procedure. The summary below covers what a specifier needs to know before selecting a lamp.
| Requirement | What the standard sets |
|---|---|
| Photometric performance | Minimum candela values at defined test points, plus totals for each zone. No individual test point may fall below 60% of the minimum value specified for that point. |
| Test distance | For vehicles under 2032 mm, side marker requirements need only be met at inboard test points 4.57 m from the vehicle, on a vertical plane perpendicular to the longitudinal axis, midway between the front and rear side marker lamps. |
| Colour | Front clearance lamps, front and intermediate side marker lamps and front identification lamps are yellow. Colour itself is defined in SAE J578. |
| Combination lamps | Must conform to both the clearance and the side marker photometric requirements. |
| Identification code | Clearance, side marker and identification lamps may be marked P2. Combination clearance and marker lamps may be marked PC, in accordance with SAE J759. |
| Warpage and durability | Tested per SAE J575, which holds the common test methods shared across the signal lamp standards. |
| Current revision | J592_201609, issued September 2016. The 2016 revision changed the side marker test distance from 4.6 m to 4.57 m for consistency with FMVSS 108 and CMVSS 108, where 15 feet converts to 4.572 m. |
That last row looks like housekeeping and is worth understanding, because it tells you how these standards actually behave. The requirement did not change. The figure was corrected so that the SAE document and the federal standards stop disagreeing at the third decimal place. Most revisions to lighting standards are of this kind rather than a change in performance.
SAE J592 and FMVSS 108
This is the point that catches people out. FMVSS 108, the US federal lighting standard, incorporates SAE standards by reference, and the revision it incorporates is not always the current one. For clearance, side marker and identification lamps it adopted SAE J592e, the 1972 revision.
The practical consequence is that a lamp built to the latest SAE revision does not automatically satisfy the federal standard, and a lamp built to the referenced revision does. On a US programme it is the referenced revision that governs, so establish which document and which revision your specification names before selecting hardware. That question costs nothing at specification stage and is expensive at acceptance.
For how the US, European and SAE frameworks relate more broadly, see DOT vs ECE vs SAE standards explained and US vehicle lighting regulations.
Marker Lighting on Military and Dual-Use Vehicles
Marker lighting matters more on a military vehicle than on a car, not less. A tactical or logistics platform is usually longer, frequently towing, often an irregular shape that gives no clue to its extent in the dark, and regularly operating in a column where the vehicle behind judges distance and offset from marker lamps alone.
Any platform that uses public roads has to be road legal on them, whatever else it is specified against. In practice that means marker lighting has to satisfy the civil requirement and survive military service conditions at the same time: vibration, immersion, temperature extremes and pressure washing, none of which the civil standard contemplates. That combination, rather than the photometrics, is usually what rules out a commercial part.
For side turn signal lamps, which sit in the same place on the vehicle and do a different job, see SAE J914. Our LED side marker lights and combined side marker and turn signal units are built for the dual requirement, alongside the wider LED signal lighting range. Where a platform needs something the catalogue does not cover, our OEM programme builds to specification.
Frequently Asked Questions
Test procedures, requirements and guidelines for sidemarker lamps on road vehicles less than 2032 mm in overall width. It also covers clearance lamps, identification lamps and combination clearance and side marker lamps, which is why it was published for many years as Clearance, Side Marker, and Identification Lamps.
No. Tail lamps, also called rear position lamps, are covered by SAE J585 for vehicles under 2032 mm in overall width. Reflex reflectors are covered by SAE J594. All three are commonly fitted to the same vehicle and sometimes to the same assembly, which is why they are frequently confused, but they are separate documents with separate requirements.
Vehicle width, measured overall. J592 applies below 2032 mm, J2042 at 2032 mm and above. They cover the same device types with different requirements. If you are specifying for a mixed fleet, check the width of each platform rather than assuming one document covers all of them. See our article on SAE J2042.
Front clearance lamps, front and intermediate side marker lamps and front identification lamps are yellow. Colour is defined by SAE J578, the colour specification for electric signal lighting devices, which the signal lamp standards reference rather than each defining colour independently. That is why a lamp can be compliant on photometrics and still fail on colour.
They are lighting identification codes defined in SAE J759. P2 marks a clearance, side marker or identification lamp. PC marks a combination clearance and side marker lamp. If you are inspecting an existing fit and want to know what a lamp was approved as, the code moulded into the lens is the quickest answer.
Not as a military requirement, since vehicles procured under government contract are specified against military standards rather than civil ones. But any platform driven on public roads has to be road legal there, and marker lighting is one of the areas where that applies directly. On dual-use and logistics fleets it is normal to specify lighting that meets the civil standard and the military environmental requirements together.