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SAE J2068-1999: Combination Turn Signal and Hazard Warning Signal Flasher Test Requirements
This article summarizes the test conditions, procedures, and minimum design requirements for flashers used in turn signal and hazard warning systems as specified in SAE J2068-1999. The standard covers nominal 6 V, 12 V, and 24 V flashers and provides a comprehensive framework for ensuring reliable performance under various operating conditions. 🛠️
Scope and Definitions
SAE J2068-1999 defines the test conditions, procedures, and minimum design requirements for combination flashers that serve both turn signal and hazard warning functions. Flashers are classified by type: normally closed (NC) or normally open (NO), and fixed-load or variable-load. The standard references SAE J590, J759, J823, and J945 for related testing and identification.
A flasher is a device installed in a vehicle lighting system that causes the turn signal lamps to flash when the turn signal switch is activated, and the hazard warning lamps to flash when the hazard switch is activated.
Key Test Procedures and Parameters
Start Time Measurement
The start time definition depends on the flasher type:
- Normally closed (NC): Time to open the circuit after voltage is applied, provided the closed circuit remains closed for a minimum of 0.10 s. If the circuit opens in less than 0.10 s, the flasher is considered normally open for that test.
- Normally open (NO): Time to complete one cycle (close and then open the circuit) after voltage is applied.
Tests are performed with both minimum and maximum ampere design loads for each function, and the start time is recorded for three starts separated by at least 5-minute cooling intervals.
Voltage Drop Measurement
The lowest voltage drop across the flasher is measured between the input and load terminals during the “on” period. The measurement is taken during any three consecutive cycles after the flasher has been operating for at least five but fewer than twenty cycles. For fixed-load flashers, the specific design load is used; for variable-load, the maximum design load is used.
Flash Rate and Percent Current On Time
Flash rate and percent on time are measured after five consecutive cycles and averaged over at least three consecutive cycles at each specified test condition. Flashers must be temperature stabilized before each test. The test conditions for turn signal and hazard warning functions are summarized in the table below.
| Function | Voltage (Nominal 12V system) | Ambient Temperature |
|---|---|---|
| Turn Signal | 12.8 V | 24 °C ± 5 °C |
| 12.0 V | -17 °C ± 3 °C | |
| 15.0 V | -17 °C ± 3 °C | |
| 11.0 V | 50 °C ± 3 °C | |
| 14.0 V | 50 °C ± 3 °C | |
| Hazard Warning | 12.8 V | 24 °C ± 5 °C |
| 11.0 V | -17 °C ± 3 °C | |
| 13.0 V | -17 °C ± 3 °C | |
| 11.0 V | 50 °C ± 3 °C | |
| 13.0 V | 50 °C ± 3 °C |
Note: For 6 V systems, halve the voltages; for 24 V systems, double the voltages.
Extreme Temperature Tests
Flashers are also subjected to ambient temperatures of 63 °C ± 3 °C and -32 °C ± 3 °C, where start time and flash rate are measured within the first minute of energization.
Engineering Design and Compliance Insights
🔍 Key Design Insight: Proper classification of flashers as normally closed or normally open is critical. The 0.10-second threshold in start time measurement distinguishes these types, affecting how start time is recorded. Designers must also ensure flashers are tested under both minimum and maximum design loads for variable-load types, as performance can vary significantly.
⚠️ Common Mistake: Confusing start time definitions between normally closed and normally open flashers can lead to incorrect test results. Additionally, measuring voltage drop only at nominal voltage without considering extreme temperatures may overlook potential failures. Always follow the full test matrix specified in the standard.
Frequently Asked Questions
How is start time defined for normally closed vs. normally open flashers?
For normally closed flashers, start time is the interval to open the circuit after voltage is applied, provided the closed circuit lasts at least 0.10 s. If it opens sooner, the flasher is treated as normally open for that test. For normally open flashers, start time is the time to complete one full cycle (close and then open).
What are the test voltage and temperature conditions for turn signal and hazard warning functions?
The test conditions include combinations of extreme voltages and temperatures to ensure reliability. For turn signals, five conditions are specified (e.g., 12.8 V at 24 °C, 12.0 V at -17 °C, etc.). Hazard warning tests use similar but slightly different voltage levels (e.g., 11.0 V or 13.0 V at -17 °C and 50 °C). Full details are in the table above.
How should voltage drop be measured across the flasher?
Voltage drop should be measured during the “on” period across the flasher’s input and load terminals. The measurement should be the lowest value over any three consecutive cycles after the flasher has stabilized for at least five cycles. For variable-load flashers, the maximum design load must be used.
What are the minimum design requirements for flashers per SAE J2068-1999?
The standard specifies that flashers must be tested under defined conditions for start time, voltage drop, flash rate, and durability. Compliance requires meeting all test criteria at extreme temperatures and voltages. Flashers should also be identified with the SAE J590/J945 code per SAE J759.
By adhering to SAE J2068-1999, manufacturers ensure reliable performance of turn signal and hazard warning flashers in demanding automotive environments. 🔍
