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SAE J68-2019: Testing Requirements for Snowmobile Electromechanical Switching Devices
Scope and Definitions 🛠️
SAE J68-2019 outlines standardized tests and performance requirements for electromechanical switching devices used on snowmobiles as defined in SAE J33. The standard covers the following switch types:
- Headlamp beam switch
- Stop lamp switch
- Accessory switch
- Ignition system switch
- Starter motor switch
- Speed control assurance device (SAE J1222)
The tests ensure reliability under extreme conditions typical of snowmobile operation.
Environmental and Endurance Testing
High-Temperature Test
The device is exposed to 49°C ±3°C for at least 2 hours, unless a higher service temperature is determined per SAE J45 fade and recovery test. After conditioning, the switch must function electrically and mechanically for 10 cycles.
Low-Temperature and Humidity Test
The switch must withstand -40°C ±3°C for 2 hours, then a brief exposure to 21°C and 60–90% humidity for 30 minutes, then back to -40°C. The same device used for the high-temperature test shall be used here (clause 5.1.3).
Endurance Test
The endurance test cycles the switch at rated electrical load at 21°C ±6°C, not exceeding 30 cpm. Travel time must be 0.1–0.5 seconds; dwell time at least 0.4 seconds. The same switch used for temperature tests must be used for endurance (clause 5.1.3).
| Device | Sequence | Minimum Cycles | Special Requirements |
|---|---|---|---|
| Headlamp beam switch | Hi-beam–Lo-beam–Hi-beam | 10,000 | Never maintain headlight circuits open |
| Headlamp switch | Off–on–off | 5,000 | |
| Stop lamp switch | Off–on–off | 50,000 | |
| Accessory switch | Off–on–off | 5,000 | |
| Ignition system switch – Emergency shutoff | On–off–on (single) or On–off–on–off–on (dual) | 10,000 | |
| Ignition system switch – Key switch | On–off–on | 5,000 | May include start switch |
| Speed control assurance – Passive | On–off–on | 10,000 | Per SAE J1222 |
| Speed control assurance – Active | Off–on–off | 300,000 | Electrical load only during last 10,000 cycles |
| Starter motor switch | Off–on–off | 5,000 | Include solenoid if used |
⚠️ Common Mistakes:
- Using different switch samples for high-temp, low-temp, and endurance tests – the standard requires the same sample (clauses 4.1.4, 5.1.3).
- Not measuring the service temperature per SAE J45; if not measured, the minimum 49°C test may be insufficient.
- Exceeding travel time (>0.5s) or dwell time (<0.4s) during endurance cycling.
- Failing to meet power supply dynamic requirements: output voltage deviation must be ≤1.0 V from zero to maximum load.
Voltage Drop Measurement
The voltage drop across the switch must not exceed 2% of applied voltage at rated load after endurance. If wiring is integral, include 76 mm of wire on each side of the switch terminals.
Additional Tests and Compliance
Environmental Tests
The switching device must pass either the water intrusion (moisture) test or the corrosion test per SAE J575. The manufacturer can choose which test to perform.
Vibration Test
Vibration test per SAE J575 is also required. Note: Separate samples may be used for the environmental and vibration tests (see Section 8).
💡 Engineering Design Insight: The standard emphasizes cumulative effects – the same switch must withstand high-temperature, low-temperature/humidity, and endurance cycling. This ensures that the switch’s performance degrades consistently over all stress factors. The 2% voltage drop limit is a key indicator of contact integrity and must be verified after endurance to ensure reliable operation throughout the switch’s life.
Frequently Asked Questions
- What is the required test temperature for the high-temperature test? The standard requires 49°C ±3°C for at least 2 hours, but if the switch experiences a higher service temperature during actual use (measured per SAE J45 fade and recovery test), that higher temperature must be used.
- How many cycles must each switch type endure? Cycle counts vary: headlamp beam switch 10,000, stop lamp switch 50,000, active speed control assurance device 300,000 (with electrical load only during last 10,000), and others as listed in Table 1 above.
- Can separate switch samples be used for corrosion/water intrusion and vibration tests? Yes. Section 8 explicitly allows separate samples for the environmental (water intrusion/corrosion) and vibration tests to expedite testing.
- How is voltage drop measured if wiring is integral? The voltage drop measurement must include 76 mm of wire on each side of the switch terminals, ensuring that wiring resistance is accounted for.
