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Starting at $15.95, AutoBuffy stocks 2 air brake pressure switches from Standard Ignition. This switch monitors air pressure in your brake system and signals the dash warning light or cuts power to critical circuits when pressure drops too low. A failed switch leaves you flying blind on brake system health — a serious safety risk on any air-braked vehicle.
The main decisions are thread size and port configuration, rated activation pressure (PSI set point), and whether the switch is normally open or normally closed. Buying a switch with the wrong PSI rating means your warning system triggers at the wrong threshold — either masking a real problem or creating nuisance alarms. Always confirm the OE pressure rating and electrical connector type before ordering.
| Option | Best for | What you get |
|---|---|---|
| OE-equivalent replacement | Restoring factory warning thresholds and connector fit on a International M800 used in normal service | Matched PSI set point, correct thread pitch, and plug-and-play connector — no adaptation needed |
| Heavy-duty / upgraded switch | International M800 in severe-duty, high-cycle, or extreme-temperature service such as construction or refuse | Reinforced diaphragm, wider temperature rating, and longer service life under constant pressure cycling |
| Normally-open (NO) switch | Warning-light circuits that ground through the switch to illuminate on low pressure | Circuit stays open at normal pressure; closes and triggers the warning when pressure falls below the set point |
| Normally-closed (NC) switch | Power-cut or relay circuits that require the switch to open on low pressure to interrupt a function | Circuit stays closed at normal pressure; opens to cut the signal when pressure drops — common on transmission interlocks |
Before starting, drain the affected air tank to zero pressure and verify with a gauge — never remove a fitting under pressure. Thread the new switch in by hand first to avoid cross-threading, then snug it with a wrench using PTFE tape on the threads; overtightening can crack the switch body. Reconnect the electrical connector, rebuild system pressure, and confirm the warning light extinguishes at the correct pressure threshold before returning the vehicle to service.