Description
PAI FSW-0492 is a normally closed (NC) multi-use pressure switch for Mack heavy-duty trucks, replacing OEM Mack 1MR3583M and 25171211. The switch closes a low-side circuit at the OEM pressure threshold to drive dash warning lamps and buzzers in air-system and engine-oil pressure circuits across the Mack chassis. Black/grey housing, 2.36″ overall length. Made by PAI Industries with a 2-year unlimited-mileage warranty.
Signs You Need a New Pressure Switch
- Dash warning light or buzzer activates intermittently at normal operating pressure
- No warning indication when system pressure actually drops below safe levels
- Visible oil or air leak at the switch body
- Erratic gauge readings or warning activations over bumps and vibration
Specifications
| Manufacturer | PAI Industries |
|---|---|
| Part Number | FSW-0492 |
| Part Type | Pressure Switch (multi-use, air or oil) |
| Switch Position | Normally Closed (NC) |
| Overall Length | 2.36″ |
| Color / Finish | Black / Grey |
| OEM Reference | Mack 1MR3583M / 25171211 |
| Warranty | 2-Year Unlimited Mileage |
Cross References
This pressure switch replaces or is equivalent to the following part numbers:
- Mack: 1MR3583M, 25171211
Applications
Mack multiple-use application — fits a range of Mack truck chassis including:
- Mack R / RD / RB / DM / DMM Series
- Mack CH / CL / CS / CM Series
- Mack CX / CXN Vision Series
- Mack CV / LE / MR Series
This switch is used in multiple air and oil pressure circuits across the Mack catalog. Verify your truck model, switch location, and pressure rating before ordering to confirm fitment.
