Definition: Electromechanical switches used in vehicles to control high-current circuits with low-current signals.
Common Types
- SPDT (Single Pole Double Throw): Most common (e.g., ISO 280, ISO 169).
- DPDT (Double Pole Double Throw): Controls two circuits simultaneously.
- Mini, Micro, and ISO Relays: Vary by size and current rating.
Pin Configuration (ISO 280)
| Pin | Function |
|---|
| 85 | Coil Input (-) |
| 86 | Coil Input (+) |
| 30 | Common |
| 87 | Normally Open (NO) |
| 87a | Normally Closed (NC) |
Applications
- Headlights, horn, fuel pump, starter, cooling fans.
- Enables ECU or switch to manage high-power loads safely.
Key Parameters
- Coil Voltage: 12V DC (standard), some 24V.
- Switching Current: 30A–40A typical.
- Resistance: Coil ~80–100Ω (12V).
Note: Always check pinout and load requirements. Use diode suppression in inductive loads if needed.