Useful tips

How does a 4 terminal relay work?

How does a 4 terminal relay work?

4 pin relays use 2 pins (85 & 86) to control the coil and 2 pins (30 & 87) which switch power on a single circuit. A normally open relay will switch power ON for a circuit when the coil is activated. A normally closed relay will switch power OFF for a circuit when the coil is activated.

Are all 4 pin relays the same?

The problem is, not all relays are the same. Many relays, if installed for the wrong application, could and will cause a short (Internal Relay Circuit) and most likely cause functionality issues or even damage to the vehicle computer systems.

How many pins does a four terminal relay have?

The relay will have 4 pins; 2 will connect to the control circuit and 2 will connect to the high power load. Identify the relay as an ISO mini type. The International Standards Organization (ISO) defines this type of relay as 1 inch (2.5 cm) square (25.4 mm square).

What’s the difference between mini relay and 12 volt?

They are rectangular in section and narrower than a mini relay with a slightly different pin layout, and are typically available in ‘make and break’ and ‘changeover’ configurations, with and without suppression diodes. In addition, the terminal numbering is different, using 1, 2, 3, 4 & 5 instead of 30, 85, 86, 87 & 87a.

Which is the terminal on the changeover relay?

Changeover relay. Two circuits (terminals 87 and 87a ) have a common terminal (30). When the relay is at rest 87a is connected to 30, and when the relay is energised 87 becomes connected to 30 (but never both at the same time).

What is the current capacity of a 12 volt relay?

Typically 12V for passenger vehicles and small craft but also available in 6V for older vehicles and 24V for commercial applications (both auto and marine). This is the current carrying capacity of the high current circuit (s) and is normally between 25A and 40A, however it is sometimes shown as a dual rating on changeover relays e.g. 30/40A.