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HOW TO TEST RELAYS (How to repair Relays)

WHAT IS A RELAY

4 pin relayA basic automotive relay is a switch operated by an electromagnet, this is controlled by either a small switch (headlight switch etc.) or a control module/ECU (fuel pump etc.) .This takes the load off the switch etc. and only small wires are required behind the dashboard. If you look at the diagram you will see that the relay connects pin 30 and 87 together. So for a quick test, just bridge them together with a fused wire see picture. If you want to test further connect a meter between 85 and 86 you should see battery voltage when you operate that circuit (note fuel pump relays only work for a few seconds to prime or when cranking).

TESTING  VEHICLE RELAYS

relay testing

HOW TO REPAIR RELAYS

CLICK HERE FOR HOW TO REPAIR RELAYS

 

RELAY PIN TERMINAL NUMBERING


car relay

Many automotive relays now have continental markings and diagram on side to help with pin identification.

1 = 15 or 86       CLICK FOR FULL LIST
2 = 85
3 = 30
4 = 87A
5 = 87

To bridge this relay you would connect 3 and 5

 

 

 

MORE RELAY TYPES

5 pin relay dual output5 pin  relay change over

 These are 5 pin relays the left one is dual output and the right one is a change over.


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