In a message dated 4/17/2001 3:43:30 PM Eastern Daylight Time,
jamesnazarian@netzero.net writes:
> or all of those times someone has asked about wiring a relay or other relay
> related questions, I stumbled across a very good reference for how to wire
> a relay.
>
James,
A good site, with some good info, but a little warning is required. The
relays they show on that site are SPDT relays, sometimes referred to as
"change over" relays. Most relays are not of that type; they are usually a
SPST relay, with only 4 pins - 30, 85, 86, and 87 - no 87a pin. It is very
rare to find a SPDT relay in a local auto parts store.
Other than the lack of the 87a pin, (which is called a "normally closed"
output), the 4 pin relays operate the same.
Unfortunately, many 5 pin relays are not really SPDT relays - the pin marked
87a is often just another 87 pin - ie, when the relay is energized, pin 30 is
connected to BOTH of the 87 pins. In this case, the extra pin should be
marked simply 87, but they are often erroneously marked 87a.
Before installing a new relay, check the wiring diagram printed on the side
to be sure what type relay you really have. If there is no diagram (There
usually is one, but not always), you will need to test the relay to be sure
it's what you thought it was when you bought it.
It's a sorry state of affairs, but it is not at all unusual to get the wrong
relay.
Dan Masters
Alcoa, Tennessee
Triumph TR 250 - TR6 Electrical Maintenance Handbook:
http://members.aol.com/danmas6/
Stuffing a V8 into a small British sports car:
http://members.aol.com/danmas/
British V8 Newsletter:
http://members.aol.com/danmas4/mgv8.htm
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