I'm following the writeup for electric aux ports on rotaryresurrection.com and I notice the relay he uses is a 4 pin relay. I can only find 5 pin relays in town, looking at the wiring harness for the 5 pin relay it has the following wire colors:

Red - Power in/out
Yellow - Power in/out
White - Trigger
Blue - Trigger
Black - Ground

I guess the question is, can I use the 5 pin relay, and if I can, do I use the black ground wire that isn't present on a 4 pin relay or do I just leave it unattached to anything.

 

Some of the higher-end relays will have a small schematic of the internals printed on the side of the relay, so that might tell you everything you need to know.

Otherwise, it sounds like a double-pole relay (2 seperate circuits' contacts can be run that will be energized by the same coil).

 

Heres a representation of the diagram, maybe you can translate this is to easier to follow instructions

Wire colors to terminals are:
85 - White
86 - Black
87 - Yellow
87a - Red
30 - Blue

Just to correct on my first post
It looks like the White and Black are the triggers and Blue is unknown to me.

 

Ok. Pretty standard looking relay. Current flowing between pins 85 & 86 will energize the relay. With the relay not energized, pins 30 & 87a are connected. When the relay is energized with current through 85-86, pin 30 breaks contact with 87a & gets connected to 87.

You can use the relay either as normally open or normally closed, depending on which pin 87 you connect to.

Make sense?

-=Russ=-

 

I think I got it, just to put it in to Aux port perspective though, Pin 85 and 86 go to Aux port solenoid, Pin 87 gets power from car, pin 30 gets power from electric pump, pin 87a remains unused.

Is this right or am I a bit off?

 

Convention is put connect the power (battery or ignition) to pin 30, so that triggering the coil will switch the power between pin 87 and pin 87a, but in this case because 87a is unused your description will still work okay.

Relays are one of the most useful electrical components, but seem to cause a lot of confusion. Understanding them makes life more pleasant Have a read of this, it explains relays very well.

http://www.autoshop101.com/forms/hweb2.pdf

 

Thats excellent, thanks to everyone for their help.

NZvert, that link was excellent.

Thanks to everyone again.