relay for electric water pump

[MurphysLaw]

okay its been awhile working with relays...but i think this is right:

blue wire on csi pump goes to 87 on relay, 30 on relay to 12V (also with an inline fuse), 86 on the relay is for a ground and then 85 is the trigger (hook that up to the fans or fuel or even IGN). Is this all correct?

Thanks for the help!!!

[Injuneer]

Typical relay circuits....

[MN6WS6]

Murphyslaw, yes, that is correct.

Injuneer, you have WAY too much time on your hands for all that drawing

[Injuneer]

Murphyslaw, yes, that is correct.

Injuneer, you have WAY too much time on your hands for all that drawing

That's not my work.... just something I found on the 'net.... apparently credit belongs to "Craig Ueltzen".

Thanks Craig, wherever you are.

[MurphysLaw]

WOW!! I looked but couldnt find anything worth using to anwswer my own question after posting. But heck yeah thats an awesome drawing where ever the guy is.

MN6WS6: thanks for that comformation! That makes sense to me now when I'm tring to think of putting a switch in the circuit, I'd put a diode on the trigger then run it to the switch, and then the switch running to a 12V supply. Makes complete sense now

BUT...can 85 and 86 on the relay be used for a ground or 12V source? Meaning this, use 85 for the ground and 86 for the trigger (complete opposite of what I said in the first post)?

[AmericanZ28]

As long as there is a positive and negative feed going to 86 and 85, the coil will activate. The coils on those relays are not biased and will activate as long as you have voltage and enough current going through it (around 200mA last time I checked.) I would recomend attaching a light bulb (LED and resistor will work perfect) in parallel at the fuse to notify you if current is flowing through the pump. This way, if the pump should go out, or for some reason the pump isn't working, you will imediately know and you wont over heat the engine. Just make sure you mount the bulb somewhere where you will see it as you're driving. Hope this helps.

[MN6WS6]

The SPDT relay (the one you have) is a great thing for installation. You can wire it just about any way you want and not burn it up. 85 and 86 can be either/or, positive or negative. As long as one is power and one is ground, it will throw it. Also, just remember that 87a is at rest with 30 (which means when 85 or 86 have no juice, 87a and 30 are connected, so if you have 12 volts constant going into 87a or 30, you need to protect the other pin from being able to contact any surrounding metal.

[MurphysLaw]

gotcha! Yeah I've got a relay with 4 prongs and then a buddy of mine has a relay with 5 prongs. Both of our pumps now work. We have them hooked up on the IGN fuse...but I'm going to go back and splice it into the lead wire for that fuse.

we want to hook a switch and led for it as well, but how do you know what size diode you need?

[AmericanZ28]

gotcha! Yeah I've got a relay with 4 prongs and then a buddy of mine has a relay with 5 prongs. Both of our pumps now work. We have them hooked up on the IGN fuse...but I'm going to go back and splice it into the lead wire for that fuse.

we want to hook a switch and led for it as well, but how do you know what size diode you need?

You can use any size LED that you want. The only thing you need to worry about is choosing the right resistor to limit current so that you dont burn up the LED. In a 12V set up, you're looking at using a 680 ohm resistor in series with the L.E.D.. This will feed roughly 18mA of current, which is just about right for most LED's. If you want to be able to manually turn the pump on and off, simply put an on/off switch in between the signal wire, which in your case is the IGN wire, and the pin on the relay. I hope this isn't too confusing. I can draw you a schematic if you'd like!

[MurphysLaw]

cool thanks on the offer on the drawing and the information. I'm really tring to learn this "on my own" but if I cant understand how it hooks up when i draw it out then I would love for you to help me.

It makes sense but whats the DIODE for then? Is the diode only when you hook it up to a 12V source that is always hot?? Taking the diode of the drawing seems to make more sense to me

Let me draw it up and see if I can do this on mine and see where my friend is at on his switch hook up.

[MN6WS6]

What diode? If you're talking about the resistor, that would only be if you're using an LED, because most LED's require around 2 volts or so. If you shoot 12 volts to them, they won't light up, so the resistor brings the voltage down to the operating range for them to operate correctly. If you use a 12 volt LED or a 12 volt bulb for an indicator light, then you don't have to worry about the resistor.

[MurphysLaw]

http://ken.lowrance.com/Projects/CSIWaterPump/

hes got a diode in there and i dont know why???

[MN6WS6]

OK, that setup works two ways. One, anytime you have the ignition on, the water pump is on. If you turn the key off, then the switch can be turned on to keep the pump running for as long as you want after the car is shut off. The reason for the diode is to keep the voltage from the switch from backfeeding into the factory fusebox and "lighting up" circuits that you don't want running. Basically, the diode acts as a firewall, preventing 12 volts from going "up" the ignition wire that you tapped into.

His idea will work, but there are ways to do it with no diode required.

[Kevin - Blown 95 TA]

You can just power the wp relay from a +12V ign source and switch the ground on & off. This works because if you got your fan switches hooked into the factory relays, then you need the ign switch on to run the fans anyway. So if you're in the pits and want to cool things off you switch the ign on and the fans and water pump will work (just don't run you're battery down), but then if you want the pump off, say for programming and such, then you just switch it off. Anyway, that,s how I've had it for the last several years, and it works for me.

[MurphysLaw]

THANK YOU! Man, I guess I just didnt know the exact purpose of a diode. I understand completely now! I think by the time this is all said and done then I just might be able to do some electrical work on my own!!! You have no idea how hopeful you guys have been so far!

Now, one last item of detail...just for sh!ts and giggles. Me and my bud think its okay if you do NOT hook #30 on the relay to the fuse box but instead run it straight to the switch. Is that okay? I promise thats my LAST question....I dont want to be annoying .