I have been wrestling with this one as well. Here's what I decided to do.

I will wire the power to the pump directly from the battery, with a relay to turn it on and a fuse to protect everything. Nothing really out of the ordinary here.

As a verification, I will run wires from each side of the pump to a second relay in the car. When the relay is receiving power, it switches on a green LED (wired to the normally open contact on the relay). When no power is received at the relay, it switches on a red LED (wired to the normally closed contact).

If the motor stops working entirely, usually it will pop the fuse. If the motor overheats, it will be drawing more current than the fuse allows and also blow the fuse.

This way, if the pump is not getting power, the green light turns off and the red light turns on. The warning relay has an audible click to it, but I suppose you could wire in a buzzer of some sort.

BRAD

 

To really get your attention,
you could wire up the system to start up the wipers, honk the horn, flash the head lights, and mute your radio.
I think a loud audible alert would be best, like wiring a horn from an alarm to the system just in case the car is running and you are not in the car to monitor the gauge and the warning lights.

 

Here it is, I found on CSI's site.

http://www.csiperformance.com/cooling_6.html

#1225 $98.88

You could wire it to a bull-horn under your seat O.K. that would be extreem but damn good insurance and because its temp related and adjustable with two settings (watch/warning - light/buzzer - buzzer/bullhorn) it covers any cooling system failure. But where did you get a better price Zepher?

Edit: I didn't see anything about 2 temp settings on their page.

 

I bought it from Jegs about 2 years ago. mine is still pretty much new since my car only ran for 6 weeks and died before I had a chance to hook up the gauge completely.

I need to look at the manual again, but there is an on setting and an off setting, don't remember if the off setting was a preset temp differential from the on setting.

 

I know this is a fairly old post, but as I'm about to install an electric pump this topic interests me. Am I missing something because it appears to me that the pump would always have power using this schematic. As a matter of fact it looks like the only time the pump doesn't have +12v applied is when the relay is energized.

 

A little confusing, but I think the diagram shows the relay in the operated position.

 

Thanks Shoe I thought it was just me. I looked at a relay and 87 is the NO terminal on the relay. So if you wire it using the numbers it would work. But the relay is actually drawn incorrectly and it is confusing. I was taught neg to pos current flow, Navy, I understand some other branches teach hole flow, pos to negative so maybe thats where that came from. But I've never seen a relay drawn like that.