Anyone have a solution for a warning light for an electric water pump. I want to have a light come on if electrical power to the pump is lost. I had that happen one time and the engine gets hot really fast. Fortunately i caught it right away. I figure if it starts to fail mechanically, the temp will go up slower so that's not as big a problem. I know i can put in a light thats's ON as long as there is power to the pump, but I want a light that's OFF when the pump has power and ON if it loses power.

use a relay.

quote Originally posted by crashyoung: use a relay.

yep

[This message has been edited by GraterFang (edited 07-03-2012).]

You can use a Bosch relay from any auto supply store to do what you want,but why? If the light is not in the mode it should be in,you know something is wrong.

I'm assuming you're running a V8, if you have programming logic for a second fan in the code and programming access, I'd use the second fan control logic to turn on a buzzer or light at a preset temperature. I've missed my temp gauge a few times when the coolant temp was getting on the high side and under the right distracting circumstances might miss a warning light. Engine light orange might be better than a red warning signal.

why not hook up the dingy thingy to go on if the temp gets too high?

The temperature gauge is your best indicator of cooling system operation. As for checking the pump itself; the only thing that would help is if you installed a flowmeter switch inline and a dash indicator to check if the pump is functioning and that the water is circulating. Such a setup might not come cheaply.

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I use a relay to turn the pump on, but I do not turn it on manually. What I want is a wiring diagram that shows me how to put a light on the dash that tells me when the pump is not running - not if it's not pumping water. Please don't just tell me to "use a relay!" I don't know if you mean you think I should use the relay to manually turn on the pump and have a light somewhere on the dash come on or what. I guess I'm dense - I need more info. And yes it is a SBC. I wired it for auto ON so I don't forget to turn on the pump. Again, I just want a warning if power to the pump is lost not an indication of low or no water flow.

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87 GT, Ramjet 350 SBC, 6-Spd
Melbourne, FL

quote Originally posted by Dennis LaGrua: The temperature gauge is your best indicator of cooling system operation. As for checking the pump itself; the only thing that would help is if you installed a flowmeter switch inline and a dash indicator to check if the pump is functioning and that the water is circulating. Such a setup might not come cheaply.

Monitor Pump's amps...
Too high or low and pump and/or system itself have problem.
Too high amps can also be low volt. (See my cave, electric motor in electrical section.)

relay...
Need a SPDT type. Wire buzzer/lamp to relay "Normal Close" contacts. Relay will close w/o power to activate the lamp.

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(Jurassic Park)

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Crude, but MS paint was what was easiest to use right now...



use the NC side of the relay, and use a "Hot in Run only" +12V source.
Splice the relay into the pumps wire...
I usually choose the ground side for an application like this, as the Positive side is usually switched on and off by something else...
I did this on another car for a different application (fuel pump), but same idea.

-Dave

That will not really do anything for you. It will only tell you if the pump is being told to run, not if it is really running. Not counting a blown fuse, I think, in most most pump failures, you will still have power to the pump. But if you want to do it this is dead simple and cheap: When both the LED and pump have power the light will be off, when the pump looses power the LED will be grounderd through the pump and will light. No relay at all. If the pump goes bad the light still will not light. Larry

quote Originally posted by trotterlg: That will not really do anything for you. It will only tell you if the pump is being told to run, not if it is really running. Not counting a blown fuse, I think, in most most pump failures, you will still have power to the pump. But if you want to do it this is dead simple and cheap: When both the LED and pump have power the light will be off, when the pump looses power the LED will be grounderd through the pump and will light. No relay at all. If the pump goes bad the light still will not light. Larry

But if the pump fails open, or you lose a ground, the light will not illuminate.

quote Originally posted by phonedawgz: But if the pump fails open, or you lose a ground, the light will not illuminate.

Maybe a combination of approaches is the answer. Doesn't one of the AC high and low pressure switches activate with an open circuit and the othe activates with a loss of ground. I sort of remember something along those lines. Looks like I need to find an electrical engineer to solve the problem - I thought there might be a simple solution!

Yes, but the relay solution will also give a false indication. Larry

Most of the above will only let you know if there is power to the water pump, if the pump itself fails there will be no warning. I say use a good temp sender and possibly an idiot light off that and pay attention to it or mount it some where that you will easily notice. Dan

Like Ogre said, you need to monitor current.

Find yourself a 12v DC current sensing relay so you can tell if the pump motor is drawing current. Usually you just thread the conductor for your pump through a loop in the relay and wire up your 12v and whatever output you want at the relay.

quote Originally posted by theogre: Monitor Pump's amps... Too high or low and pump and/or system itself have problem. Too high amps can also be low volt. (See my cave, electric motor in electrical section.) relay... Need a SPDT type. Wire buzzer/lamp to relay "Normal Close" contacts. Relay will close w/o power to activate the lamp.

I have a good temp gage, but if the pump goes out the temp spikes really fast (experience). So I think your suggestion to add an ammeter and a relay with buzzer/lamp to monitor the pump motor is the solution - maybe I'll put the meter and buzzer lamp on the windshield post where it will be in my face. Thanks very much!

Ogre is right, and that was my first answer (its the best solution because it gives you more info, and as an engineer I usually like that). I've been thinking about this alot because I want to put a forward mounted meziere (sp?) in my baby at some point. Moves weight forward, electric pumps are lighter, and I can get rid of the heater core tubing running front to back.

However, simpler, more cost effective solutions include:

Flow switch plumbed in line
http://www.mcmaster.com/#flow-switches/=jokmhk

or, even better because there's no head loss across the sensing element:

Differential Pressure Switch connected to the upstream and downstream side of the pump. Something like this:
http://www.ebay.com/itm/NEW...&hash=item5ae66e178b

mfr page:
http://www.dwyer-inst.com/P...hes/Series1800/Specs

I will likely be getting one of these when I make the move. You would need to run a couple of hoses to this thing and place it in a non-wet area. Spare tire tub is a nice place!

Principle of operation for those not engineers: When the Differential Pressure (DP) switch sees no pressure differential across a pump... it is not pumping. When it does see pressure across a pump, then it is pumping. Engineers call this pumping Total Dynamic Head (TDH).

I am not sure what "normal" system head is across a fiero cooling system, but anything greater than zero means the pump is on and poppin' as the kids say.
Hope this helps,

Mike

The switch manufacturer specs state

quote Service: Air and non-combustible, compatible gases.

[This message has been edited by phonedawgz (edited 10-12-2012).]

Current Switch with Relay - Looks like this will provide the required functionality http://energycontrol.com/Veris_Hawkeye_H958.aspx

[This message has been edited by Driver_WT (edited 10-13-2012).]

A hall effect IC sensor - It has less than 0.0001 v drop across the current path and it is electrically isolated

http://www.rlocman.ru/i/Fil...uits/MAX4080FAUA.pdf

Would need both a relay, and a circuit similar to what was posted above. The relay would let you know if you lost power TO the motor, and a set up similar to what is in the link, (only across the motor not before it, the motor replaces the fuse in the diagram) to let you know if you lost THE motor. This works on the principle that current follows the path of least resistance.

https://rockwellautomation.custhelp.com/ci/fattach/get/12822/1202768727

Now if the motor itself shorts out to blow the main fuse, you would want another indicator there too, making it three things to set up.

Idiot light seems the easiest, but I can see why you would want the other set ups as well.

Kevin

[This message has been edited by Lambo nut (edited 10-13-2012).]