Hey guys,

I have a '97 LT1 SS with a Meziere electric water pump. I am trying to wire an LED that will stay lit whenever current is flowing through the ground wire for the pump. That is, I want to run an LED in series with the water pump, with the ground wire for the pump serving as the positive current for the LED.

This arrangement seems to provide the best indicator as to whether the pump is working. I have seen many circuit designs on the internet that purport to include water pump warning lights, but the warning lights in those circuits actually only ensure that the relay on the positive side of the pump is working. The wire connection going into my pump is a bit fickle. Testing current on the ground side of the pump will rule out a bad relay, a bad fuse, a bad wire going into the pump, and any electrical problem within the pump. Only a mechnical failure that does not impede current will go undetected.

This circuit at least addresses the ground side of the water pump, but it tests for a ground failure instead of normal operating current:

https://ls1tech.com/forums/lt1-lt4-m...waterpump.html

I don't see how a ground failure is a real threat. I want a light to illuminate when there is current flowing through the ground wire for the water pump, not when the wire I have securely bolted to the frame as a ground mysteriously comes loose.

So far, I've tried many different ways to do this, without success. I'm worried there is no way to do this. An LED only flows about 30 miliamps of current, so the 20 amp water pump won't run with all of the current flowing through the LED. I have tried a relay with the water pump ground as the trigger; the relay clicks on, but the water pump doesn't turn on because (I assume) the trigger side of the relay does not flow enough current to run the pump. I have tried an illuminated rocker switch, but the light won't turn on either when the pump is running or when there is no power coming through the pump. I've messed with a 12-volt diode spliced into the ground wire and then to the LED, and that doesn't work either.

I imagine the solution, if there is one, involves diodes, transistors, resistors, etc. - stuff I really don't understand. If anybody has a clue how to wire this, or can suggest an alternative circuit design that will accomplish the same thing (test for a charge coming out of the water pump), please help! Maybe there is a relay, or a way to wire a relay, that will solve this problem.

 

There are many ways to do this........i had designed a system i was going to sell that would do this but at a $40 price tag it just wasn't worth my time doing them unless i had many orders.......i used a relay system that would trigger a light to turn on if the pump lost ground or lost power for any reason at all..............the slightly more complex way to do it would be a current monitoring circuit with a transistor that would get biased when current is flowing thus inhibiting the light from turning on when current stopped flowing the transistor would loose its bias and the light would become powered vs. the transistor resistor load on the emmiter.......

anywho......lemme see if i cand dig up the schematic i drew for the relay style.......

 

found it..........



pretty simple idea.........if the ground or power wires break to the pump the light will turn on........if the pump shorts and fuse blows the light turns on........if one of the warning system wires breaks the light turns on..........pretty much covers the whole deal very simply

only change you need to make to this is the light relay power supply pin (87A) should be hooked up to 12 volts switched not battery otherwise the light will be on while the car is off...

 

Hey, thanks man. That's simple.

The ground side of that LED relay should always work unless there is some physical problem with the chasis ground or wire (which is highly unlikely), so really it tests for a positive signal going into the pump right where the positive wire enters the pump. It's close to what I am looking for. But what about when something electrical fails internally in the water pump without blowing the fuse? Isn't that a significant concern? These things just burn out, from what I've read. I don't think this circuit would catch that. Power would still be coming into the LED relay, and the chasis ground for the water pump and LED would still work.

Do you think this might work? LED hooked up to ignition switched power, with LED ground ran through a diode to the water pump's positive wire. When the pump is working (at least electrically), current is flowing downstream through the water pump positive wire, the pump, and on to the ground. But when the water pump is not working, the water pump positive wire is not connected through to a ground. So, when pump is on, a splice in the positive wire can serve as a ground. When pump is off, no ground for the positive wire. LED on when pump on, off when pump off. Think I'll just burn my LED and/or diode doing this? Would a resistor help?

Hmm...may be ok if I burn my diode or LED, as long as that happens only when there is power in the pump positive wire but the pump is not working. At that point, my LED light goes off and I know there is a problem. There would only be power in the pump positive wire when the pump should be on.

 

As an aside, this car has a 383 with AI 200cc heads, solid roller, hooker long tubes, and Ed Wright (fastchip) programming. It only dynoed around 400 rwhp (M6) and it has been sitting for about 6 years. Pretty soon, I'm looking to diagnose the power problem (may be blown head gasket(s) from this dumb *** water pump) and to get the expected power output. Would love to get anywhere close to the output you're getting from your 386, quik. Are you willing to share your dyno numbers, either publicly or through PM?

 

haha........dyno numbers? sure..........i made 475 misfiring and it has never been back to the dyno since..........i hate dynos......with a passion........i tuned my car solely at the track off of timeslip and DA/Air Data........


dont get caught up on dyno numbers.......

i had a few people laugh at me when the "loud" race car made 475 and the "cobra" with the supercharger made 550........ever seen a 475rwhp 3300lb 135mph+ trap car with a big stalled auto in it?? lol............that cobra didn't find it too funny when he called me out on the drive home from the dyno and got his teeth kicked in by the little LT1 that could ............dynos are a tuning/troubleshooting tool ONLY.........we race cars NOT dynos.........get ur car on the track

 

these pumps dont usually just "open"...........anyways...........here would be the ultimate fail of that idea lol..........lets say the fuse blows to the pump............you still have a ground connection and the light is on.........
lets say the pump shorts out...........still have a ground connection and this is a much more likely scenario...........

like i said easiest way out is what i showed you above this will protect you about 95% other than an "open" motor..........if not like i said before you'd have to run a current monitoring circuit which now looses the "simplicity" factor........

BSEE here btw lol

 

I completely agree... the way you have shown in the schematic is the easiest way without getting into a current monitoring circuit and requiring some circuit/PCB fabrication instead of just some relays.

 

Wow, easy there. Do you issue that response every time someone brings up a dyno? I understand the role of a dyno. Racing on a dyno just isn't quite as fun. But this car won't be seeing the track any time soon. I know your track times. I know what the setup I have typically puts down on a dynojet. Comparing the two gives me a frame of reference, obviously. It's all I have now.

Probably won't see north side of 130 out of my setup. 135 is impressive on 386 ci N/A.

Anyway, thanks for your help.

 

nah sorry i wasn't like directing anger at you lol......i just finished that argument with a friend of my sorry lol........in reality i honestly have no clue what my car makes.......i would immagine its around 700hp at the flywheel........yours should put down good power is the cam an AI also?? gotta make 450-470 i would think if its got good compression

 

Those are the numbers I was thinking: 450-470 rwhp and low to mid 120 traps. Not sure exactly where compression is, but I've been told around 11.X:1 (set up for 93 pump gas). Cam is AI solid roller 255/262, 668/662 on a 110. I have a flow chart that shows the heads flowed 279 CFM on the intake side at 650 lift. Hard to read the exhaust flow numbers, but they look to be just under 200 CFM at 650 lift.

I changed the six year old oil last weekend. Most of the oil was murky gray. That seems like coolant to me, though I'm not sure what 6 year old oil normally looks like. Anyway, these electric water pumps can be trouble. Just hope the long block's ok.

 

Thread sort of went off topic. Here is the easy way. Put a large diode in the ground wire. The small voltage drop across the diode will power the LED. If you get a diode that will handle the power, read the voltage across it and post it. I'll reply with the circuit.

The current draw and the diode you pick will dictate the voltage drop. Does the paperwork that came with the pump give the current draw?

Here is the type of diode you should look for. At 10 Amps and 1.2 Volt drop the diode will dissipate about 12 Watts so it will need a small heat sink.

http://www.nteinc.com/specs/5800to58...nte5864_89.pdf

Al 95 Z28

 

http://www.lt1engine.com/tech/electr...r-pump-wiring/

 

I never had a single issue with my EWP in the 40k miles I had it on my car...

 

Well my first one lasted a good while, then the one that replaced it lasted a 1/4 the time... So it's a hit/miss either way meziere warrantied the motor no questions..

 

Here's my question..

The Schematic is good..but when the Pump goes to **** does it stop drawing power?

Say it seizes up..is there some kind of fusable link in it that blows and stops incoming power?

 

Merv, I would guess there are circumstances where it would fail mechanically and yet still draw power. In that case, a circuit like this leaves you hot...overheated.

Al, tech specs on the pump say that it draws 6-7 amps during normal operation. Not sure how high above that level it could go. The supplied fuse burns at 20 amps. Thanks so much for chiming in. I still don't know exactly what diode I need, but it's good to know someone makes diodes like that. Could you guess at the best diode for this and point me to where I can buy it? Not exactly a Radio Shack item (place sucks now).

 

Just buy one of these and I'll explain how to wire it. You can put it in the hot or ground side and it will work the same. You will also need some heat sink compound and something to mount it on for a heat sink.

http://www.jameco.com/webapp/wcs/sto...0001_179485_-1

Al 95 Z28

 

i was trying to avoid something that is going to create alot of heat and require a sink in an already hot engine bay..... not to mention its yet another thing in the power circuit that if fails will shut the pump down.........also the diode is going to create a small voltage drop in the voltage potential to the pump probably around 1.1 volts with this diode......so you now lost some voltage to the pump........


like i said before the only thing that will not work with my curcuit is if the windings in the pump motor somehow just "open" and do not cause a short to pop the fuse which is extremely rare.......i had a pump of mine fail and when it did my fuse blew on the spot which turned the big red led on my dash on and i shut the car down.........

 

I'm not arguing his logic, I just answered his question with what he asked for.

Al 95 Z28