So I have been thinking about the cooling article I read, and how I did not see any wiring diagrams but wanted something similar.
Mind you, i have not added a temperature activation changer for the ecm yet (if I plan on changing thermostat to a 170), but am merely speculating on a system i have been designing.
The resistor shown i wont know what size it is until I find out how many ohms my fan is. But other than that, here is what I have been theoretically designing from scratch.
Anyone see any flaws in it yet? It's late so I doubt it is perfect lol.

My main goal is to be able to use the factory settings. Be auto to manually turn it on, and if the fan fails to activate, a buzzer will sound.
I just realized, that buzzer will probably always sound off/light be on using auto...doh i will try to fix lol
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Updated: Fixed....looking at ti again for flaws before i pass out... lol

 

Looks overly complicated .What are you trying to achieve?

Most just splice a switch to ground into the fan relay control wire that goes to the computer.
Switch on ; fans run continuously at any temp.
Switch off ; fans run at computer controlled temp

No need for warning bells or lights although you can connect a light to remind you fans are manually on if you can't read your temp gauge

 

Not even sure it'll work with the buzzer relay in there. Seems power will skip the fan and go strait to ground through the new relay. Also the Evil ECM only controls the ground leg of the relay, not two sides

A simpler method is to keep the very basic stock relay setup and simply Tee into the dk grn/wht wire from the relay to the ECM. This is the ground call, so use a toggle switch to ground. With the switch off, its in auto mode with the ECM. With the switch on, the fan runs continuous with the IGN on. You can buy LED toggle switches to announce you indeed have the switch turned on, but those shouldnt even be required because the stock fan is quite loud

 

Actually, the LED won't light in this scenario. I tried doing the same thing in my Camaro since I swapped out the 3.1 for a carbed 350. I tried everything I could think of to get the light to come on but the way the light in the switch works it just wasn't going to happen.

I eventually wired an LED off the main power wire to the fan. I just spliced into the red/black fan power wire right before the fan's connector and ran a wire in to the cabin to an LED with the proper resistor and then to ground. I still have manual control of the fan this way, and the LED lights up whenever the fan comes on whether I turn it on manually or the fan controller I installed last winter turns it on.

I also think the buzzer would be annoying. The fan won't run when the car is shut off so I don't see the need for the buzzer to remind you its on?

As for the schematic itself, the resistor for the LED should be right at the LED, not on the other side of the relay. I don't think the buzzer would need to have the resistor, but without knowing the specs on it I can't be sure.

I'm not sure about current bypassing the fan as Pocket mentioned(I don't see how it could, but maybe he's seeing something I'm not. I am looking at this while at work so its entirely possible.). However, the Evil ECM does not provide + voltage to activate the relay coil, it provides the ground path for the coil.

Let me see what I can come up with, there is a much simpler way to do this. I'll post a diagram up later for you.

 

Read the directions on the LED switch. It requires an external 12v source not related to the toggle switch function

 

The first problem I see is that the ECM normally provides a ground. Your circuit shows the ECM providing power. That renders your circuit invalid. But let's assume that your car is wired this way.

The way this circuit is drawn will not work as you hope it will. Assuming that everything is correct, the result will be that the fan will operate either auto or manually, but any time the relay is energized your buzzer and light will go off. Further, that will happen even if the fan is removed from the circuit. The way you have it drawn, the fan and the buzzer are in parallel, which means that they will operate independently of each other.

 

Yes, I know. The problem is, the switch is wired to connect the +12 to the ACC position and through the LED to Ground. If you use the wire from the fan relay at the +12 connection, it goes straight to ground and not through the light due to the resistance provided by the light. And you can't run battery voltage to the +12 connection since you are trying to ground a wire with the switch. Unless you're using a different type of switch than I tried.

As for the diagram, below is a much simpler way to wire things. You'll need to work out the value of the resistor based on the LED you are using. I believe I used a 1/2 watt 330-Ohm resistor on mine. I tried to use the same colors as the factory wiring where possible, but that is based on a 92 Camaro with a 3.1, yours may be slightly different. Everything in blue is what you would be adding.

 

92 RS, yours is a much cleaner circuit, and more correct. However, as I stated above, this will make the buzzer sound any time the fan is energized. If I read the OP correctly, he wanted the buzzer to go off in the event that the fan did NOT energize.

 

I missed that part. I thought he wanted the buzzer to activate while the fan was on. No wonder it didn't make any sense to me.

That's gonna make it a lot messier

 

Here's the messier version. I think this should work the buzzer correctly.

 

You have a couple of problems:

• The connection from terminal #85 on the buzzer grounding relay is at ground potential. This gives you ground potential on both sides of the relay coil, which means it will never energize.
• As a result, your buzzer will be powered any time the fan relay sends power to the fan.
• The other relay is feeding power to the buzzer, but only if the fan relay is feeding power. If it isn't, your buzzer never gets powered up.

 

In order:

You're right, I'd have to ground the fan through the relay which probably isn't a good idea.

I do want the buzzer powered any time the fan is on, but only able to ground if the fan does not turn on. This will only allow current to pass through the buzzer when the fan is supposed to be running but isn't.

True, but I am assuming the wiring is ok, but the fan is dead in this schematic. If the fusible link to the fan blows then the buzzer will not work.

I'm not sure how you would be able to have a buzzer go off if the fan is not working otherwise(to account for a blown fusible link basically) without actually measuring the fan RPM or the voltage drop across the running motor. Either of those would most likely involve custom-programming a microcontroller or some other type of IC chip which is currently beyond my skill level(although I'd really like to get into it at some point if I can ever find the time) and I'm assuming beyond the OP's as well.

 

You could always do the baseball-card-in-the-spokes trick to make a buzzer. IE - attach a small strip of plastic to on of the fan mounts in such a way that it extends into the fan blades so they hit it when the fan is spinning making a "buzzing" sound. Easiest way to do this would be to wrap a ziptie around one of the support arms with the excess extending into the fan blades.

Actually, if you bend the lower lip of the radiator support closer to the fan blade you will get the same effect. My Camaro had this issue and it took me forever to figure out what was causing the noise. I went through 3 blades before I realized it was the radiator support and not the fan blade that was twisted out of shape.

 

Heres my updated one. If the resistors resistance is higher than the fans, voltage will not leak through correct? If so, shouldn't that resistor be fine until the fan goes OL?
And I don't know wth I was thinking last night....why I had power feed coming from Ecm.....my electronics teacher would kick my ***. LOL

 

No, you have a parallel circuit between the fan and the buzzer relay. That means the voltage will be equal across both branches. Inserting a resistance will cause a proportional voltage drop across it.

If x = (voltage drop across resistor) and
y = (voltage drop across buzzer),
x+y = 12V = (voltage drop across the fan).

The value of resistance that will prevent the buzzer from running when the fan is on will also prevent the buzzer from running when the fan is off, because in both cases, the voltage is the same.

RS, the real problem here is that we have to define what constitutes a fan failure. It could be caused by lack of power, lack of ground, or failure of the fan motor. It would be difficult to draw a simple circuit that would cover all of these conditions. But even if you ground the fan through the relay, you are still not going to sense a fan failure that way.

Ideally, you'd want to use some sort of current sensing device (think ammeter instead of voltmeter) to read current passing through the fan circuit. Absence of current triggers buzzer relay IF the fan is powered.

 

 

Now THAT is the perfect solution. This way, you get exactly what you want -- a warning that your fan blades are not turning. Excellent call!

 

I agree, that's a great idea. I was thinking along the same lines with using a crank sensor with the magnetic trigger wheel but couldn't come up with a good way to mount it to the fan blade so I didn't mention it.

I'm not sure how you would get the buzzer to read that though as I'm not that familiar with them. I would guess that would create a "pulsed" signal which would then cause the buzzer to activate intermittently would it not? If that is the case, how would you turn that "pulsed" signal into a constant signal for the buzzer?

 

 

A few things ide like to mention based on your last schematic. Now obviously as mentioned the fan and the buzzer will always work together which is not good you need to make a circuit that detect a fault to ground the relay that controls that circuit. However also having the LED and buzzer in parallel probably wont work either. Problem is led will by their nature have a fixed voltage across them depending on what color led your using. It would probably be somewhere around 2-3V. This means the voltage across your buzzer will also be 2-3V. This is ok as long as your using a buzzer designed to work down on those levels but my guess is your probably using a standard 12 V deal so that will not work. What you need to do is put the resistor in series with the led and put the LED/resistor combo in parallel with the buzzer. Next for the fan youll want to use a fuseable link not just a standard auto blade type fuse. Lastly on how to detect a fault in the fan? Although i like the solution posed in a previous post there is one issue I can see. When moving on like the highway for example the fan will be spinning whether its on or not just by virtue of the fact air is blowing through the radiator hitting the fan. If you were to do it this way it could still work but you would have to do it in such a way that it would also figure that the fan should be spinning at least a certain RPM. This could also be done relatively easily done but again I dont know how much of a project you want to make this lol. This also does also not account for the possibility that the fan is working when its not supposed to be though I don't know if you want to include that.