LED to indicated fan ON/OFF

[CDeeZ]

Hey everybody,

So I was killing time in radioshack the other day and I was browsing the LEDs and I got an idea...... I'd like to put an LED in my dash that lights up when my Efan is commanded on by the PCM...

I guess an LED really isn't that complicated, but I was reading up on it on the internet and it is definitely not as simple as a conventional incandescent bulb!

My question is this: how do I know if the LED i selected will work properly in my Efan circuit?? I could just wire it up and be ready with the fire extinguisher :rolleye: LOL.

Specs: Forward Voltage: 12.0 TYP, 16.0 MAX

Forward Current: 15mA TYP, 25mA MAX

The LED also has a built in 680 ohmm resistor........

Will this LED work okay in my Efan circuit?????? I've been playing around with it on a spare 12v battery in my garage and it seems good to go that way.....

Thoughts?

[PJG1173]

I did this with regular mini bulbs. I tied into the power actually going to the fan after the relay vise looking for when the pcm commanded the fan on. that way I can see when and verify the relay controlling the fan is activated. I have been looking at using LED's vs regular bulbs in my setup because when the fan spins even with out it being on the bulbs will light up and get brighter the faster I drive. I am hoping the LED's don't do that, any how I was planning on wiring them in the same way but with a diode in series to get rid of the small voltage signal the fans produce while spinning without power applied.

[gregs78cam]

...

Will this LED work okay in my Efan circuit?????? I've been playing around with it on a spare 12v battery in my garage and it seems good to go that way.....

Thoughts?

Sounds like it should work fine.

[RobertISaar]

that LED will be fine. with the current it needs(minimal), you can either tie it into the switched ground for the control portion of the relay or on the load switched side of the relay and it will work fine.

if you want a mspaint diagram, let me know. :laugh:

[91ss]

If you wire to the load side of the fan, you may see it light up some at highway speeds as it may turn fan fast enough to generate some electricity.

[PJG1173]

If you wire to the load side of the fan, you may see it light up some at highway speeds as it may turn fan fast enough to generate some electricity.

there's no may about it. it does, but it is so dim its hardly noticeable

[EagleMark]

OK, I'm all for cool stuff, but what is the purpose or need of this LED indicator? I think I'd rather have the opisite! If fan did not turn on when supposed too then Light on? Assume all is well until not... except for the Nitrous Armed light! :happy:

[RobertISaar]

depending on the application.....

a lot of clusters got "check guages" or even a direct "engine hot" light that came on when above a specific temp... it's always way too high from the factory and requires changing resistors on the backside of the instrument cluster to "tune" it to the temp of your liking.

[Six_Shooter]

Specs: Forward Voltage: 12.0 TYP, 16.0 MAX

Forward Current: 15mA TYP, 25mA MAX

The LED also has a built in 680 ohmm resistor........



It's a 12V LED (due to the 680 ohm resistor to limit current), so treat it just like a conventional bulb, with the only exception being that it is polarity sensitive, so you need to make sure you have the polarity correct or it won't work, and likely damage it.

To use an LED like this on the fan side of the relay, without the feedback voltage created by the fan spinning due to airflow through the fan at speed, you would need to split the fan wire between the relay and the fan, placing the stripe towards the fan (electrically speaking), and connect the LED on the relay side of the diode. You will need to use a rather large diode, or several paired up in parallel, to live through the current that the fan demands.

If you wanted to have the fan turn on only when the fan is both commanded on by the ECM and the relay activates, you can connect the anode (positive connection) to the output (fan side) of the relay, and the cathode (negative side) to the control wire (since it's a negative trigger in the GMs), this would also eliminate the LED being turned on when the fan is being forced to spin at speed.

[CDeeZ]

If you wanted to have the fan turn on only when the fan is both commanded on by the ECM and the relay activates, you can connect the anode (positive connection) to the output (fan side) of the relay, and the cathode (negative side) to the control wire (since it's a negative trigger in the GMs), this would also eliminate the LED being turned on when the fan is being forced to spin at speed.


I wired up the LED the way you described, I think. The LED seems to work, but when the fan comes on at temp, the LED blinks for a few seconds before it lights solidly. Is this normal? I think one of my fan relays (2 relays, 2 fans, 1 relay per fan, both triggered by PCM) might be going bad. A couple times, one of the two relays has failed to turn on the fan, I grabbed them and was looking at them and one started clicking a bunch like the armature was going crazy inside, then they mysteriously started working again.

+ on LED is wired to the wire that runs from the relay to the fan (pin 87 on relay)

- on LED is wired to the trigger wire from PCM

[PJG1173]

I wired up the LED the way you described, I think. The LED seems to work, but when the fan comes on at temp, the LED blinks for a few seconds before it lights solidly. Is this normal? I think one of my fan relays (2 relays, 2 fans, 1 relay per fan, both triggered by PCM) might be going bad. A couple times, one of the two relays has failed to turn on the fan, I grabbed them and was looking at them and one started clicking a bunch like the armature was going crazy inside, then they mysteriously started working again.

+ on LED is wired to the wire that runs from the relay to the fan (pin 87 on relay)

- on LED is wired to the trigger wire from PCM

you don't have soft start enabled do you?

[RobertISaar]

i wonder.....

either soft-start or it's due to the fan spooling up.

[CDeeZ]

I didn't remember enabling soft start when I applied the code. But I went into hexeditor and checked and I do in fact have soft start enabled... Forgive my ignorance, but what exactly does softstart accomplish?

[RobertISaar]

if using a solid state relay or a good FET, then it will allow the fan speed to ramp up instead of drawing a large surge of current instantly.

if using it with a normal automotive relay, then you get the crazy relay shuttering.

[CDeeZ]

Ok thanks. I switched the hex around so I don't have softstart enabled and now the light comes on solid the first time.

Going down the highway the LED stays lit most of the time... I think I have a thermostat that needs replacing because it acts like it sticks a little bit, could this be why the fan is coming on/ staying on at highway speeds???

Or, do I need to change the fan settings?

Here's some pics for those of you who are like me and like the visuals:
http://i1301.photobucket.com/albums/ag113/chase238/DSCN3014.jpg

[Six_Shooter]

If it comes on at highway speeds, it isn't an LED, and is still kinda odd that it would if you did wire it across the trigger and outputs of the relay. An LED will only work when forward biased, when the relay is not triggered it would be reverse biased, and not light up. The coils in the fan itself should be enough to provide a high resistance ground when reverse biased and not blow the LED.

A light bulb, will light up when biased in either direction, meaning there is no positive or negative connection of a common light bulb.

If I'm recognizing the lights from the picture they are definitely not LEDs, but light bulbs inside coloured lenses.

[CDeeZ]

I think the fan is being commanded on at highway speeds by the PCM... I'm running a 195*F T-stat, Temp for fan ON and OFF set to 194.9 and 193.6 respectively. "overheat temp for fan on" set to 196.3.... maybe I should raise this one....

Here are the LEDs from radioshack that I'm using. Are they really not LEDs???????? http://www.radioshack.com/product/index.jsp?productId=2062569

[Six_Shooter]

Hard to tell even from the RS picture, but I've seen that style housing used with non LED type lights. The resistor could indicate they are LED, but not a definite.

[CDeeZ]

Well if they sell it as LED, but it isn't, how do I know either way?

[Six_Shooter]

You'd have to take it apart, or look VERY carefully for something inside that looks exactly like this:

http://upload.wikimedia.org/wikipedia/commons/3/37/Diodo_LED_verde.jpg

The only variation would be a clear diffuser, which would look the same internally, just not green (or red, or yellow), like the above LED:

http://2.bp.blogspot.com/-kLN0DDwjFv0/T86Z6T4V8uI/AAAAAAAACGY/NS7lJ3q2_to/s1600/whiteLED.jpg

LEDs only work with polarity connected in the correct direction, Anode being attached to a positive current, and cathode being attached to a negative current, so if it turns on when connected in reverse, it will not be an LED.

I seen many lights over the years sold as "LED", but in reality were not, not sure how or why, but I've seen it.

[RobertISaar]

you need to loosen up those fan on/off temps.... try 205 on, 200 off.

[brianko]

If you want to determine the value of the dropping resistor to use, subtract the voltage drop of the LED (usually 3V, sometimes higher, but not by much) from line voltage (say 12V). Then divide that value by the LED max current rating (usually 15ma or less). So for a 3V/15ma LED, the proper resistor to use is 600 ohms (there are no 600 ohm resistors, so round UP to the next value, which is 680 ohms.

Be careful: Not all LEDs have built-in resistors.

Oh, and most GM e-fans are controlled with a PWM signal, so your luck with using LEDs to determine when they are on will vary with the type of LED you're using. (This is why you can't use automotive LEDs on some GM DRLs, as they are PWM-driven as well.)

[PJG1173]

I think the fan is being commanded on at highway speeds by the PCM... I'm running a 195*F T-stat, Temp for fan ON and OFF set to 194.9 and 193.6 respectively. "overheat temp for fan on" set to 196.3.... maybe I should raise this one....

Here are the LEDs from radioshack that I'm using. Are they really not LEDs???????? http://www.radioshack.com/product/index.jsp?productId=2062569
I have a 185 tstat, my on temp is 195 and off is 185. If the off temp is below the tstat opening temp your fan will never shut off at operating temp. my overheat is 200 and mph to shut fan off is 55.

[CDeeZ]

Originally I wasn't aware of the fact that LEDs are polarity sensitive and when I first pulled the LEDs from the bag I hooked up the power both ways thinking (erroneously) that the current would flow either way, just like an incandescent bulb... They only light up the one way + to + and - to -, so that must mean they are in fact LEDs.....

I loosened up the fan settings. I'm not in front of the PC I use to tune so I'm going from memory here, but I think I set the fan ON temp to 198 and fan OFF temp to 194. I also raised my fan overheat temp setting to 215 or something like that. I drove down the highway to the GFs house last night and the fan shut off and stayed off during the highway run. Once I exited the highway and entered town the LED and fans came back on like normal. Seems all is well. I could raise the fan on and off temps even more I suppose, since I'm running a 195 Tstat, but if the fan shuts off and stays off while on the highway, and turns on when needed in town, sounds like I got it working about as good as it can.

Do you guys think I should bump up the fan temps a bit more??
Thoughts?

[PJG1173]

Originally I wasn't aware of the fact that LEDs are polarity sensitive and when I first pulled the LEDs from the bag I hooked up the power both ways thinking (erroneously) that the current would flow either way, just like an incandescent bulb... They only light up the one way + to + and - to -, so that must mean they are in fact LEDs.....

I loosened up the fan settings. I'm not in front of the PC I use to tune so I'm going from memory here, but I think I set the fan ON temp to 198 and fan OFF temp to 194. I also raised my fan overheat temp setting to 215 or something like that. I drove down the highway to the GFs house last night and the fan shut off and stayed off during the highway run. Once I exited the highway and entered town the LED and fans came back on like normal. Seems all is well. I could raise the fan on and off temps even more I suppose, since I'm running a 195 Tstat, but if the fan shuts off and stays off while on the highway, and turns on when needed in town, sounds like I got it working about as good as it can.

Do you guys think I should bump up the fan temps a bit more??
Thoughts?
Aftermarket fan controllers usually have you set the on temp about 5-10* above your normal operating temp. I found this in the instructions for the electric fan controller I put in my jeep. I when I applied that to this tune I noticed my efans didn't run as much with no real change in engine operating temp.

[CDeeZ]

The custom LED-fan indicator is working great. I ended up changing the ON and OFF temps to 205 and 200, like you suggested Rob. This seems to work best. Thanks every1!!!!!1!!!!1!!!!!!

[84Elky]

You may have already solved your problem, but these will work wired into the hot wires going to your fan(s). Just ground the other side under the dash somewhere. They come in green and red. Green are bright enough to see in daylight and subtle enough to not distract/blind you at night. Don't know about red but should be same.
RadioShack #276-0085, 1/4W, includes 660 ohm resistor for 12VDC operation (power dissipation = 180mW, forward voltage = 12V, forward current = 15mA).

[CDeeZ]

Yeah the LED has been working great so far!

[Six_Shooter]

You may have already solved your problem, but these will work wired into the hot wires going to your fan(s). Just ground the other side under the dash somewhere. They come in green and red. Green are bright enough to see in daylight and subtle enough to not distract/blind you at night. Don't know about red but should be same.
RadioShack #276-0085, 1/4W, includes 660 ohm resistor for 12VDC operation (power dissipation = 180mW, forward voltage = 12V, forward current = 15mA).

There's no problem with the LED working, the issue is the voltage created by the fan when it is spinning due to teh air flow through the fan when the vehcile is at highway speed. This will also cause the LED to illuminate.

[one92rs]

http://img.photobucket.com/albums/v157/02denali/car/DSC05290.jpg
in the pick you can see the 2 small rocker switches. between them is a 12 volt light buld such as the one you posted. one switch is 100% on and the other 100%off. i hooked the light on the load side of the fans AT THE FANS CONNECTOR! that way i know i am getting power to the fan pigtail. when i am going down the freeway it will light dim due to the fans turning and getting feedback. i am using a flexalite controller right now. it comes on at 60% and works its way up from there if needed. it is never needed.

[96lt4c4]

These are just temporary, across the PCM output and switched 12 volts. You can see fan A pulse when it turns on. I need a little hotter thermostat.

https://www.youtube.com/watch?v=RaFM2D17JI0&list=UUcGH4muS1IrlCjt39GkzvXg&index=1&feature=plcp

[CDeeZ]

There's no problem with the LED working, the issue is the voltage created by the fan when it is spinning due to teh air flow through the fan when the vehcile is at highway speed. This will also cause the LED to illuminate.

My LEDs do not illuminate at all from the fans spinning at highway speeds. They're only illuminated when the PCM commands fan ON.



between them is a 12 volt light buld such as the one you posted. one switch is 100% on and the other 100%off. i hooked the light on the load side of the fans AT THE FANS CONNECTOR! that way i know i am getting power to the fan pigtail. when i am going down the freeway it will light dim due to the fans turning and getting feedback. i am using a flexalite controller right now. it comes on at 60% and works its way up from there if needed. it is never needed.

Mine is not a light bulb!!! It's an LED. It has an anode, a cathode, .... it only works with polarity the right way....

:rockon:

[CDeeZ]

http://www.youtube.com/watch?v=vwNwMbGyubA&feature=youtu.be