wired up fan switches, almost caught the car on fire

buddyf87

buddyf87

Member
Jun 27, 2005
94
0
6
Clarksville, TN
#1
so i wired up 2 fan switches the other day (high and low speed), and today i was sitting with the car and switches off and notice a little smoke coming from around the plate i mounted them on. so i yanked it off and 2 of the wires were smoking with the insulation burning off. the odd thing is it was the ground wire on the low speed switch, and the accessory wire on the high speed one. also, this is while the car and switches were both OFF. so i grabbed a tshirt and pulled them off. none of the wires are exposed or touching, but i did just run one ground wire to the engine bay and splice it into 2 to go to both the switches, and the power wires are individually wired straight to the battery (so i can leave it on between runs at the track). now im scared to hook them back up cause i dont want to come out to my car burned up one morning. anybody know why it would do this?
 
#2
How are your switches configured? This doesnt sound like the typical CCRM Pin 14 and 17 switches.

More info about exactly what was done and we can get it straight.

Good luck.
 
#5
i just cut the wires coming off the fan and ran a 16 gauge wire into the cabin straight to the switch. not sure about the switches, i just got 2 from advance and hooked them up. this was my first time wiring anything so chances are i did do something stupid and unsafe.

EDIT: so the general consensus on corral as well is that the wires were too small, i should have run relays with a small wire going to the switch so it wasnt carrying the load, and also run fuses. the bad news is that im new at this and i dont know how to do relays or fuses. some pics of how to wire them would be appreciated.
 
#6
buddyf87 said:
the odd thing is it was the ground wire on the low speed switch, and the accessory wire on the high speed one. also, this is while the car and switches were both OFF. so i grabbed a tshirt and pulled them off. none of the wires are exposed or touching, but i did just run one ground wire to the engine bay and splice it into 2 to go to both the switches, and the power wires are individually wired straight to the battery
Click to expand...


If I am understanding you right on this, your power wire is run directly to the battery and you are running the ground wire to the switch? If this is the way you have it done, STOP. More than likely you have a direct short and it can't do anything but burn the wires until it goes away. Give us some details on the system and we can get it wired up for you. Just always remember the main thing, Fuse it and maybe fuse it again so things don't burn up.


Paul
 
#7
Oh Man

You Cannot just run some wire from there fans yo. You got 40 amp's running thru there in high temp as well. The wire rating for that application is about 10-12 Gauge with Teflon Insulation or Silicon. Also you need a 40AMP Cracker Relay in there so you dont have to bring all that juice to the switch and a Fuse is also a must. I have that same setup in my car now and it works like a charm.
 
#8
correct, my power wires are straight to the battery. the switches have 3 prongs, top for power, middle for accessory, bottom for ground. so yes, i ran a ground wire from the switch.

also, i just got my dad whos a mechanical engineer to explain it and he also got his friend (an EE) to do some more splaining so i get what a relay is. now im wondering if itd be easier to just rip out the 16 gauge i have going to the fan and replace it with a 12 gauge (with fuses obviously) just so i dont have to mess with a relay.

heres a quick paint drawing of how it is now, i only drew one cause theyre both wired the same (all the wires are currently unhooked on the switch)

http://i74.photobucket.com/albums/i268/buddyf87/switch.jpg
 
#9
If you are new to electrical wiring... just run a switch with ground to the high speed ground wire. No electricity to mess with. All you are doing is providing a ground on a switch. You turn the switch on it grounds the wire, and turns the fan on high.

That's all I have. One wire on one of those fancy little cover switches running to the front of the car. :shrug:

http://www.allfordmustangs.com/Detailed/499.shtml
 
#10
Since your Dad's an engineer, he will explain the importance of the relay. Don't skimp here. I'd run a 75 amp Bosch relay if it were me.

If you still have the stock fan wiring intact, going with Paul's idea is good. You utilize the OEM wiring and relays, simply adding an addition relay-coil trigger to each respective relay. Quick and easy and maintains OEM function and reverse engineering compatibility.

If you get fed up and want the best fan controller out there, get a Dc Control unit ( www.DcControl.com ) and be done with it. The kit is complete and no relays are used (it uses PWM for infinitely variable fan control. If you're not familiar with PWM, your dad or his friend can tell you how cool it is. :D ).

Good luck.
 
#12
I personally would use 10 AWG for the load side wiring.

Are you running one or two speeds? If you will only use high, I'd use the Bosch 75 amp relay (that I already mentioned), which is in your link.

If you want to run low and high, you can probably get away with a SPST or SPDT conventional relay for low. Given how things have gone, I'm wondering if this is even worth it.

If your EE friend wants to help, you can use a 3rd SPDT relay so that when high is turned on, low turns off.

And none of it has anything to do with having the light be functional on your switch.

Be sure to use a freewheeling diode to preserve your relays. When the fan is shut off, it produces a nice (huge) voltage spike which backfeeds the circuit. The diode quells the spike to ground.

Good luck.
 
#13
the reason im running 2 speeds is ive read that turning the fan from off to high can cause problems.

one last question, since the switch has 3 outlets, i just leave the power one unhooked? i didnt even know they made a switch with just ground and accessory outlets as described in pauls link. and thanks hissin for all the help, i really appreciate it.
 
#14
buddyf87 said:
the reason im running 2 speeds is ive read that turning the fan from off to high can cause problems.

one last question, since the switch has 3 outlets, i just leave the power one unhooked? i didnt even know they made a switch with just ground and accessory outlets as described in pauls link. and thanks hissin for all the help, i really appreciate it.
Click to expand...

Ok, good plan with the dual speeds. Your info is correct (I've posted it myself :D ).

Assuming you want to switch 12 volts to your relays (we can switch either power or ground - just let us know before we type too much stuff up. It is just as easy either way. Switching 12 volts makes it easier to illuminte your switches though):

Your switches will have:

12 volts into the switch (going to the source terminal).

A wire leaving the accessory terminal of the switch and going into the engine bay to terminal 86 of your relay.

Then you can indeed run a wire from the ground terminal on the switch to a grounded bolt near your switch. WHen power goes through the accessory terminal, the switch's light will come on. Back when I had fan switches, they were lighted and could function as such:

92533.jpg


Regarding Paul's link: the switch isnt anything special. One of the switches in my panel functioned as the one in the article (my switches mimic what was done in the article, since I had to keep the OEM fan control functional originally). Here's how you'd do that: Run a wire from ground to the 'source' or 'power' terminal on your switch. Then whatever is connected to the 'accessory' terminal will be connected to ground when the switch is activated.
Switches like these dont care if you are putting power or ground through them. Please don't mistake the 'ground' notation on the 3rd switch terminal as being some ground pathway for the actual switch itself - it's ONLY to make the switch light up. They really should call that "If you are running 12 volts through this switch, connect the third terminal to ground to make the dippy light illuminate". Maybe that makes it clearer (I can see where them calling the terminal 'ground' could lead to confusion).



Good luck.
 
#15
ok, update and an odd problem. i rewired everything today to go to the ccrm (using fuses and relays). when i just hooked up a ground wire to the power terminal they didnt work at all, no lights or anything. so i hooked the power wires back up and moved the ground wires. heres where it gets weird. hooked up like this, the low speed only works with ignition on and the high speed only works with ignition off. both lights will illuminate either way, but they only activate the fan as described. also, my nitrous switch which ive never had a problem with before now doesnt work at all. does anyone have any idea why they would act like this?
 
#16
http://i74.photobucket.com/albums/i268/buddyf87/wiring.jpg

and another paint drawing of how its all wired. i would say its a loose connection somewhere, but i triple checked everything and since they both work predictably i dont know wth it would do this. the high speed and nitrous switch were using the same power wire before and i never had any problem with it. and with the high speed on the n2o still doesnt work if thats worth anything..
 
#17
You have some bad wiring somewhere. Neither speed should turn on without the key being on as I recall.

For now, remove the 3rd wire from each switch. Your switches won't illuminate but that is the least of your concerns.

Otherwise, I would start checking values of each wire (at the switches) with your meter. This will tell you where the issue is.

Good luck.
 
#18
for low speed hook up wire switch side of relay, hook BK/O wire from pin 3 of CCRM to one side of switch circuit in relay, hook R/O wire from pin 1of CCRM to other side of switch side of relay.
Hook a 15 amp fuse source to coil side of relay then hook your switch to other side of coil side of relay then hook other end of your switch to ground.

If you are going to run a switch for high speed, hook switch side of relay to BK/O wire from pin 4 of CCRM or you can just hook to same wire as the one you used on low speed,hook other side of relay switch ckt to O/LB wire from pin 6 of CCRM.
Hook 15 amp fuse source to coil side of relay and hook other side of relay coil ckt to your switch then hook the other side of you switch to ground.

Pin 3 & 4 of the CCRM gets its power from 60 amp fan fuse in battery fuse box
Pin 1 of CCRM feed low fan, pin 6 feeds high fan. Or you can just run new wire to fan just make sure to use same guage wire as the ones already there.
 
#20
well after testing with the meter im even more confused. with the switches turned on, both of the wires going to the pins on the ccrm are getting power regardless whether the ignition is on or off. but the low speed still only comes on with the ignition on and the high speed still only comes on with ignition off. so the only thing i can think of is i tapped the wrong wires. i know i got #14 for low and #17 for high- hard to mess these up since theyre numbered and also since they will activate the fan at certain times.

chuck, you said #1 is for low speed and #6 feeds high speed. did i miss something here?
 
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