Help with wiring a DPDT switch
 

I just ordered a DPDT switch from here (the fan one)

http://www.4x4mods.com/Product/Jeep/rockerswitches.html

and i don't quite understand the wiring diagram at the bottom of the page. It says one of the poles must be grounded, but the reason i needed a DPDT switch is bc i have two sources of power. I'm sure the reason for their diagram is bc of the built-in LEDs in the switch, bc it has to be grounded somewhere to complete the circuit for the lights. Is there anyway else to wire this switch where both poles are + but the lights on it work also?

TIA

Do you mean pole #2? That's the ground for the LED's in the switch it's self. It MUST be ground for the LED's to work. I'd need to see the actual diagram for the switch it's self to determine any other info on it. I'm sure that if you wire it the way they show when you get the switch, it'll work fine.

well my plan was for this to control my FAL electric fans

M<----| o o | (empty)
12V-->| o o | <--A/C Clutch
+ <----| o o | ---> C

M goes to M on the control unit

The 2 power sources are from the battery (12V) and the A/C Clutch (on seperate poles)

+ and C each go to the control unit

if you're not familiar with the FAL fans, essentially this switch would have 3 positions. top is constant ON, middle is OFF, and bottom is AUTO where it will come on with the A/C or temp is too high

the thing is, if i wire it this way, it leaves nowhere to ground for the built in LEDS to work. and if i do it how the site says to, it wont work how i need it.

Any suggestions?

Suggestions:
1) Go to Radio Shack and get a switch that's connected internally the way you need. Then see if you can just order the right cover.
2) The switch shown can't be connected, in the configuration you want. IE: When the switch in your diagram in pushed up, from what I can see, the M will connect to 12vdc, yes? And when down, + will connect to 12vcd and C to A/C clutch, yes? If you want LED's, they have to get a ground from someplace. Some switches have a seperate ground lug for the LED's, and switches the hot onto them. The one you've chosen doesn't do that.

Either that, or you'll need two seperate switches. Sorry....

how would i do it with two seperate switches?

*edit*

i guess i'd just get two spdt switches and split up the two sides of my planned diagram. thats not gonna be very convenient though, i'll try to look for a different switch. do you think it'd be possible to switch the covers?

You'll find the right switch easily enough, Just go to Radio Shack, or it's equivalent, and show them the diagram you drew, and tell them how you want it to light up. They'll have the right switch, or be able to get it. You should be able to put the cover on it with no trouble. May take a little "engineering", but I bet you're smart enough to do that :great:

First off, I would just get a normal DDPT switch that makes you happy cosmetically. As you found, the way that switch is designed, it really limits your options unless you start playing with relays and they you're just adding complextity to a really simle circuit.

For the LED(s), do you want to know when the fans are actually running, or when the fan controller has power?

If you want to know when power's applied, then wire an LED across the M and + lead at the switch through a 10k (appx) resistor to ground. You'll need two additional diodes to stop the current flow between the M and + leads as well.
If you want to know when the fans are actually running, then run a line from the hot lead that goes to the fans (after the controller) back into the cab, then on through a 10k resistor, an LED and on to ground.

man those switches are sweet... i assume they fit in the OEM slots?

yeah i measured and they look right on. someone posted that site a while ago and i saved it, i cant remember who it was though

*edit*

found it, it was cebby

https://www.yotatech.com/forums/f2/nice-rocker-switches-57480/

This is my goal, and i know how to do it with a simple LED like you are saying, but i was hoping to make the LEDs the actual rocker light up when the fans are on. I just dont think its going to work how i want it though.

I don't know much about the switches, they look cool though.

One thing though, why go with FAL, they have a bad track record around here. You should try a Taurus fan mod and make it do the same thing FAL can.

yeah i know, i shouldve gone a different way for the fans, but i've had them for a while and since they were so $$ im gonna use them. otherwise, i think the taurus fan or volvo fan is a great idea.

I used a SPDT switch from Radio Shack for my old FAL fan:

http://www.4crawler.com/4x4/CheapTri...tml#FanControl

Thats how i did have it wired up, i just wanted to wire it where the OFF position is truly OFF, even if the A/C is turned on. Thats why i would like a DPDT

Hmmm... Roger's right... you can do this with an SPDT switch.

The A/C input to the fan controller is just a secondary input to the power relay, so if you don't have any power source to the fans, then the A/C input will still trigger the relay in the controller, but it won't cause the fans to run.

alright i'm not understanding this.

how would i wire it using a SPDT switch?

is RBs instructions saying to have a wire from + and B going to each throw, and 12v source going to the pole on the switch? That seems like it would work, but what about terminal M? I thought that needs to be used for a switch....help....


heres what my control box looks like

http://mysite.verizon.net/res7c4ir/controlbox.JPG

I don't have the fan anymore, so don't recall the exact wiring. But what I found was that there was the one connection (I think that is B in your diagram). Hook one pole of the switch to B, the other to M and the center of the switch to 12V. In the B position, you get normal t-stat controlled operation. In the M position, you can always-on, and in the center the fan is off. For the A/C, I simply turned off the A/C if I wanted the fan to be off for sure. I suppose you could run the A/C clutch signal to the second pole on the switch and feed that to the fan in auto-mode.

Since you're basically looking to choose between normal (temp & A/C), always on, or always off, then what about:

ref:
http://mysite.verizon.net/res7c4ir/controlbox.JPG

So, when the switch is connecting:

• 12V --> B, the fan will operate normally. That is, the thermostat will work and if you turn on the AC then that will cause the fans to come on.
• 12V --> B + M, the fan will come on all the time, since you're applying power to the core, and the M lead.
• Center off, the fan will not come on

(This is pretty much what Roger's thinking about)

o man. thats great mark. thanks a lot for the help.

the only thing that im wondering is will the switch be able to handle that? i think the B terminal is supposed to be the higher amp than the + terminal, right? would it work if you did

+
12v
+ & M

or does it have to be B?



one more questions:

i read on some other thread to not use a lighted switch with FAL? is this true? i dont want to ruin the control unit.

Lighted switches (at leas tthe kind internally wired) are not good to use for that application. That is why they need a power and ground connection since they need to supply a connection for the internal light. That is why I used a separate light, tapped off of the motor feed wires, that way I know that the motor is getting power vs. that I just have the switch on. Also the power feed for the fan motor is high current, don't think you would want to be running that through a dash mounted switch. Just do a DPDT:

AC -o o- B
____/ /
C -o o- 12V-fused

n/c-o o- M