Calling Electrical Guru's

I'm adding all new work lights to my Case 1190 and need some help identifying a relay...I know what I want, but I don't know the proper terminology to find one. I currently have a relay similar to the one pictured but once the coil is activated, the relay doesn't deactivate until the whole thing is powered down.

The light switch has 3 positions and I have it wired up so that the front lights are on when the switch is in the 1st position. When its in the 2nd position the front and rear lights are on and when the switch is in the 3rd position, the front, rear and front "brights" are all on. The relay works great turning them on, but they don't shut down in the same manner. When you shut them down, you turn the knob back down to the 2nd position, everything stays on until you turn the knob all the way back down to the 1st position which then turns off both the brights and the rear work lights. It's not a major problem by any means but I would like it work like your normal tractor lights.

I'm looking for a relay that deactivates when the coil is deactivated, what would be the proper terminology for one of these, if it is possible?

Thank you,

carpetfarmer
 
Some things to search the 'net for... "automotive ice cube relay" or "Bosch Relay" or "Hella Relay".

Most will be "SPDT", meaning the incoming power is switched to one terminal when the relay is deactivated and another when it is activated, so by NOT using the terminal I mentioned first the relay will do what you need.
 
Sorry, I forgot to add the picture in the original post.
a196629.jpg
 
I may be misunderstanding but thats what I have now, a single pole double throw, but the contacts don't switch back to their normal position when the coil is deactivated. They only return to their normal position when the entire relay is powered down.
 
You must have a cross-connection between the coil terminals (85 and 86) and the N.O. power terminals (30 and 87) you need for carrying the load current?
 
The relay you show will not work for the three different setting of the lights only using one relay. Terminal 85 is to energize the relay only and terminal 86 should be grounded. When the relay is not energized (no power to 85) power flows from terminal 30 to 87A. When the relay is energized (power to 85) power flow from terminal 30 is switched from 87A to 87. Power to terminal 30 should be a fused hotwire. Power will not return to terminal 87A until power is dropped from terminal 85. To achieve what you need for the three different positions on the switch you should use three different relays like the one you show. This of course all depends on how the contacts in your three position switch are arranged and how power is routed through the switch. If you are using the relay to power only extra added lights then find the terminal on the light switch that becomes hot when the switch is in the position you desire 1,2 or 3 and power terminal 85 on your relay from that point. You will also need to run a fused hot wire to terminal 30 and from terminal 87 to your extra lights. Terminal 87A is not used. I know this is about as clear as mud but maybe it will help. Dennis
 
Dennis,

Your explanation is totally correct and clear. There is no way that one relay will do what is wanted so as you say three relays are needed.

(From an older, retired electronics engineer and maybe a bit rusty!!)

Ron
 
Whatever relay you are currently using can't possibly work as you say all by itself. There has to be some other wiring not connected via the relay that is turning on and off some of the lights.

Or else your description here isn't telling the whole story.

Ron (retired electronics engineer)
 
No worries, its rather hard to explain without visuals. I will try to explain better, but will probably only make the water muddier.

The light switch I have has 3 positions and thus 3 outgoing terminals, the following is the knob position followed by activated outgoing terminals:
Position 1 - Hot Terminal: 1
Position 2 - Hot Terminal: 1 & 2
Position 3 - Hot Terminal: 1 & 3

End Goal: Position 3 - Hot Terminal: 1 & 3 + 2

For the problem at hand Position/Terminal 1 is irrelevant, so we can forget about it...from now on it's non existent.

Since pictures are worth a thousand words, here is a drawing of how I have it wired now. Note that I have tried running a hot wire directly to terminal 30 with no change in operation...aka, relay doesn't return to normal position until power is removed from terminal 30.
a196685.jpg
 
You're back feeding the relay.
I'm not entirely clear what the
end goal is (not quite up to
speed this AM) - 1&3+2-,but what you have drawn
is back (cross) fed.
 
After looking at your second post you should get the desired results by wiring your lights as showed, using only the one relay you have. I did not show it in the drawing, but the hotwire to the switch should be fused. As you can see I am no artist but maybe it will help you out. Make sure your switch will carry the amp load that is required for your lights. Dennis
a196718.jpg
 
Thank you all for your help, and Dennis, thank you for the illustration.

I'm using a repop stock light switch, with power coming into it via the fuse panel (currently 15A fuse), and I am running 2x 48W LED work lights for the low beams, 2x LED work lights for the rear work lights and 1x 120W LED lightbar for the front end high beams. Shouldn't be overloading the system by any means considering it had all incandescents originally.

Please pardon my ignorance here Dennis, but short of yours being drawn using proper electrical schematic symbols, what is the difference between your circuit and the one I drew?
 
This still won't do what is wanted based on what I see in the drawing. Why does switch positon 2 show termnal 1 and 2 connected? Why does switch position 3 show terminal 1 and 3 connected? A full explanation of how the switch works in each position is needed to totally understand how to get the wiring correct.
 
Your drawing is basically the same as mine except for the lines showing the circuit for position 1. Your relay cannot be operating correctly the only way the bright lights can stay on after returning the switch to position 2 is for current to back feed through terminal 87 from terminal 2 on the switch to 30 and then back to terminal 3 on the switch. When the switch is returned to position 2 all power should be dropped from terminal 86 which in turn should open the circuit between 87 and 30. One thing that may be happening is that both terminal 2 and 3 on the switch are powered at the same time when changing positions between 2 and 3. You would not see anything out of the normal when going from 2 to 3, but when going back from 3 to 2. This would cause the relay to seal itself into the energized state making the bright lights stay on until power is dropped from terminal 2 on the switch or the switch is returned to position 1. I hope I have not made things more confusing. I sometimes have to stop and think about what I am trying to say because I confuse myself. Dennis
 

Your posting was timely for me since I am planning a similar tractor light installation project. I have used these relays in the past for various applications however, I have never used one to add an extra function to a switch.

I have attached two circuit diagrams, one using the relay and another using a diode. I have not actually verified function however, I believe they will do what you are trying to accomplish.

I plan to use a diode for my installation however since you have the relay I am sure you will want to use it.

If anyone finds a problem - comments are welcome.
24960.jpg
24961.jpg
 
I'm not going to have time to check into it deeper for a week or two, but your hypothesis about not losing continuity between the steps in the switch makes sense; that's kind of what I was wondering about the contacts sealing themselves in the energized state but didn't know how to put it in words...it made sense in my head though...happens a lot...
 
My first thought before using a relay was to use a diode, just for simplicity but I didn't know if you could get one that would
work. How would you go about sizing one, or how would you figure out what size you would need and then where would you get one
and how would you physically wire it into the circuit? The only diodes I've ever seen were for use in computer circuit boards and
not automotive applications per say.
 
(quoted from post at 18:08:01 07/27/15) My first thought before using a relay was to use a diode, just for simplicity but I didn't know if you could get one that would
work. How would you go about sizing one, or how would you figure out what size you would need and then where would you get one
and how would you physically wire it into the circuit? The only diodes I've ever seen were for use in computer circuit boards and
not automotive applications per say.

Diode sizing is based on current, in amps. The diode supplys power to both rear work lights therefore, you need to add the amps of each light. It should state on the package the amps used by each light.

Radio Shack is one place to buy diodes. For example, P/N 276-1661 is for a 6 amp diode, with a Vr of 35 volts. The Vr is the reverse voltage that the diode needs to block - in this case it is 12 volts.

The diode is connected across terminal 2 and terminal 3 of the switch such that power flows from terminal 3 to 2 and powers the rear work lights. The diode does not conduct (blocks current flow) in the reverse direction. The diode is marked with a white band (-) which goes to the load, terminal 2. The unmarked end is (+) and goes to terminal 3. Note, if your tractor is positive ground then reverse the connection.

The other switch connections are as follows:

Terminal 1 to the front LB
Terminal 2 to the rear work lights
Terminal 3 to the front HB

I see the scans had problems making the trip. I could trace the lines with black ink and re-send, if they are of value to
someone. In the event you decide to go with the relay; terminal 85 is wired to only receive power from terminal 3 of the switch. This prevents the "latching" you observed.
 
I will continue to do some more fiddling with the relay when I get a chance and see if I can get it to work as desired but I may
pick up a diode also. How would you attach it to the circuit? can you put a spade connector on a diode or do you have to solder
it or how do you make the actual connection?

Thank you everyone again for all your help!
 
(quoted from post at 19:11:19 07/28/15) I will continue to do some more fiddling with the relay when I get a chance and see if I can get it to work as desired but I may
pick up a diode also. How would you attach it to the circuit? can you put a spade connector on a diode or do you have to solder
it or how do you make the actual connection?

Thank you everyone again for all your help!

The diode leads will be solid wire rather than stranded, so simply crimping a spade connector on will not/may not stay tight. The diode is connected across terminals 2 and 3 of the switch. I believe you could include the diode lead along with the stranded wire when you crimp the spade terminals for these connections. The diode leads should be long enough to reach the two switch terminals. The leads can also be soldered - you will not damage the diode unless you get crazy with the heat.

Another option would be to buy a Full-Wave Bridge Rectifier with male spade terminals. These have four diodes inside and will have 4 terminals. You will only use two of the four terminals. For negetive ground, connect the (+) terminal to terminal (2) of the switch and the (AC) terminal to terminal (3) of the switch. Note, since there are four diodes there is more than one connection that will work.

These are available at Radio Shack, for example P/N 276-1185 is a 25 amp and 50 volt (reverse volts).
 

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