Hi. On my truck I have a sports bar with an LED light bar connected to it, attached to a 2” actuator that raises or lowers the light bar depending on the position of the DPDT (on-off-on) switch.
I have no place to mount this switch and was looking for another alternative.
I have a push button control panel in my truck where I can turn on the light bar and other accessories. I wanted to use 2 of the switches on this panel to control the actuator in both directions. The panel consists of latching switches. The accessory turns on when the button is pressed and must be pressed again to turn accessory off.
I know I’m going to need relays in order to accomplish this, however my knowledge in relays is sub-par.
I do not want something that is on-on (so I don’t have to leave the switch on all the time to keep the actuator retracted) and I need a fail-safe incase both buttons are accidentally pushed which would create a short.
If this is possible, could someone please not only explain, what I would need but also provide a wiring diagram explaining which relay terminals go where.
Off the top of my head, I think I need 2 SPDT relays to achieve this but I’m not sure how to prevent the short in the event both buttons are pushed at the same time. Thanks for the help

 

So how does it work with the DPDT switch.
Do you just put it in one of the positions to raise/lower the bar, and then back to off when finished?

If you want it to automatically turn off when the final position is reached, you will either need to add limit-switches to the bar, or perhaps a time-delay to turn off the power after some fixed time.
But it would be difficult to do with two latching buttons (is there an indication as to which position the button is in?).
Easier if the two buttons were momentary.

 

So how does it work with the DPDT switch.
Do you just put it in one of the positions to raise/lower the bar, and then back to off when finished?

If you want it to automatically turn off when the final position is reached, you will either need to add limit-switches to the bar, or perhaps a time-delay to turn off the power after some fixed time.
But it would be difficult to do with two latching buttons (is there an indication as to which position the button is in?).
Easier if the two buttons were momentary.

Yes, one position extends, the other retracts, off in the center. It already turns off when fully extended/retracted.

 

Yes, one position extends, the other retracts, off in the center. It already turns off when fully extended/retracted.

So you don't necessarily need to remove the power after it is extended/retracted(?).

Are the push-buttons SPST (two terminals)?

 

Welcome to AAC.

You said you don’t want to have the switch in the on (depressed) position to retract the light bar, but what about having one button that extends the bar when it is depressed and retracts when it is in the normal (out) position?

This would be the equivalent of the ON-OFF-ON toggle switch except that it would have no idle position—you would either have the bar extended (switch engaged) or retracted (switch released).

Would that work for you? (to me, it seems much more sensible than two latching push buttons that can both be ON at the same time.)

 

So you don't necessarily need to remove the power after it is extended/retracted(?).

Are the push-buttons SPST (two terminals)?

The control panel inside the truck connects to a box under the hood where the positive of each accessory is connceted. Each accessory is grounded separately.

 

Welcome to AAC.

You said you don’t want to have the switch in the on (depressed) position to retract the light bar, but what about having one button that extends the bar when it is depressed and retracts when it is in the normal (out) position?

This would be the equivalent of the ON-OFF-ON toggle switch except that it would have no idle position—you would either have the bar extended (switch engaged) or retracted (switch released).

Would that work for you? (to me, it seems much more sensible than two latching push buttons that can both be ON at the same time.)

Yes, I don’t want an (on-on) solution because the light bar would not be able to be up when there was no power to the truck. I need the flexibility of either having it extended or retracted with or without power.

 

I don’t want an (on-on) solution because the light bar would not be able to be up when there was no power to the truck.

If there's no power than I don't see what difference the connection to the light bar will make(?).
Removing the power would have no effect on the light bar position no matter how it's wired.

So you just wire a DPDT relay in place of the DPDT switch and control the relay with one of the latching PBs.

 

If I wire as you suggested, then when I push in button A, the actuator will extend and the light bar will be up. When I push the button again and turn the switch off, the actuator will retract and the light bar will lower. Is that correct? So isn’t turning truck power off the same as turning off the switch? Which means I cannot have the bar raised when the vehicle is off.
Can’t I achieve what I want by wiring 2 SPDT relays?

 

So isn’t turning truck power off the same as turning off the switch? Which means I cannot have the bar raised when the vehicle is off.

To allow the bar to be up with no power, just power the relay contacts from the truck power switch.
Then when power is removed, even though the relay becomes unpowered, there is no power to lower the bar through the contacts.

Can’t I achieve what I want by wiring 2 SPDT relays?

Yes, but why use two SPDT relays when one DPDT controlled by one switch will do the job?

 

The control panel has push buttons on it. It has no power when the vehicle is off. With the DPDT switch that is currently wired to it, the actuator will stay up even with no power until it is retracted. That is what I am trying to achieve using the buttons

 

To allow the bar to be up with no power, just power the relay contacts from the truck power switch.
Then when power is removed, even though the relay becomes unpowered, there is no power to lower the bar through the contacts.
Yes, but why use two SPDT relays when one DPDT controlled by one switch will do the job?

Because the control panel that I’m using doesn’t have DPDT switches in it

 

Then when power is removed, even though the relay becomes unpowered, there is no power to lower the bar through the contacts.

This is what im not understanding. I thought removing power is what made the actuator retract

 

The control panel has push buttons on it. It has no power when the vehicle is off. With the DPDT switch that is currently wired to it, the actuator will stay up even with no power until it is retracted. That is what I am trying to achieve using the buttons

I understand that.

Because the control panel that I’m using doesn’t have DPDT switches in it

So one switch controls one DPDT relay.

This is what im not understanding. I thought removing power is what made the actuator retract

Then how would the actuator remain up when the truck power is removed?

My assumption (without knowing how it's wired) is that the DPDT switch applies power of one polarity to the motor to raise it, and polarity in the other direction to lower it (similar to the diagram below).
Otherwise you wouldn't need a DPDT contact arrangement.

 

It’s actually the hot and ground that are jumped across with the motor on the center terminals, but yes, that is how it is wired now. It will stay in whatever position it’s in until the switch is engaged in the opposite direction. Using a DPDT relay on a SPST switch is going to need constant power (button engaged) to keep the actuator extended and retract when the button is off. Therefore when I power off truck, actuator will retract. Am I wrong?

 

It’s actually the hot and ground that are jumped across with the motor on the center terminals, but yes, that is how it is wired now

So do you now understand what I have proposed?
The DPDT relay contacts just take the place of the switch DPDT contacts.

 

I understand what you are saying, however I’m not seeing it working it my head.
1. I don’t want to keep the button on to keep the actuator extended
2. I don’t want the actuator to retract when the button is off

 

I understand what you are saying, however I’m not seeing it working it my head.
1. I don’t want to keep the button on to keep the actuator extended
2. I don’t want the actuator to retract when the button is off

Okay.
That's the simplest design and I don't understand why you don't want that, so exactly how do you want the buttons to control the actuator, as I'm not seeing that in my head?
It would seem that using two buttons would lead to confusion.

 

so exactly how do you want the buttons to control the actuator?

The same way the switch is now. I would like to press Button B in the picture and have the actuator extend. Then I can depress the button and have it stay extended. Then push button E and have it retract. Then I can depress the button and have it stay retracted.

 

The same way the switch is now. I would like to press Button B in the picture and have the actuator extend. Then I can depress the button and have it stay extended. Then push button E and have it retract. Then I can depress the button and have it stay retracted.

Okay, but you are missing another scenario,
If both buttons are pressed does the actuator do nothing?