i am rewiring a customers car that previously had a VERY bad install. he has door actuators with a push button on the outside. there is a relay installed, but isnt the switch just completing a circuit to energize the actuator? i rewired it that way and it works perfectly. just make sure the relay isn't there for safety reasons. also, we are building custom door panels and want to add a second switch to be able to pop the doors from inside. will i need a relay to accomplish this? thanks
Most relays are used to ensure the switch doesn't receive current over their ratings. Most relays can handle up to 30/40A of current which would be more than enough for a door actuator.
If you were just wiring in a second switch in another location, and the switches you used can handle the task of the actuators w/o the use of a relay, you can wire another switch in parallel with the one you have and it will work the same.
The second switch will wire in parallel across the other switches wires. Basically you are having one or the other switch throw power or ground to the relay to activate it which in turn activates the actuator.
As far as having a second switch inside to pop or open the doors try very hard to add a mechanical handle inside. I redid a 56 Chevy and the upholstery shop added door pop actuators and an inside button but after going over some things with the owner of the car I designed an inside mechanical release. Should you ever be driving down the road or even stopped and there is a major electrical problem on a vehicle equipped with electric door poppers there is no way to get out of it without climbing out the window. Now add in a vehicle with power windows and you are stuck inside.
Below are some links with pictures of the ones I made for the 56. Basically it was an inside hood release handle from a Toyota, some bicycle cables, some cable adjusters to take out slack when the cables stretch from normal use, some pulleys and some fabrication.
https://rides.webshots.com/album/113373496zNgIvF?start=12
https://rides.webshots.com/album/113373496zNgIvF?start=24
Think safety also with the install.
Jim
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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street