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I am trying to get a tailgate release button to work on my pickup truck. The problem I have is the switch burnt out. Am I running too much current through it?

I have attached a picture of what my setup is. Do I need to add a relay for the switch? If I do the relay, will there be any load on the switch that could cause it to burn up again or do I have to add a resistor or something to help?

enter image description here

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    \$\begingroup\$ If you're using something like a pop and lock with a solenoid coil, you might need to put a snubber in there to prevent arcing at the contacts. \$\endgroup\$
    – vir
    Oct 27, 2022 at 18:04
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    \$\begingroup\$ The #1 reason for failure is using cheap overseas garbage off Aliexpres/eBay/Amazon/wish.com, which is fine for tinkertoy bench experiments but unfit for the real world. The #2 reason is using a UR-Recognized switch but not reading the switch spec sheet esp. regarding interruption of inductive loads. You can certainly buy switches up to the task and I see no need for a relay. \$\endgroup\$ Oct 27, 2022 at 23:48

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The switch needs to be rated for the voltage and current AND type of current (AC or DC) of your load. And if it's illuminated or has 3 or more pins, wired correctly.

Since you say it works for a while then slowly stops, it's likely the switch is not rated for the current, or for DC, and the solenoid is causing the switch contacts to get corroded on opening causing worse performance.

No, a resistor is not needed here. The switch needs to be atleast 12 V DC but should be more like 15 V or higher since an average car system is 14.5 V while the car is on and the alternator is running. But 12 V is nominal.

Yes, a relay is likely needed. At 7+ A, you won't find many switches at the auto shop that will handle it directly.

A common 10 to 20 Amp auto relay should be wired in between. 20 A is better to account for stall current. And an appropriate sized fuse should be inline somewhere. A 7 A solenoid can stall at a much higher fire-causing amperage.

Basic wiring:

source: https://www.wj-99.top/ProductDetail.aspx?iid=155776829&pr=32.96

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    \$\begingroup\$ Thanks for the comments. I am using all GM Oem parts which is why I can't find any information on what everything is rated at. I have installed a relay and tried the switch about 50 times now and it seems to be okay. I do have a fuse but i had to guess at 7.5 amps. I might keep stepping the fuse size down until it blows to try and figure out the rating. Any way that I can figure out how many amps I need to fuse the lock actuator at? I guess only time will tell if it burns up again. \$\endgroup\$ Oct 28, 2022 at 11:33
  • \$\begingroup\$ A ammeter or multimeter with a holding feature would tell you the largest current it can sense. But if you are using oem parts, find the wiring diagram of a car that uses that solenoid and then use the fuse that car uses for that circuit. It would be a safe bet. \$\endgroup\$
    – Passerby
    Oct 29, 2022 at 1:14
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So use the switch to operate a relay that controls the lock actuator.

Be a good idea to add a fuse to the circuit.

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