Installing a power lock in the tailgate

jscherb

TJ Enthusiast
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Elmira, NY
Back when I built the Safari Cab hardtop and barn door for the LJ, I installed a power lock actuator in the tailgate so I could lock/unlock it from the driver's seat. That actuator seems to have lost strength and sometimes can't unlock the tailgate so yesterday I replaced it with a new one. I took a photo while I was replacing the actuator and in case anyone else is interested in installing a power lock in their tailgate I'll document what's involved. This is the new actuator I installed.

NewLockActuator.jpg


I picked up the door lock actuator on a trip to Florida last month at one of my favorite electronics surplus stores (Skycraft Surplus (https://skycraftsurplus.com/). This particular actuator is available on Amazon for about $30 but it was about $10 in the surplus store.

The lock actuator is thin enough to slip inside the tailgate. The yellow dashed line shows where the body of the actuator is, some of it is out of the frame of this photo. The green circles show the screw heads that attach the actuator to the inside of the tailgate (I drilled holes years ago for the original actuator). The orange line shows the rod from the actuator to the lock rod (it's behind some of the latch mechanism so I drew it in for clarity).

LockActuator.jpg


I put the wiring for the power lock in back in 2010 when I built the barn door so all of the following images show work I did back then.

Rather than have wires to power the actuator draped from the body to the tailgate, I added a second pair of taiglate contacts:

LockActuatorPower.jpg


I pulled a lock switch from some Ford vehicle at the u-pull and mounted it on the panel below the steering wheel. Also added the USB outlet below the switch, although that was later - about 5 years ago. The outlet allows me to charge my phone in it's suction cup holder on the windshield with a very short wire - not a long wire draped all over the interior.

LockActuatorSwitch.jpg


These lock actuators are two-wire devices and the power needs to be reversed to lock vs. unlock. The Ford switch is an SPDT switch, so to make the actuator work properly it provides momentary contact power to one of two relays which send the appropriate polarity voltage to the lock actuator. The circuit is pretty simple - 12v is always routed to both sides of the actuator through the normally closed contacts of both relays. When the lock or unlock switch is pressed, the appropriate relay switches that side of the actuator to ground, completing the circuit to operate the actuator. I mounted these relays under the dash.

PowerLockWiring.jpg


If you want to wire a lock actuator without relays, you can use a double-pole, double-throw momentary switch like this:

PowerLockWiringSimple.jpg


I took the slightly more complex route with relays because I wanted an OEM-looking switch that would install nicely somewhere in the LJ's dash and the best one I could find in the u-pull was the Ford one in the photo in my last posts. It's a single-pole double-throw momentary so it can't be wired to reverse polarity without the relays.

Over the years it's been very handy to be able to lock or unlock the tailgate from the driver's seat, and I've missed that capability since the original actuator failed. It's nice to have this feature back.
 
Actuators were one of my first mods to both doors and the tailgate, well worth it. I actuate mine with a remote.
 
That's a very clever circuit with the relays. I would have ended up with something more complicated. The switch is the classic method.
 
Back when I built the Safari Cab hardtop and barn door for the LJ, I installed a power lock actuator in the tailgate so I could lock/unlock it from the driver's seat. That actuator seems to have lost strength and sometimes can't unlock the tailgate so yesterday I replaced it with a new one. I took a photo while I was replacing the actuator and in case anyone else is interested in installing a power lock in their tailgate I'll document what's involved. This is the new actuator I installed.

View attachment 294071

I picked up the door lock actuator on a trip to Florida last month at one of my favorite electronics surplus stores (Skycraft Surplus (https://skycraftsurplus.com/). This particular actuator is available on Amazon for about $30 but it was about $10 in the surplus store.

The lock actuator is thin enough to slip inside the tailgate. The yellow dashed line shows where the body of the actuator is, some of it is out of the frame of this photo. The green circles show the screw heads that attach the actuator to the inside of the tailgate (I drilled holes years ago for the original actuator). The orange line shows the rod from the actuator to the lock rod (it's behind some of the latch mechanism so I drew it in for clarity).

View attachment 294072

I put the wiring for the power lock in back in 2010 when I built the barn door so all of the following images show work I did back then.

Rather than have wires to power the actuator draped from the body to the tailgate, I added a second pair of taiglate contacts:

View attachment 294073

I pulled a lock switch from some Ford vehicle at the u-pull and mounted it on the panel below the steering wheel. Also added the USB outlet below the switch, although that was later - about 5 years ago. The outlet allows me to charge my phone in it's suction cup holder on the windshield with a very short wire - not a long wire draped all over the interior.

View attachment 294074

These lock actuators are two-wire devices and the power needs to be reversed to lock vs. unlock. The Ford switch is an SPDT switch, so to make the actuator work properly it provides momentary contact power to one of two relays which send the appropriate polarity voltage to the lock actuator. The circuit is pretty simple - 12v is always routed to both sides of the actuator through the normally closed contacts of both relays. When the lock or unlock switch is pressed, the appropriate relay switches that side of the actuator to ground, completing the circuit to operate the actuator. I mounted these relays under the dash.

View attachment 294075

If you want to wire a lock actuator without relays, you can use a double-pole, double-throw momentary switch like this:

View attachment 294076

I took the slightly more complex route with relays because I wanted an OEM-looking switch that would install nicely somewhere in the LJ's dash and the best one I could find in the u-pull was the Ford one in the photo in my last posts. It's a single-pole double-throw momentary so it can't be wired to reverse polarity without the relays.

Over the years it's been very handy to be able to lock or unlock the tailgate from the driver's seat, and I've missed that capability since the original actuator failed. It's nice to have this feature back.
Very cool upgrade! And judging by your schematics and your ingenuity, I’ve got a small project for you…

My 05 LJ has the automatic tranny that reqires me to switch the overdrive to “off” every time I get in it to drive. I wish there was a way to redesign the electronics to be opposite; direct drive by default, overdrive when selected. I’m thinking you’re my guy! 👊😎 And you could sell millions of these!
 
Very cool upgrade! And judging by your schematics and your ingenuity, I’ve got a small project for you…

My 05 LJ has the automatic tranny that reqires me to switch the overdrive to “off” every time I get in it to drive. I wish there was a way to redesign the electronics to be opposite; direct drive by default, overdrive when selected. I’m thinking you’re my guy! 👊😎 And you could sell millions of these!
The thread to that is in the how to section- all it takes is a relay and some wire.

jscherb would do it brilliantly- he is so impressive.

F5630911-74A7-4FCD-9E4C-E6AF5C48F9C9.png
 
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Awesome! Thanks buddy, I hadn’t seen that yet.
I loved it in my auto - some mustang guys worked it out I believe and me and @Jamison C borrowed the idea. It isn’t hard, just pulses the reverse light circuit as you shift to drive and that signal turns it off via the relay and it stays off til the next time you start it.