external trunk release button
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=96112
Printed Date: May 13, 2025 at 12:21 PM
Topic: external trunk release button
Posted By: danlong
Subject: external trunk release button
Date Posted: August 02, 2007 at 1:24 AM
I want to add a button to activate the trunk solenoid right above my license plate where it can't be seen, but I need a way to disable it when I lock the doors to keep the trunk secure. I have a button in the car, I just want the convenience like many high end cars have. Any modules available to do this, or could it possibly be done with relays or such? Car is a 2005 Mazda 6 sedan.
Replies:
Posted By: howie ll
Date Posted: August 02, 2007 at 1:15 PM
Assuming factory switch is low current operating a remotely located relay as in Toota, European Ford or US Focus, use a latching relay controlled by the door locks, either trigger or motor going to break feed from switch. this will not draw any juice.
Posted By: peterubers
Date Posted: August 05, 2007 at 1:39 PM
yeah, agreed -- you'll need to tap into the mazda's lock/unlock wires and setup the latching relay (closes circuit when unlocked to allow external button to open trunk, and then opens circuit to prevent this from occuring when car is locked) | Power Unlock | | BLUE OR GREEN | | (-) | | FACTORY KEYLESS MODULE | |  |  | PowerLock | | SAME WIRE | | (-) | | FACTORY KEYLESS MODULE |
USE A 1000 OHM RESISTOR TO LOCK AND STRAIGHT GROUND TO UNLOCK. MUST USE RELAYS TO ISOLATE AND BOOST SIGNAL. Usually there are only two wires behind the cabin trunk pop button -- one is ground, the other goes to the trunk popper at the trunk -- ------------- The search function is your friend.
Posted By: danlong
Date Posted: August 05, 2007 at 9:53 PM
How does that resistor affect the signal? I need to differentiate between the lock and unlock pulse to latch or "unlatch" the relay. With a two wire setup this would be easy, but I'm not sure about the single wire setup.
Posted By: peterubers
Date Posted: August 05, 2007 at 10:23 PM
in that case you may have to use the motor + wire to latch/unlatch (motor = actuator)
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The search function is your friend.
Posted By: danlong
Date Posted: August 05, 2007 at 10:28 PM
That's what I was thinking, do you know of a good source for the latching relays? I understand them, but have never used one before or even looked to purchase one. Thanks!
Posted By: peterubers
Date Posted: August 05, 2007 at 10:47 PM
https://www.the12volt.com/relays/page5.asp#lsp------------- The search function is your friend.
Posted By: danlong
Date Posted: August 06, 2007 at 10:37 AM
That will work, but they make some with 2 inputs, one to latch and one to unlatch. The problem with the one you can build is that if the lock button gets hit twice, it will flip back to the unlocked state.
Posted By: peterubers
Date Posted: August 06, 2007 at 4:22 PM
Alternate is then just to do it off the dome light -- when the dome is on, trunk will be able to be popped by ext. button. Use the dome light output wire from the BECU (body elec. control unit) so that even if you accidentally leave the dome light on by the switch, the trunk won't be poppable by ext. switch. ------------- The search function is your friend.
Posted By: howie ll
Date Posted: August 07, 2007 at 1:07 PM
One ground to latching relay is from lock wire, ground from unlock wire triggers an open circuit! Or vice versa. Latching reays normally come with 2x 12v+ feeds, 2 x ground feeds and either 2 x open or 1x open and 1 xclosed ore a changeover circuit. You can either constantly live and neg switch or if you are using motor wires, constantly neg and 12v+ switch! bSee what the relay does!
Posted By: howie ll
Date Posted: August 07, 2007 at 1:10 PM
Sorry if my last post was a little vague but the last time I configured this was a G4 Clifford Solaris with only one aux output, I configured the latch to give me one output when armed via a 20sec timer for h/lights and a 1 sec pulse when disarmed to give me trunk release. This was about 13 years ago!
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