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Discussion Starter · #1 · (Edited)
This is for a 2015 LX Coupe. As I've posted in another thread, I have been working on an alarm and remote effects project, and I am thinking of how I can integrate the aftermarket alarm with the factory one. For the plan I am considering, I would like to use the motor/actuator wires for the driver's door lock as triggers -- I'll explain more in a bit.

Now, keep in mind, I'm not talking about the low-current triggers for the factory locks coming from the door switches -- I'm talking about the output of the factory relays that actually powers the lock motor/actuator. One source I found says these wires are blue and yellow in the driver's kick panel, but I would like to verify that before I start probing around.

The reason I want to use these wires is because I want something that can handle higher current when the doors are locked and unlocked with the factory key-fob remote, so I figure that if these wires are driving a lock motor/actuator, then I should be able to hook up small relays to them.

My general plan -- and I know this sounds nuts -- is to have one of the remotes to my aftermarket alarm mounted in the car with a couple small relays wired to the arm and disarm contacts of the remote. The idea is that when I lock the door with the factory key-fob remote, then the lock motor wire will trip the relay to short the contacts to activate the arm function of the aftermarket alarm remote, and then when I unlock the door with the factory key-fob remote, then the unlock motor wire will trip the relay to short the contacts to activate the disarm function of the aftermarket alarm remote. If this works the way I think it will, then it will allow both alarms (factory and aftermarket) to be armed and disarmed with the factory key-fob remote without too much hacking into the car's wiring.

Of course, this means that the aftermarket alarm would arm anytime the doors are electrically locked, but I don't think the aftermarket alarm will actually arm when the key is on, even if I try to arm it with the remote, so this shouldn't be a problem. However, I have to test this. Additionally, the other concern is that I would have to occasionally change the battery for the aftermarket remote mounted inside the car, but those batteries usually last a long time.

So, if anyone has any verification or information about the driver's door lock motor/actuator wires, I would appreciate any information you can provide.
 

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Sounds like an interesting project. Unfortunately, I can't find my OEM in-car wiring diagrams. All I can find are the diagrams from the ECM.

If no one here with ServiceExpress access can give you the verified OEM wiring diagram, I would purchase the 1 day access and download/print out as many of them as you can. Sounds like it might come in handy for any future projects as well.
 

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Discussion Starter · #3 ·
Okay, thanks for the suggestion. I may end up doing just that -- paying for the one day access to ServiceExpress -- to get the wiring diagrams that I need. I've never used that service before. I take it that it is a legitimate company that hasn't given anyone here any trouble concerning credit card issues or anything like that?
 

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It's Honda's official source for troubleshooting and technical documents for shops (And for those doing their own work obviously). So you get the stuff the dealers have access to.

It's a great resource. Like I said, I would look up as much stuff as you can and take full advantage.
 

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Discussion Starter · #5 · (Edited)
Well, an update to the project...

But first, as this gets into more detail, a DISCLAIMER: If you use any of the information I have provided, please understand that that this information is provided "as-is" with no warranty of any kind, and any work you do to your vehicle is purely "at your own risk". YOU ARE SOLELY RESPONSIBLE FOR THE RESULTS OF ANY WORK THAT YOU DO TO YOUR CAR. If you are at all uncomfortable or inexperienced working on vehicles (especially electronics and mechanical), please reconsider doing the job yourself. It is possible on any project to damage your car, void your factory warranty, disable a safety feature, create a hazardous condition, or harm or even kill yourself or others. Examples would be the vehicle failing on you, getting an electric shock, or disabling an airbag etc.

(note that I copied part of that from another thread)

So...

I haven't yet continued searching for the lock wires. But I have done some more work on the project. I tested the aftermarket alarm, and it does not appear to be able to arm while it is powered up with the car on, which is good and what I expected. I also realized that having two remotes triggering two separate alarms at the same time might cause one to jam the other, so I tested that -- pushed the arm/lock buttons on both the factory key-fob remote and my aftermarket alarm remote, and did the same thing for disarm/unlock -- and they both worked together fine. So, maybe they are on different frequencies.

Another thing I did was implement an also-wacky door trigger. As some of you may know by some of my other posts, I am quite "anal" about tapping into wires in this car, as it is essentially a collection of computers with an engine on wheels, and the last thing I want to do is fry a thousand dollar computer brain due to some screw-up I might inadvertently do with my wiring. So, for a door trigger, I could've easily found a regular door trigger wire and tapped into it, but I wanted to avoid that. So, I mounted a photocell by the light bulb of the dome light that comes on when the door opens. Since I have already mounted an overhead control console up there and ran wires up there, this was no big deal (in fact, when running wires up there 3 years ago after I got the car, I knew it was a bit of pain to do -- you have to take into account the side curtain airbags -- so I ran some extra wires at the same time for future projects like this). One lead of the photocell goes to ground, the other lead is the trigger wire -- when the dome light comes on and illuminates the photocell, the photocell sends the ground to the trigger wire.

Now, simply hooking this trigger wire from the photocell to the alarm's door trigger wire worked fine -- but I wanted to do more with it. I wanted to add some LED floor lights for a "luxury touch" that illuminates the foot wells when opening the door. The photocell seemed to be providing too much resistance to the LED strips I'm using, so they didn't get very bright when I had them hooked directly to the photocell's trigger wire. So, I built a small relay assembly to allow the photocell's trigger wire to trip that relay, which then sends a solid ground to both the alarm's door trigger wire and the LED floor lights, and it all works fine. Any time the the dome light is on, the floor lights also come on, without any direct connection to the door pin or dome light circuitry. The only drawback that I can see is that if the bulb for the dome light burns out, or if the switch for the dome light is switched to full-off, then this will not work.

There's even more to that relay assembly involving details that I won't get into at this point -- but essentially, one of my concerns with relays (in such a computer-based car) is that, when a relay de-energizes, the coil can send a high-voltage spike back through the wires that feed to it, so my concern is that this spike could get to a car computer and damage it. Well, I used a collection of diodes, a resistor, and a capacitor to help prevent the spike from occurring and to "quench" or dissipate it if it does occur. Additionally, this is a low-current relay that likely does not produce too much of a voltage spike, anyway -- but I am not totally sure.

My only other concern at this point was how the dome light comes on when disarming the factory alarm. I was concerned that, when using both the factory key-fob remote and the aftermarket alarm remote to disarm both alarms (factory and aftermarket), would there be a moment where the aftermarket alarm was still alarmed and then triggered by the dome light coming on? This does not seem to be the case. After disarming the aftermarket alarm, its LED will blink in certain patterns to indicate if something triggered it while it was armed. A repeating pattern of 3 blinks indicates that the door wire was triggered. Well, after arming both alarms, when I went to disarm them, even when I purposely disarmed the aftermarket alarm a fraction of a second after the factory alarm, there was no repeating blinking pattern on the aftermarket alarm's LED, which means it did not sense the door trigger setting it off -- even for a moment -- when disarming the alarms.

So, everything seems to be a "go" for continuing with this project, so far!
 
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