mechanix619

Honda Civic EX '98

I'm getting ready to install a main relay kill layer to my car alarm. I plan to have the alarm control this kill; I know I'll forget to activate a hidden switch just once and presto car stolen. I know what wire to splice, the black ground wire. Does it matter which way the relay faces? Does it matter which end of the black ground wire goes into 87a or 30? Thanks.

I borrowed the picture from the Cause For Alarm website.

http://causeforalarm.thecarthing.com...kill_relay.gif

The picture is for a fuel kill but I am taking the logic for the main relay.

This is what I have thus far:

85 - Alarms ground when armed
86 & 30 - connected
30 - main relay ground wire
87a - main relay ground wire

fcm

That will not work, you have a ground at both #85 and #86.

If your are going to use the alarm to control the PGM-FI Main Relay kill you will need to wire it like this...

#30 - to chassis ground.
#87a- to black ground lead of PGM-FI Main Relay.
#85 - to alarms GWA output, [probably orange lead].
#86 - to "true" ign. source, [hot in run and start].

And if you really want to make noise if someone tries starting the car with the alarm armed, connect #87 to cars horn lead. 94

mechanix619

Right on. Can you explain how the following works?

fcm

The relay is not on the PGM-FI Main Relay ground, it is on the fuel pump power lead, #30 and #86 would have 12V+ when ign. is on and engine running and during priming.

The above kills only the fuel pump power, easily bypassed.

Installing a "kill" relay on the PGM-FI Main Relay ground will cut power to the fuel pump, fuel injectors, ECU and a few engine sensor/valves. 94

mechanix619

I should have worded my question better. I know the picture I posted was for a fuel pump kill. What I would like to know is why the fuel pump kill is wired differently than the main relay. I think I have the basics but I am looking for a better explanation that what I can give. Here's my take, I think they are different because on the fuel pump the kill relay is affecting the power to the pump and on the main relay and kill relay is affecting the ground.


Thanks for the info. I'm wiring up the main relay kill now.

fcm

Actually the only differance is how pins #85 and #86 are wired, they are on either side of the relays coil, [the relays "switch"] and for it to work you need 12V+ on one side and a ground on the other, and it makes no diff. at all if your switching a ground, [PGM-FI Main Relay ground] or 12V+, [power for fuel pump], except if you want to get the power for the relays coil, [#85 or #86] by daisy chaining, [looping] it from the lead you are "killing", that can't be done if your "killing" a ground lead.
The power for the relays coil must by a switched 12V+, either hot in run and start, [true ign.] or hot in start, [starter]. 94

Bad_dude

I know this thread is 3 years old but no point in flooding the forum with another thread.
I have 2 questions:

1) Would you put a diode in between #86 and #85 with the band toward #86?

2) Could I use an Aux to shut off the ground to the main relay by connecting the Aux #85 instead of the orange GWA? I have a Crime Guard 750i6 with feature 23 open with programmable relay built in. How would you wire it? The pages to the manual is below.
Here's SuspendedHatch Main relay kill link http://civic-eg.com/causeforalarm/ma...kill/index.php






Thanks.

wrx-killer-Sti-eater

iTrader: (1)

Wow this thread is old. Bad dude i been watching your post. And if seems that you ask a question and then answer it with a link. Maybe you should take the car somewere and let someone that knows what there doing. Cause you can really mess up your car electrical system. And open up a big can of worms

Bad_dude

Thanks. I was just looking to confirm some of the ideas I had. Like instead of starter kill, I want to install the main relay ground kill but using an Aux to disable the relay instead of automatically. Just some experimental stuffs.
I got the car wires all map out ready for the install. I just want some new fresh ideas with the alarm rather than just some thing that make noise and a starter kill.

I was just wondering of using feature 23 to do the main relay kill when activate the channel. I was trying to see if I can connect the Aux to 87 or 87a to perform this feature?
Thanks.

wrx-killer-Sti-eater

iTrader: (1)

so you lose your remote while out or it falls off your key chain. You then get in the car thru the valet button. Now the car does not start cause you cant use a aux cause you have no remote. Or the remkte break or fails. Keep things simple.

Bad_dude

Thanks. You have a point. What about if I kill the main relay instead of the starter with alarm when trigger?
Thanks.

Axatax

That works fine too, but I agree with advice to keep it simple.

You're already up to three kill relays and five sensors from the looks of your other posts. This will overtax the GWA line and you'll now need yet another relay to provide a higher current ground for all the accessories.

The GWA is usually limited to .5A, and each standard Bosch-type relay consumes roughly 175ma. When you add just a radar sensor into the mix you're right at the limit of of the GWA can handle.

Bad_dude

Let's see now. So far the only relays on the GWA is the starter or main relay kill, window modules, and maybe a voice module later. For other relays, I just have a trunk pop relay which is independent of the GWA wire. For sensors, I got the shock and glass in one on one port and the radar sensor on the 2nd port. The alarm itself has 2 built in programmable relays which so far I am only using one for the horn which I could turn off by valet programming. So I have one more programmable channel open for some thing else but so far I have those 3 wires depin.
As far as tapping into the car wiring, I got both dome and door triggers to one wire; trunk and hood to one wire with diodes isolate band away from brain; I got parking lights to one wire, power I am going run a cable straight from the battery splice it to the brain then further down put the windows modules on it later; door lock and unlock, one plug 2 wires, I am leaving priority unlock off for now since I got to run wires to the door; Ignition power.

That's it simple. Like every thing else when I work on the car is the time to organize the cables for clean looks and convenient of service or addons later.

I ask a lot of questions, first to learn more, to see what I can play with.

Thanks for all of the help and advice guys. Since I am unemployed still, I just want to make use of my time to learn stuffs as I know I will get a job any time and I will never have time to do any thing after that. Just like for 4 years, I got expensive parts waiting in my storage for installation. Boom, unemployed, a little more time but no money. So I sold all of the parts just to survive. Never the less, I am still happy as I am still better off than a lot of other unfortunate people, so I am not going to die complaining.

mechanix619

I'm redoing some alarm wires because of a recent theft attempt. I redid the main relay kill and figured I'd try the #87 to the horn lead. I connected 87 to the gray wire on the 16-pin harness behind the radio (1998 Honda Civic EX) but the horn didn't sound. Am I missing something else? The relay is wired as directed from your original post.

Bjude1

OK you’re going to have a fire! 87 is normally open side of this relay, meaning that it will connect with 30 when the switch is activated. What is "main"? I'm assuming that you are cutting fuel supply relays ground. This would mean that when the system is armed that your horn trigger relay would be connected to the fuel pump ground output?

What are you trying to do?

nsxxtreme

Its a trade off do you want an active or passive kill? One is more secure then the other but you are giving up convienence.

The downside of of active kills is they require the alarm be operational for them to work.
There are many ways to "take out" an alarm no matter how well hidden you "THINK" it is.
Take out the alarm the kill goes away and you can now start the car.

Passive kills work wether the alarm is connected or not. In other words the alarm needs to functioning for the car to start. The downside is if something goes wrong with the alarm or the relay goes bad your car is stuck.

You have to decide which you want and what your willing to put up with.

mechanix619

I'm trying to accomplish what FCM suggested.

Bjude1

Most alarm systems come with a horn output that can be used for this purpose during a full trigger. If it dosn't then you can put a light flasher on the siren output. Besides, this would only function if someone turned on the ignition. You want it to draw attention to your car during a break in.
At the end of the day if someone wants to steal your car, all they have to do is call a tow truck and tow it away to where ever they want so don’t try and re-invent the car alarm. You will regret it when the system fails and its pouring down rain outside.

mechanix619

Please explain, besides wiring the horn to #87 what is wrong?

Bjude1

Cutting the fuel supply is just not a good idea. There is a reason why all alarm manufactures give you a starter kill relay with the box. It’s safe. If the relay were to ever fail while driving, you would lose power everything, brakes, steering and engine. Think if you are driving down the highway at a high speed when that happened.
It all goes back to the point that I made. If someone is going to steal it, they can. Make your car obnoxious and loud if the car is broken into. If the thief is going to tear out the ignition then they are going to pull the plastic knee panel down and defeat the security system.

If you want a badass starter disable then add the starter kill relay under the hood next to the starter and install the brain under the glove box and add a backup battery to keep the relay engaged.

mechanix619

Ah, now we're getting somewhere. There isn't anything wrong the how the relay is installed, you're just not a fan of that particular type of kill.

Cutting the Main-Relay and/or ECU is the best kill for a Honda in my opinion.

I get what you're saying though, if someone wants the car they are just going to tow it but for maybe 75% of the people that are going to break into a Honda they won't have a tow truck so making the car not start is primary. A tow truck is really for vehicles that are left outside over night, my vehicle stays in the garage. I'm primarily concerned about protecting the car when I'm out at dinner or a movie. A thief is unlikely, though its possible, to roll-up to a restaurant or movie theater with a tow truck and steal my car. A starter kill can be bypassed regardless of where its installed. A Main-Relay and ECU kill can't be easily bypassed if hidden ect. If my car is left unattended for a few hours my primary goal is to make it impossible for a thief to drive away.

I've had the Main-Relay kill installed for over four years with no issues. I was just trying to test FCM's suggestion about adding the horn to pin 87.

nsxxtreme

That's a myth. I could bypass it easily.
Has someone tried to actually steal your car and not just break in?
Unfortunately judging any security on the fact your car hasn't been stolen is a worthless game.

Don't get me wrong I fully support making it as difficult as possible. I however would not depend on a single kill to protect yourself. A main relay is a single kill contrary to the claims made on this site. If you're a 1/2 intelligent theif you could bypass this kill with two jumper wires no matter where you hide the relay. I suspect as this becomes more popular and cars start getting stolen people will catch on.

Protect yourself with multiple layers of security. The same rules that always existed still exist The install is 90% of the security.

mechanix619

*sigh*

This is the problem with this forum, and many others, people come in and give their opinions without actually addressing the question(s) asked.

I get what you are saying, and agree, but based on the text you decided to quote from my previous post you didn't actually address what I posted.

I was commenting on Bjude1 earlier post, regarding the main relay kill being safe/dependable or not. As I stated, I've had it installed for years with zero issues; zero issues meaning the kill has not left me stranded because it failed. Also, I would rather be stranded one day in the pouring rain versus having sub-par security.

I appreciate a good opinion as well as the next guy but no one has actually answer the question at hand, or even attempted to answer the question.

I have multiple layers of security. As I stated in my post, someone attempted to steal the car but they failed; they made a mess of the wires in the progress, which is why I was going through re-doing everything.

Yes, it is possible to find and disable the main-relay kill, or any other kill, but I'm pretty sure everyone is aware that there isn't one magic kill; so this isn't news to anyone.


EDIT

I take part of my statement back. I see you did comment directly on something I said. I said the main relay can't be easily bypassed to which you responded.

I don't have the main relay out in the open with a big neon sign pointing to it saying "HERE I AM." But yes, if a thief has the time they can dig and find its location. Again, the point is to slow a thief down and make as much noise as possible; hence my original question about adding the cars horn wire to pin 87 of the main relay kill relay.

nsxxtreme

Works for an automatic fails for a stick. And any who ha that has worked on a car before knows how to bump the starter. Hell they even sell switches with long wires and alligator clips at the part store for this specific task.

nsxxtreme

Since the purpose of this relay is to shut down the fuel pump and fuel injectors in the event of an accident its a very reliable kill. Although alot of Honda's have issues with the main relay when they get older, that's a different topic. So it's no less reliable then how it functions to begin with. Your main relay will likely leave you stranded in the future but that has nothing to do with this kill. Although it might make it more difficult to diagnose the problem.
You dont need to find the relay which is what I was trying to point out without giving specific details. It's not as secure as some would make it out to be. The main relay cuts power to the fuel pump and fuel injectors that's it. In no way does it prevent the ECU from working. IMO it's only slightly more secure then a standard fuel pump kill and that's just because it's not as well known.

It's good you have other kills that is the way it should be.

I don't know what the question is you had. It seems to me you already had your question answered.

If I remember correctly they are cutting the groung of the main relay. Assuming your horn is a - pulsed horn there is no reason you couldn't drive it from the extra relay. Keep in mind your horn will be on for one giant whale and will drain the battery faster.