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connecting keyfob to a relay

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=126152
Printed Date: March 29, 2024 at 9:45 AM


Topic: connecting keyfob to a relay

Posted By: scottdw
Subject: connecting keyfob to a relay
Date Posted: February 14, 2011 at 9:10 AM

I am trying to connect my remote start keyfob to a relay to basically be able to remote start my car thru a cell phone. It's an Avital remote starter, 4100 I think. I am following what was posted on this site:
https://sites.google.com/site/vehicleremotestarterextender/

using this device:
GSM-Auto

I am not sure how to connect this to the keyfob though.
According to the diagram:

posted_image

I would connect my keyfob's remote start button to 3 and 5 and I assume I would follow the traces to the correct points on the board of the keyfob.
Here is a fairly high-res photo of the keyfob:

Keyfob

The remote start button is SW4 which is the snowflake on the button.

Can anyone help me out.

Thanks in advance.

Scott



Replies:

Posted By: KPierson
Date Posted: February 14, 2011 at 11:51 AM
I'm not sure what the question here is - it sounds like you have it all figured out. There is a nice solder spot for one side of the button but the other side is a small via that will be harder to interface with.

One other thing I would suggest is to replace the battery in the transmitter with a power supply connected to constant power - this way the fob will never die!

-------------
Kevin Pierson




Posted By: awdeclipse
Date Posted: February 14, 2011 at 1:13 PM
Why hack up the FOB. Doesn't that module have the "Activation Input" wire.

Pin3 - GND
Pin5 - Activation Input

Or did I miss something here? Perhaps you are able to control more then one channel via the GSM-Auto then It would make sense to hack the FOB for unlock and start maybe.




Posted By: scottdw
Date Posted: February 14, 2011 at 2:15 PM
KPierson wrote:

I'm not sure what the question here is - it sounds like you have it all figured out. There is a nice solder spot for one side of the button but the other side is a small via that will be harder to interface with.

One other thing I would suggest is to replace the battery in the transmitter with a power supply connected to constant power - this way the fob will never die!


Wow thanks for the fast replies. I must have given you the impression I knew what I was talking about...just a good guess I guess posted_image

Also yes I did eventually want to hook the other relay to the lock/unlock

So what points are you talking about and does it matter which one I use for "C" and "NO"?
I added a new pic with what I "think" might be right...can you take a look?
On the pic "3" would be connected to "C" and 5 would be "NO"...it this correct?
Also if I wanted to hook up the lock/unlock I guessed I would use the same point "8" (same as "3" above) which would connect to "C" and "7" which would connect to "NO" but I was not sure which "7" to use.
Here is the pic:
Highlighted Pic

Really appreciate your help on this. I have just enough knowledge to be dangerous posted_image




Posted By: Twelvoltz
Date Posted: February 14, 2011 at 2:21 PM
Again...there is no need to hack up the remote.

Your Avital unit has what it needs for that GSM piece activate the remote start by pulsing the H1/4 WHITE/ Blue activation input wire. This wire activates the remote start when it sees the same number of ground pulses as number of presses on the remote. In other words, if your unit requires 2 presses of the star button to start, the WHITE/ blue would need to see two ground pulses to start. So, if the system is not already programmed to do so, set your unit to only require one press to remote start.

What is the make/model/year of the car? Once you post this information someone here will be able to guide you through what is required to activate the locks.


-------------
Installer, IT support, and FFL. I need less hobbies.




Posted By: scottdw
Date Posted: February 14, 2011 at 2:32 PM
Twelvoltz wrote:

Again...there is no need to hack up the remote.

Your Avital unit has what it needs for that GSM piece activate the remote start by pulsing the H1/4 WHITE/ Blue activation input wire. This wire activates the remote start when it sees the same number of ground pulses as number of presses on the remote. In other words, if your unit requires 2 presses of the star button to start, the WHITE/ blue would need to see two ground pulses to start. So, if the system is not already programmed to do so, set your unit to only require one press to remote start.

What is the make/model/year of the car? Once you post this information someone here will be able to guide you through what is required to activate the locks.



Thanks...I was trying not to mess with the unit itself in case I messed something up. The GSM-Auto can also be set to send out 2 pulses if need be which is what I was going to do when hacking the keyfob. My truck is a 2001 Dodge Durango.
So if I decided to go this route which I am still scared to do, what terminal would I hook the WHITE/ blue wire to on the GSM...the "C" or "NO" and what would I hook the other to on the Avital?

Thanks for helping out.




Posted By: awdeclipse
Date Posted: February 14, 2011 at 3:04 PM
Hacking the FOB makes sense for a factory remote start. Like mentioned in the link you provided. Being that you are aftermarket, the functionality is there to hardwire and eliminate that step.

Activation input from the AVITAL would go to the NO terminal, the C terminal would go to ground. So when the "pulse" is sent, a pulsed ground would be "seen" by the avital on the activation input.

I read the manual briefly on the GSM-Auto, I don't believe it can control both relays independently can it?

Also, I personally would not interface to the lock/unlock on the FOB because its a flip/flop type button. Not like a factory FOB which has designated Lock and Unlock most times. If you send a signal and it doesn't register, your lock/unlock state is then unknown in that case.

Better solution would be to tie into the lock/unlock wires from the AVITAL directly. I personally would choose unlock functionality over lock since you will have to choose one. Better to have the need to remote unlock your car and be there to observe when it happens, as opposed to remote lock it, not knowing if it actually locked. Think of an OnStar commercial or something similar.




Posted By: scottdw
Date Posted: February 14, 2011 at 7:18 PM
awdeclipse wrote:

Hacking the FOB makes sense for a factory remote start. Like mentioned in the link you provided. Being that you are aftermarket, the functionality is there to hardwire and eliminate that step.

Activation input from the AVITAL would go to the NO terminal, the C terminal would go to ground. So when the "pulse" is sent, a pulsed ground would be "seen" by the avital on the activation input.


That makes sense. Sorry but I am a total NEWBIE but to hook the C terminal up to ground, where would be the best place to hook it to?
Can I just hook it to the negative line for powering the GSM or is that totally wrong.

awdeclipse wrote:


I read the manual briefly on the GSM-Auto, I don't believe it can control both relays independently can it?



They can be controlled separately but the second would have to be controlled by TXT message only.

awdeclipse wrote:


Also, I personally would not interface to the lock/unlock on the FOB because its a flip/flop type button. Not like a factory FOB which has designated Lock and Unlock most times. If you send a signal and it doesn't register, your lock/unlock state is then unknown in that case.

Better solution would be to tie into the lock/unlock wires from the AVITAL directly. I personally would choose unlock functionality over lock since you will have to choose one. Better to have the need to remote unlock your car and be there to observe when it happens, as opposed to remote lock it, not knowing if it actually locked. Think of an OnStar commercial or something similar.


I would only be using this every once in a while anyway and yeah I think the unlock would be the best bet.

I also re-read the manual and I cannot control how many pulses it sends so I would have to change the Avital to remote start on one pulse...I assume I can do this.

Thanks for helping me out I know my knowledge is very limited bur I appreciate you answering my stupid questions.

Scott




Posted By: Twelvoltz
Date Posted: February 14, 2011 at 8:57 PM
scottdw wrote:

That makes sense. Sorry but I am a total NEWBIE but to hook the C terminal up to ground, where would be the best place to hook it to? Can I just hook it to the negative line for powering the GSM or is that totally wrong.

Yes, the negative input is the same as ground. You could probably solder it to the ground wire that is already connected to the 4100.

To change the activation pulses, turn the ignition on then off, press the programming button 9 times, holding it in on the 9th press then press lock/unlock button on the remote. This should change it to one pulse starting.

-------------
Installer, IT support, and FFL. I need less hobbies.




Posted By: prdjr165
Date Posted: February 15, 2011 at 2:31 AM
where did you get the GSM switch from?What brand of sim card did you use and was it hard to proigram?




Posted By: scottdw
Date Posted: February 15, 2011 at 6:42 AM
Twelvoltz wrote:

scottdw wrote:

That makes sense. Sorry but I am a total NEWBIE but to hook the C terminal up to ground, where would be the best place to hook it to? Can I just hook it to the negative line for powering the GSM or is that totally wrong.

Yes, the negative input is the same as ground. You could probably solder it to the ground wire that is already connected to the 4100.

To change the activation pulses, turn the ignition on then off, press the programming button 9 times, holding it in on the 9th press then press lock/unlock button on the remote. This should change it to one pulse starting.


Awesome...thanks and will try it out.

I assume I can use the other channel for the unlock bu using the the Blue (-) unlock wire to the "NO" terminal and just use the same ground for "C", right?

[QUOTE]where did you get the GSM switch from?What brand of sim card did you use and was it hard to program?[/QUOTE]

The link for the GSM is in my first post but I have not tried to program it yet. I am probably going to try T-Mobile for the sim but you can use any network as long as it's GSM. I will post back once I get everything working though.




Posted By: awdeclipse
Date Posted: February 22, 2011 at 3:31 PM
scottdw wrote:


I assume I can use the other channel for the unlock bu using the the Blue (-) unlock wire to the "NO" terminal and just use the same ground for "C", right?




Yes. You may want to diode isolate the brain but I am not sure it would be necessary. Also it would not hurt to be sure you see (-) on that blue unlock wire while unlocking via remote.




Posted By: scottdw
Date Posted: March 29, 2011 at 12:36 PM
I meant to write back to this before. I got it all working and it works great. I used the remote starters power and ground and just piggy-backed off the ground to the relays ground. Found the activation input wire and hooked that up, programmed the unit via txt messages and it works fantastic.

I assume this won't be too much of a draw on the battery since it's on constantly, right?

I debated on wiring in a switch on the power wire so I can just cut power to it if we are away on vacation of something.
Would leaving this running for say a week (without the car being started) kill the battery by the time we get back?



Thanks for all of the help with this.




Posted By: awdeclipse
Date Posted: March 30, 2011 at 9:18 AM
Is there any specs on power consumption in the paperwork it came with? That will help give you an answer on what to expect regarding battery draw and how long it would last.

I think a switch on the power to the GSM box is good insurance regardless myself. Never know what kind of fluke might happen that would cause the car to start..

Does that box have any kind of timer that will shut the car down after xxx mins?




Posted By: scottdw
Date Posted: March 30, 2011 at 9:41 AM
Ok it says Operating Current: Max. 500mA, typical 55mA does that help.

Yes the car would shut down after 10min and can only be started from my cell phone. It has a whitelist that you can block all numbers except what is on the whitelist.

Thanks for the help.





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