Need to slow dome activation
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=76704
Printed Date: May 23, 2024 at 3:31 AM
Topic: Need to slow dome activation
Posted By: tikech
Subject: Need to slow dome activation
Date Posted: April 24, 2006 at 5:06 AM
I have installed keyless entry in to my car with a factory alarm. All functions work well except that when I unlock the car the dome light wire is grounded a fraction of a second before the doors unlock and the factory alarm disarms. This causes the horn to "chirp" for a short time as the factory alarm sees the ground from the keyless entry on the door pin wire as the door opening, thus setting off the alarm. As soon as the doors unlock the alarm stops.
Is there some way that I can slow the dome light activation for just a split second? Would adding a resistor to the dome light wire from the keyless entry achieve this?
Thanks for your help.
Replies:
Posted By: KPierson
Date Posted: April 24, 2006 at 6:24 AM
Any chance of diode isolating your dome light output to your factory disarm? This way, the dome light output would disable the OEM alarm, of course this is depending on the car you have, which you didn't list. You could get an on delay timer and set it really low, to .5 seconds or something like that. Depending on how much of a delay you need you could possibly use some digital buffer gates to slow the signal down, but I'm thinking you would need quite a bit of them, and the relay would be much easier. ------------- Kevin Pierson
Posted By: dualsport
Date Posted: April 24, 2006 at 10:11 AM
You could try adding a diode, resistor and cap before the input to your alarm, like this-
This is assuming it's a negative trigger, and the alarm trigger input is high impedance. If it isn't because there are other things hooked up to it, then you can add the buffer to drive it, without affecting the timing.
You'll probably want to play around with the values of the cap and resistor to get the amount of delay you want; smaller resistor and cap values will reduce the delay. If you only need a split second delay, you can use a smaller cap, for example.
Posted By: tragik
Date Posted: April 24, 2006 at 12:35 PM
These timer circuits should work fine, but usually take more time and effort than just tagging each door trigger and diode isolating them from each other. What kind of car do you have? Also, i wouldn't recommend disarming the factory alarm with the dome light. Doing that causes you to lose the added protection of a factory system. I know that doesn't offer anything that your aftermarket unit does, but any extra protection helps. ------------- Northstart.....or start it your damn self.
Posted By: KPierson
Date Posted: April 24, 2006 at 12:41 PM
Connecting the dome light output will NOT bypass the OEM alarm, as long as you diode isolate it! Only the alarm turning on its dome light supervision circuit will disarm the OEM alarm, not simply opening the door. Its not the best way to wire an alarm up, but it is possible that it may fix his problem quickly and easily.
-------------
Kevin Pierson
Posted By: dualsport
Date Posted: April 24, 2006 at 1:20 PM
Sounds like more specifics on the current setup is needed; since it's the factory alarm he's dealing with, with an aftermarket keyless entry unit.
I originally thought the trigger for the alarm may be readily accessible, but if it isn't, or tied in to other things, it complicates things.
What's causing the dome light to come on when using the keyless entry? If you set up the keyless entry to duplicate what happens when you open it normally with a key, there shouldn't be a problem.
Posted By: tikech
Date Posted: April 24, 2006 at 2:00 PM
Thanks for all the suggestions, here is more info on the setup. The car is a 95' Mercedes E320, with a crimestopper CS-865.RKE.II. The system was working fine until I made a change the other day. The car has two different dome lamp circuits, I.e. if you open the front door only the front dome lights, if you open a back door only the back dome lights. I had the dome lamp supervision from the crimestopper hooked directly to the front dome lamp circuit/door pin and all was fine. I then decided that I want the crimestopper to control the front and back dome lamps. Since the crimestopper has a built in 10amp dome lamp relay I tried to just diode isolate the two circuits, the lamps were very dim. The now I have the crimestopper driving two relays that are tied in to the dome lamp circuits, and am getting the brief sounding of the alarm horn as the car is unlocking. I don't understand why it was fine before I added the relays, the alarm never sounded before the change. I hope this gives you guys some more info to work with. Thanks for all your help.
Posted By: dualsport
Date Posted: April 24, 2006 at 6:44 PM
Just out of curiousity, what would happen if you tried temporarily disconnecting the control to just the rear dome light relay you added? Maybe the factory alarm has different trigger timing for the rear door switches. You might be able to just add a short delay to the dome lamp supervision signal from the Crimestopper, if it needs a bit more time for the locks to cycle open and disarm the factory alarm.
Posted By: tikech
Date Posted: April 24, 2006 at 10:20 PM
dualsport, I tried disconnecting the relay controlling the rear lamp, same result. Just for kicks I disconnected the relay controlling the front lamp, problem went away. I hooked the system back up as before, crimestopper dome wire directly to the front dome lamp circuit and it worked great. For some reason when the crimestopper is used to switch a relay connected to the dome lamp circuit I get the brief honk of the alarm horn. Burr!
Posted By: dualsport
Date Posted: April 24, 2006 at 11:57 PM
Did you try having the rear dome light relay hooked up with the front one disconnected too?
Would you know if your factory alarm is triggering on the door switches going to ground, or possibly some kind of current sensing? Maybe without the relay, the current pulled from the dome lights is just below the trigger threshold.
Just grasping for straws here- 
Is that 10A output from the crimestopper dome supervision a ground switched signal?
Posted By: tikech
Date Posted: April 25, 2006 at 1:17 AM
Yeah I did disconnect the front relay with the rear still connected, all worked great then. The factory alarm triggers from the door pins going to ground. The 10A output from the crimestopper is set as a ground signal, even though it can be via a jumper switch to be a 12+ signal. I think I may follow KPierson suggestion and connect the crimestoppers dome lamp output to the factory alarm disarm wire with a diode so that it will disarm the alarm as soon as the lights switch on. I just don't understand how adding those relays for the dome circuits are causing this problem. If anything I would think that adding a relay in between the crimestopper and the dome circuit would slow things down. This is just bugging me.
Posted By: KPierson
Date Posted: April 25, 2006 at 6:06 AM
I like dualsports sugguestion that it may be current related. You're relays are going to pull a significant amount of current over a dome light. Thats the only thing that makes sense to me. It also seems like you should be able to diode isolate the two circuits and make them work, I would double check that you had the diodes facing the correct way, and that both diodes were big enough to handle the current, and both working properly. Beyond that, I am still thinking hooking the dome light supervision output of the alarm will eliminate the factory alarm from going off when you disarm. Good luck! ------------- Kevin Pierson
Posted By: dualsport
Date Posted: April 25, 2006 at 10:53 AM
Yeah, if you have a separate alarm disable input on your factory alarm, that would be the best way to go; just connect the dome light control from your keyless entry to it with the diode. How is it currently hooked up? Does the factory alarm also disarm just from the door locks unlocking?
It shouldn't compromise security if you do it as Kevin suggests, since it's only going to be active when the keyless entry is activated.
I would guess the diodes originally tried for direct control of the dome lights from the 10A control were too small to handle the current. I usually don't like to use diodes to drive powered stuff unless it's really necessary, best using them primarily for signal control.
Posted By: KPierson
Date Posted: April 25, 2006 at 12:52 PM
Something else that is strage is the fact that the alarm module isn't disarming the OEM alarm before turning on the domelight output. Typical chain of commands would be: Disarm OEM alarm, then Unlock Doors, then turn on dome light. Keep us updated on the progress, I would love to know what fixes it in the end. ------------- Kevin Pierson
Posted By: tikech
Date Posted: April 28, 2006 at 8:59 PM
KPierson wrote:
Something else that is strage is the fact that the alarm module isn't disarming the OEM alarm before turning on the domelight output. Typical chain of commands would be: Disarm OEM alarm, then Unlock Doors, then turn on dome light. Keep us updated on the progress, I would love to know what fixes it in the end.
When I had the crimestopper dome light wire hook directly to the front dome lamp\door pin circuit it worked just as it should: Disarm OEM alarm, then Unlock Doors, then turn on dome light. It's like the adding the relays somehow sped up the dome lamp activation. This may not make any sense to you guys in the know, but I think that the relays that I added were just putting a much stronger\cleaner ground signal on the dome lamp circuits then when the crimestopper was directly grounding those same circuits. It also had nothing to do with the newly added rear dome lamp circuit, I tapped into that circuit at the rear dome lamp switch on the center console. After studying the wiring diagram noticed the OEM alarm and door switches were wired before the console switch with I diode isolating them. The dome lamps are after the console switch. So when grounding the circuit from the console switch only the lamps were getting ground and the signal was stopped at the factory diode isolating it from the OEM alarm so that you could turn on the rear lights with the alarm set. They didn't use this setup in the front because the front dome lamp and switch are in the same unit with the front door pins only activating the timer in that unit. So enough rambling, how did I fix the problem. As suggested above I connected the crimestopper dome lamp wire to the OEM disarm wire. I did use a diode but not were you guys thought that I would need it. I had to add a diode, but it's to prevent activating the newly added relays from being grounded when unlocking the door with the key, as the micro switch in the door lock was grounding the circuit and activating the dome lamps while the key was in the unlock position. I didn't have to add a diode were subjected because the crimestopper dome lamp wire and the factory dome lamp circuits are not connected to each other. The crimestopper is just connected the the new relays that are connected to the dome lamp circuit so its is not possible to open the doors and disarm the OEM alarm. Sorry for the long post and thanks for all the suggestions.
Posted By: KPierson
Date Posted: April 28, 2006 at 9:12 PM
Congrats! Wow, I think we actually finally helped someone, we can shut the site down now!!! :) Thats an interesting problem/solution. Honestly, it doesn't make much sense to me, but its good to know its fixed and now operating how you want it to. Good job! ------------- Kevin Pierson
Posted By: dualsport
Date Posted: April 28, 2006 at 10:49 PM
My head's still spinning trying to picture the setup All that matters is that it works though-
What was the factory alarm disarm input hooked up to before you connected it to the dome output signal? Just wondering what was used to disarm the alarm before, if it wasn't connected-
Posted By: tikech
Date Posted: April 29, 2006 at 12:42 AM
dualsport, see the link below for a crude diagram of what we are talking about. The items highlighted in pink were added for this project\non factory. It would have worked great if I could have just added a diode like the one from the factory on the rear dome lamp circuit. The diagram doesn't show this but there are two other lamps on each circuit that are installed in the doors. To add a diode that did the same job as the factory diode would have required a lot of rewiring, A.K.A work! Before I added the dome lamp relays and connected the dome lamp wire to the OEM disarm wire, the OEM alarm was disarmed\armed whenever the car unlocked\unlocked. This was accomplished by the crimestopper locking and unlocking the central locking system on the trunk lock circuit. It is still armed in the same way, via the trunk lock circuit. https://www.vanpeters.com/benz/12volt.jpg I definitely have respect for you guys that do this for a living. I think its fun coming up with things to do on my own car. I have a good understanding of how this car is designed\wired. I could not imagine having to go from one car to the other, all designed by different companies and such drastically different in there setup. Thanks
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