Need to slow dome activation

Home / the12volt's Install Bay / Car Security and Convenience / Need to slow dome activation (

Topic Closed)

Welcome Guest :)

Members

Next Page > < Prev Topic Next Topic >

tikech

Member - Posts: 20

Joined: April 04, 2002

Location: Georgia, United States

Posted: April 24, 2006 at 5:06 AM / IP Logged

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.

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 24, 2006 at 6:24 AM / IP Logged

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

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: April 24, 2006 at 10:11 AM / IP Logged

You could try adding a diode, resistor and cap before the input to your alarm, like this-

Need to slow dome activation -- posted image.

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.

tragik

Copper - Posts: 169

Joined: September 28, 2005

Location: Alaska, United States

Posted: April 24, 2006 at 12:35 PM / IP Logged

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.

KPierson

Platinum - Posts: 3,527

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 24, 2006 at 12:41 PM / IP Logged

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

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: April 24, 2006 at 1:20 PM / IP Logged

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.

tikech

Member - Posts: 20

Joined: April 04, 2002

Location: Georgia, United States

Posted: April 24, 2006 at 2:00 PM / IP Logged

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.

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: April 24, 2006 at 6:44 PM / IP Logged

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.

tikech

Member - Posts: 20

Joined: April 04, 2002

Location: Georgia, United States

Posted: April 24, 2006 at 10:20 PM / IP Logged

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!

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: April 24, 2006 at 11:57 PM / IP Logged

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- Need to slow dome activation -- posted image.

Is that 10A output from the crimestopper dome supervision a ground switched signal?

Next Page >

Printable version

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

Search the12volt.com

Follow the12volt.com

Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.