Creating a delayed 2nd lock output?

Hi everyone...

I'm trying to create a 2nd unlock output (for driver's priority unlock) for an alarm that only offers 1 unlock output for my 2001 GMC Yukon.  There is one wire that will trigger the driver's door unlock relay upon receiving a (+) signal and a 2nd wire that will unlock the remaining doors upon receiving a (+) signal.  I can set the alarm to provide 3.5 second output (even though I only need a 0.8 second pulse to unlock the doors).  Is there some combination of relays, diodes, and capacitors that would allow me to create a second (+) unlock pulse when a 2nd unlock signal is sent within that 3.5 second output from the 1st unlock signal? 

I have a circuit using 2 relays + 1 diode that I think will NOT work because there is no delay in powering the 2nd relay.  I can't draw diagrams, but here goes:

Relay 1: 
30 - (+)12 V
86 - Ground
85 - (+) door unlock output (3.5 second) from alarm
87 - output to (+) vehicle driver door unlock wire AND to 30 of Relay #2 with diode between the 2 relays. Band faces Relay #2

Relay 2:
30 - +12 V in from relay #1 (see above)
86 - Ground
85 - (+) door unlock output (3.5 second) from alarm (same as relay #1 above)
87 - output to (+) vehicle all door unlock wire.

I don't think the above circuit will work because it seems that both relays would just energize simultaneously and provide + impulses to both driver's and all door unlock wires at the same time.  Is there some way to induce a 1/2 to 3/4 second delay before providing +12V to the 2nd relay?  If I could do this then here's what I envision:
Press unlock button once --> Relay 1 energizes for 3.5 seconds, send + pulse to driver's door unlock wire and eventually allows relay 2 to have +12 volts
Press unlock button again (within 3.5 seconds) - 2nd relay sends +12V pulse to all doors unlock wire.

Is this possible?  Would this be easier to achieve with some sort of aftermarket product like a DEI pulse generator or timed relay?  If so, anyone know of a good online source for said DEI parts?

Thanks so much!

Hi Alvin, you can unlock all doors, including the driver's door, with the White wire at the door lock relays located just above the gas pedal in a 2001 GMC Yukon.

the12volt

With some factory fitted units, the first press unlocks the drivers door and the 2nd unlocks the remaining doors. Is this what you're after ?

The previous reply is only suitable if you want all the doors unlocked at the same time everytime.

Sorry, one more thing.

I believe you will need an alarm output that is only on whilst the button is pressed. If the 3.5s output is initiated and the button is pressed again at 1.5s, how will this change the original 3.5s ouput ?  I think you need to be able to differentiate between each press during the 3.5s on time.

If you had a shorter output pulse from the alarm or didn't care about having to wait 3.5s (the drivers door pulse would have to end) before unlocking the other doors, you could use 2 relays set-up as a flip flop to driver each unlocking circuit with each alternate press of the unlock button. 

Hi Scott, if his alarm has a dedicated disarm button that supplies an output each time it is pressed (unlike most that arm, disarm, and panic with the same button), he could use relays along with a few other parts to control it as you described, but chances are it doesn't.... so if he wants to add the driver's priority unlock feature and given that he only has one output for unlock (during disarm),  rather than trying to do it all from the single unlock output from the alarm, here are two ways to add the feature.

First, I'd use the alarm's unlock output just to unlock the driver's door and use an auxilary output from the alarm to unlock all doors, granted the alarm has an auxilary (2nd channel) output. 

Second, if the alarm does not have an auxilary output and we know it only has one unlock output, I'd add a channel expander that would provide him with an addtional output to unlock all doors that would be activated by arming and diarming the alarm within a few seconds. The channel expander could still be added even if he has auxilary outputs and wanted to add another.

And it's possible that other options may exist because we still do not know what alarm he's installing.  ....Alvin?

the12volt

Hi Scott and the12volt...

Thanks so much for the replies! 

First of all, the alarm is an Autopage RS-750 LCD.  It does have a 2nd wire that can be used for the driver priority unlock function, but that same wire is also used for the factory security system bypass.  You have to program the wire for one or the other and can't have both at the same time.  Since my Yukon has the factory alarm I'll need to use the wire for the factory security bypass.  The remotes have dedicated lock and unlock buttons (one of the reasons that I chose the Autopage), so sending 2 unlock presses in rapid succession is not a problem.  Yes, the alarm does have a 2nd auxilliary (-) output that could be used to unlock the other doors, but that would mean pressing the unlock button and then the auxillary button to unlock all doors.  Moreover, pressing the aux button without first unlocking the doors might trigger the alarm since the dome light go on when the doors are unlocked.  If all else fails, I will use the auxillary output (or perhaps just go back to unlocking all doors), but I was hoping that it might be possible to maintain the driver's priority unlock much like the factory setup. 

Scott - I did some more thinking about that 2 relay circuit that I proposed and realized that it would do nothing special other than unlock all the doors at once.  Yes, I can set the unlock output to 0.8 seconds and I'm interested in hearing more about the "flip flop" idea you mentioned. 

Another idea I had was to set the unlock output for 0.8 seconds.  The 1st press of the remote would send a (+) unlock output that would unlock the driver's door as well as triggering a time-countdown relay (say 3 seconds or so).  The time-delay relay would energize a 2nd relay so that a 2nd press of the unlock button within those 3 seconds would allow a (+) pulse to be sent to the white wire that unlocks all doors.  I looked through the relay diagrams on this web site, but didn't seem to find anything that exactly fit this description.

I apologize if this is too confusing, but I really do appreciate all the help & knowledge that you guys have!

- AlvinWang

Hey Alvin,

Go see your post in the Security section......answers are there!  

Hi Alvin

Your last idea sounds the best but for one thing. You will need the timed relay to switch on when the first press is released. This will then direct the next press to the white wire.  The timed relay can have the drivers door on the NC output and the the other doors on the NO ouput.

i.e. First press, signal goes out NC, drivers door unlocks, button released , relay switches for 3secs, next press inside the 3secs, signal now goes out NO(white wire), 3secs pass and relay relaxes, drivers door is now the primary output again.