convert momentary loss of ground to 12v?

As strange as it seems, my alarm (which is a compustar 2wss-as) grounds both of the lock/unlock leads at rest and shows neither ground nor positive current during the lock/unlock pulse.  ...this goes for both leads on the alarm harness.

I have three wire positive locks, so I need to turn this lack of a ground into a 12v pulse.  I can readily think of how to do this with relays, but it would involve keeping the relay coil charged at all times other than pulse, and we can't have that now can we. 

Any ideas?

Also, any ideas as to why this alarm does not have a (-/+) pulse?  It seemed to be a very nice unit, despite the fact that it cost me 300 dollars.  I must have got a lemon, too bad I bought it online - now I am stuck with this situation which could possibly cost as much in other equipment to fix as the alarm did.  :(

Mike  

Do not take this the wrong way but double check your testing procedure for the negative pulse. Red lead from DMM to a constant +12V and black wire from DMM on the door lock output wire. I looked up your system and it should provide a ground pulse for door locks and will require relays. You should be able to see the DMM go +12V real quick on arm/disarm depending on the wire your checking. I am guilty of and see many times a guy checking for a ground trigger with the negative lead from the meter on ground and the positive lead on the output wire out of habit.  Double check it and see what you get. Maybe a defective unit if all looks well?

I can deal with it not providing +12v as that is simple to convert, however, the strange thing is that I have continuity to ground at rest on both lock/unlock leads from the brain.  When an alarm, or anything thereof, says -200mah, this indicates the alarm drawing the noted amount of current whereby (-) does not guarantee it is a grounded connection?  That might seem a little confusing, but read it again and you should pick up on what I am asking. 

Also, if I connect the red lead on my meter to +12v constant, and the black to my lock/unlock lead, while monitoring amperage, should I see a decrease in amperage during the pulse of minimal proportion or a decrease in maximum proportion?  If measuring amperage is as is voltage, I should observe total loss of signal because during the pulse, continuity to ground is loss.  Correct or incorrect?

Thanks for working with me so far everyone, I do realize newcomers can be quite aggravating with all of their over-confirming questions! :)

Mike 

You should not be using the amperage setting at all to test for output polarity. Maybe that is the problem. You should be using your meter to monitor voltage with the leads as I described. Red lead to +12V and black lead to lock outputs from alarm.  Watch for +12V pulse as your locking/unlocking. With the meter set on voltage and the leads as described, you will see the +12V as long as your outputs are good. What concerns me is if you have been using the meter in amperage mode (red lead plugged into amperage port) that causes the red and black lead to essentially become the same wire. If you put one lead to +12V and the other to your door lock output (ground pulse) it is just like hooking the door lock output wire to +12V which is not good if its giving grounded output (short circuit and possibly blown outputs). Hope thats not the case =/

Good thing!  I have not tried the amperage test yet, I had too much to do today...but I would have probably done that!  doh I have done the voltage test you described and I am getting +12v when the outputs are not activated and nothing when they are.  No continuity to ground and no positive voltage present.  Hmm, maybe I have a lemon or maybe I have blown the outputs accidentally?  I tried to connect everything to convert it to +12v with relays and there is not sufficient current to activate the coils which are standard bosch 5-pole SPDT units, last time I checked all that was needed was 200mah to energize the coil.

Mike

are you hearing the relays click on arm/disarm?

Mgray] wrote:

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p>Good thing!  I have not tried the amperage test yet, I had too much to do today...but I would have probably done that!  doh I have done the voltage test you described and I am getting +12v when the outputs are not activated and nothing when they are.  No continuity to ground and no positive voltage present.  Hmm, maybe I have a lemon or maybe I have blown the outputs accidentally?  I tried to connect everything to convert it to +12v with relays and there is not sufficient current to activate the coils which are standard bosch 5-pole SPDT units, last time I checked all that was needed was 200mah to energize the coil.

Mike

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well 12v at rest sounds like they activate with a neg trigger.  take an inline fuse holder with a 1 amp fuse and touch the lock wire to a ground and see what the locks do.  if they werent supposed to go to ground the fuse will blow.   and describe nothing when activated, 12 volts at rest will go to 0.00 (or close to it) on neg triggers.  chryslers will go to one voltage on lock and a different voltage on unlock, becuase of the one wire and resistor set up.  also, i didnt see the vehicle mentioned in the thread.  what are you working on?  if the vehicle is like a toyota highlander, there is a specific setup to do locks.

Nope!  The relays I wire in are not clicking at all.  I did simulate the coil energizing and verified that they do work.  My car lock/unlock wires are grounded at rest.  It is a three-wire positive setup, '88 Camaro IROC-Z.

Maybe my expensive multimeter is toast as well, would one of the cheap 19.95 analog units suffice just for this little ordeal?

Yes, the meter appears well.  I took it apart today to check everything out, just in case something was loose in there meter.  All looked well, I even replaced the fuses just in case...

I have pretty much narrowed it down to the brain.  I took the case off and it looked brand new as it should, I am assuming I just got a bad unit or I shorted something internal, not visible to me.  That fact that it is grounded at rest and nothing at pulse (exactly opposite as it should be) leads me to believe some nitwit did something backwards, including any machines that made it! :)  ...or me, the nitwit, did something to fry it. 

The worst part is, of course, that I have no warranty because I did not take it to an authorized installer.  The seller is just as much of a pain in the ass as Firstech (compustar), so looks like I am out 280 bucks! :(

Too bad too, it was a nice unit with all kinds of neat little bells and whistles.

Mike

PS - I wish there was some way I could rig it off the sequencing of the parking light output, one flash is lock and two is unlock.  Hmm, any special equipment out there to do this that doesn't cost thousands to digitize the signal and all that BS? 

https://www.the12volt.com/doorlocks/page3.asp#3wp

Use that diagram to verify you have wired it like that. Once you know its wired correctly and if it still doesnt work try this. Disconnect the alarm outputs from the relays. Take a piece of wire and hold one end on a good ground then touch the other end to one of the relays on the pin that you pulled off the alarm output wire. It should cause your locks to unlock or lock. Then touch the wire to the other relay on the pin where your alarm connected to it. The locks should now do opposite of what they did on first relay. Grounding the side of the coil that connects to the alarm will simulate a grounded output from the alarm. If this test makes your locks work but they dont work when connected to the alarm then your alarm outputs are bad.