My remote entry used to set off the alarm because it wasn't properly hooked up to the factory antitheft computer. I fixed that problem with the addition of 2 relays (do a search on this if you have the same problem), but this caused another problem.

Because the remote's unlock wire is connected to the power lock button inside the car (which is also connected to the driver door lock switch), it turns out that unlocking the doors with either the main button or the driver door switch would trip the relay and disarm the antitheft system. This means if someone busted in my window and unlocked the door, my relay would helpfully disable the alarm for them. Needless to say, this is not good.

To fix the problem, I put in a diode on the remote entry unlock wire between where the relay is attached and where this wire reaches the existing unlock wire. Problem solved. The only tricky part is that the unlock signal is a negative pulse so you have to put the diode in backwards (ie cathode end faces the remote entry unit, not the factory lock button).

I'm not sure if Sentras and such are wired the same as the G20 but I would bet money they are, so it's worth checking.

The doorlocks run off of a negative pulse, which is what most aftermarket alarms/keyless modules put out anyways. Is there a reason that they used relays (unless the doorlock output is +12V)? You are correct in using a diode between the unlock wire and the factory alarm disarm wire (green/yellow on most Nissans, at the doorlock module). If the Factory Disarm wire is not hooked up, then the factory alarm may go off at times because it thinks the car is getting broken into. Just a FYI for those with an aftermarket keyless. Good call jbloggs_c.

The door lock output is a negative pulse. I used the relays because the alarm's arm/disarm function uses a +12V pulse.

Originally posted by jbloggs_c
My remote entry used to set off the alarm because it wasn't properly hooked up to the factory antitheft computer. I fixed that problem with the addition of 2 relays (do a search on this if you have the same problem), but this caused another problem.

Because the remote's unlock wire is connected to the power lock button inside the car (which is also connected to the driver door lock switch), it turns out that unlocking the doors with either the main button or the driver door switch would trip the relay and disarm the antitheft system. This means if someone busted in my window and unlocked the door, my relay would helpfully disable the alarm for them. Needless to say, this is not good.
This is one of the reasons I used an alarm rather than just a simple keyless entry set-up. Using your scenario, the window breaking would trip my aftermarket alarm, and hitting the switch would not disable it. It would continue to go off even if the OEM was disabled. On mine, I also disconnected the door lock and the door switch from the OEM arm and disarm wires and wired only my aftermarket alarm to control the arming and disarming. Been extremely reliable in the 7 years it's been installed.

Originally posted by jbloggs_c
I'm not sure if Sentras and such are wired the same as the G20 but I would bet money they are, so it's worth checking. Yes they are, and so are the 1st & 2nd gen. Altimas and the 95-99 Maximas. If you've done one, you've done all of the above.

I wanted to stick with the stock antitheft because it has switches for all 4 doors, trunk, hood, is already integrated with the factory lock system and has a starter disable. It turned out to be a lot more work than I ever imagined to get the remote functioning properly but now that it is, I'm glad I went that way, save for the horn honking feature which is pretty much pathetic.

You can also go to http://www.bulldogsecurity.com/wires2/companylist.aspto and you can get wiring diagrams and info to help. Apparently Nissan uses a screwy one wire lock/unlock in B13's with factory power locks, which doesn't affect most B13 owners, since most B13 are E's, XE's or SE-R's in my experiences, none of which had power locks. Anyway, there it is nonetheless.

Originally posted by jbloggs_c
I wanted to stick with the stock antitheft because it has switches for all 4 doors, trunk, hood, is already integrated with the factory lock system and has a starter disable. It turned out to be a lot more work than I ever imagined to get the remote functioning properly but now that it is, I'm glad I went that way, save for the horn honking feature which is pretty much pathetic.
Think you've got me mistaken. I added an aftermarket alarm to control the factory one. I didn't scrap the OEM, as I kept it for the reasons you mentioned, but I just wanted to supplement it with protection the OEM didn't come with. I now have glass breakage and interior motion protection that the OEM didn't have, nor could it be added to the OEM. Not to mention a second set of door/trunk/hood triggers just in case the factory ones fail, and a second starter disable as well. If you manage to bypass the factory starter kill (not hard), you'll have to find my other one (not easy at all) to get the car started. Plus, the way I have it wired, if I put it in valet mode, it functions exactly like the OEM, with my new remote controlling lock/unlock. You can turn off the horn honk on the OEM alarm also. That was done the first day I had it. Hated it also.

Yeah I can add shock sensors and all that to the unit I have but at this point I'm so sick of cutting up wires I'm just going to let it be. Also I figure if I ever feel the need, my unit also has its own starter kill output. Did you disable the horn honk by just cutting the stock antitheft horn honk output? I'm planning on adding a new siren eventually to replace the horn honk. Probably put in a confirmation beep too.

Originally posted by jbloggs_c
Did you disable the horn honk by just cutting the stock antitheft horn honk output? I'm planning on adding a new siren eventually to replace the horn honk. Probably put in a confirmation beep too.
I looked in the manual, and iirc, I think if you hold the lock & unlock buttons on the OEM remote for 3 sec., the lights will flash and the horn honk will be disabled. Adding in a siren is another good thing in my opinion, as it's easier to detect the combo of horn and siren when an alarm is sounding. Helps identify yours from the masses of other alarms. I added two.

Two? Nice. I don't have an OEM remote because they didn't have it yet in 91. I'll have to find some other way of doing it.