treimche

I am a remote starter and alarm installer and about to tackle my S2000, but the door lock wiring is annoying. I see there is 2 different ways to do it, with the more common being reverse polarity. Not a big deal at all, done it many times, but I am not a fan of cutting wires if I don't have to. I'm going to be trying to figure out if there is a way to just do negative pulses like most normal cars. Just wondering if anyone has figured anything out like this before? I will probably pull the OEM keyless entry unit apart and see if there might be a way to connect negative locks inside too. Regardless of what I find I can post info/pics when finished.

modifry

There are 2 pins on the OEM keyless entry module that will lock/unlock with a negative pulse. The OEM security module triggers them, but even if the OEM security is not present on the vehicle those pins still work but will not have wires attached. I don't remember which 2 pins off the top of my head but you can look it up.

NOTE - Alarm systems usually use bipolar transistors in an "open collector" arrangement for the door lock pulses. This means the ground pulse isn't actually at ground, it's a few tenths of a volt above ground. Some manufacturers use the very common darlington driver chip ULN2003 for the low-current triggers (500ma), which is even worse because you have a double voltage drop through two transistors. Most cars don't care, but the S2K does. If you trigger the keyless module directly at those two pins you may find that it works fine in warm weather, but when it gets cold the the transistor CE voltage drop increases and the locks may be intermittent or stop working altogether. The cure is to use the alarm trigger outputs to activate a relay (mechanical or FET-based) to trigger the keyless module. If you are totally anal like me you can open up the alarm and install N-FETs inside to bypass the ULN2003 driver to avoid the problem.

treimche

Haven't had time to post my results yet but here it is, hopefully this can help someone out in the future. I opened up the factory keyless unit and started testing. It turns out that its totally possible to avoid using relays to "5 wire" the door lock wires. There are 3 contact points inside the keyless unit that I soldered wires onto. 1 locks both doors, 1 unlocks the drivers door, and 1 unlocks the passengers door. Here are the pics I took:




I was inspired by this thread: https://www.s2ki.com/forums/s2000-el...-guide-998314/ but it looks like he said that was based on a JDM RHD S2000. Mine is a plain old 2005 AP2 so it was way different, but got it figured out anyway.

modifry

The lock/unlock triggers are available at pins 11 and 12 on the connector so no need to open the box if that's all you need. If dealer security was installed, pin 11 will have a grn/red wire and 12 will be blk/wht but without security there are no wires on those pins. You'll have to install new terminals or solder to the pins. You can locate 11 and 12 by looking for a yel wire on one corner of the connector, that's pin 9. Next to it is a yel/blk, pin 10, then of course 11 and 12.