Adding Auto Lock and Unlock to Factory Alarm, 2008 Honda Civic

I have a Honda Civic mk8 2008 with the standard push start, factory fitted alarm and central locking system.Apparently, some models have this feature and some dont, and mine doesn't.Can I add a door lock and unlock feature so when I start the engine, the doors lock and when I stop the engine, the doors unlock ? I did look at the articles on here and there was one showing how to do this on cars without an alarm but not with an alarm already fitted.

Diagrams 15 and 16 on this page You can do this with an existing alarm. It says without, because if you had an aftermarket alarm you would be able to program this feature into the alarm.

Power Lock      green or blue      -      driver kick, door harness, white 18 pin plug, pin 16      Directwire       Power Unlock      gray      -      driver kick, door harness, white 18 pin plug, pin 12      

Ah, OK. I'm surprised I need 4 relays to do it though.What size relays would I need and am I right in saying that two of the relays show a built in diode?

You can use a 452T that cost about $10 on Amazon. https://www.directeddealers.com/manuals/ig/accessories/245231_452T_(9_wires)_Installation_Guide.pdfSteve G

Hook up the following wires from the 452T. Red to constant +12 volts. (White) Black to chassis ground. Violet to ignition wire. (Blue) Blue and Green to the lock/unlock wires listed in previous post by “I am an idiot”Steve G

See them available for $7-$8 on eBay also.Steve G

Thanks for the help folks.That 452T is just the thing I need.I am in the UK and I cant find anyone selling them over here but I will ask some of my local Clifford alarm installers if they can get one for me. Cheers.