Aftermarket remote door locks don't work

[slownis]

I bought my '92 Ranger last year. The previous owner had an aftermarket remote starter and door lock kit installed professionally. The remote start function works, but when I push unlock or lock on the key fob, the turn signal lights flash but nothing else happens. I narrowed it down to a relay looking thing that was installed inside the driver door, that has wires going to the lock switch in the door, as well as the 'brain' unit it up under the dash. Can anyone tell me if one of these would work as a replacement?

http://www.commandoalarms.com/itm40077.htm

 

[RobbieD]

Yeah, it could work with the reverse-polarity doorlocks that your truck has. Unless your alarm system is one of the models listed in the ad, you may need to modify the harness that plugs into the alarm brain. Make sure your alarm gives negative pulse outputs for the doorlocks. And you'll most likely need to splice in the new module's output harness to the truck's doorlock wiring.