Power Door Locks Circuit Diagram

[rob93]

Does anyone have a circuit handy for the power locks on a 1994 f250?

Or better yet, I am trying to add keyless entry via a micro controller in my truck (school project). I have programmed and set up a circuit which gives me a momentary 5 volt signal which is triggered by a key fob, now I just need to figure out how to control the unlock/lock with that signal. I understand that the lock is moved by a motor in the door panel.
I would like to keep my truck as un-molested as possible, i.e. splicing a signal into a wire in the factory harness, and of course still keep the lock button on the door panel.

Can anyone point me in the right direction?

 

[smolkin]

I put an aftermarket keyless entry system on the old '90 I just sold. It isn't hard to do. These trucks use a polarity-reversing lock/unlock system, not a trigger-wire set-up like some other cars I've seen. I don't have a diagram handy (maybe another member does?) but basically, there are two wires, pink/orange and pink/black, that carry the 12V + and ground to both lock motors. I recall that it's easiest to get to them from the pass side interior where the wires come through from the door, as this is also where the power for the circuit comes in. A little trial and error with a jumper to the battery will tell you which polarity is lock and unlock. You just have to tie in to those wires with a couple sets of relays (rated at 10A or better), set up to act like a DPDT switch.

 

[rob93]

Found some good links with the circuit diagram and an explanation of the way the locks work. Thanks smolkin.

http://www.bulldogsecurity.com/bdnew/vehiclewiringdiagrams.aspx

http://www.bulldogsecurity.com/manualsnew/KE1702 ManualLOW.pdf

So it looks like the f series are what the second link calls "Type C Reverse Polarity". Looking at the diagram on the top left of page 12, can I just put a relay in each of the "cut here" locations, for both the unlock and lock signal from my remote?
The only thing is it seems like this would remove the function of the switch on the door because the circuit would be open where the relay is, unless the relay gets the signal from my microprocessor to close the circuit....
I feel like I am over thinking this.

 

[smolkin]

I made a thing. Disclaimer: I am neither an EE nor an artist.

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Not sure about polarity, may be reversed.

 

[rob93]

Thank you for that. I found a very nice 4 relay shield for my micro controller that should work perfectly.
Like this one http://www.ebay.com/itm/12V-4-Chann...M32-A117-/261108909170?_trksid=p2054897.l4275