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Ford Open Circuit Door Pins

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Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
Printed Date: October 19, 2021 at 3:32 AM

Topic: Ford Open Circuit Door Pins

Posted By: soundnsecurity
Subject: Ford Open Circuit Door Pins
Date Posted: February 24, 2014 at 7:38 AM

i doing some research for an alarm im going to install on a 2010 F150 extended cab and i remember hearing something about the doorpins not being positive or negative, instead the circuit just goes open when you open a door. i look up a tech sheet and sure enough it says the pins are open circuit. what is the best way to interface with these doorpins? i would use the dome light but the alarm im installing doesnt seem to have the ability to remove the error chirp. any help would be appreciated thanks


Posted By: freqsounds
Date Posted: February 24, 2014 at 7:50 AM
I'm kind of in the same boat with my Saab.

Have you tried metering the wires to see if you get any (+) voltage or ground?

It may be possible that there is a voltage of some sort on the wire. Mine shows 4.1V when open, and 7.4V when closed, and the BCM turns off the circuit after 10 minutes, tricking the alarm into thinking all the doors are open.

Curious to see how this turns out.

No question is stupid or not worth asking. You were once a noob, right? :)

Posted By: harryharris
Date Posted: February 24, 2014 at 8:03 AM
If you're using DEI, either use a DB-ALL for these functions or in the programming set the door/hood triggers to N/closed from the default N/open.
Menu 1 items 13 and 14 option 1.

Test before boxing up.

Posted By: freqsounds
Date Posted: February 24, 2014 at 8:22 AM
The DBALL doesn't support the door triggers for Fords. They'd have to be hooked up through the alarm system.

@soundnsecurity, which alarm are you considering for your install? Also, which bypass module would you be using?

Still curious on the door trigger wires too! posted_image

No question is stupid or not worth asking. You were once a noob, right? :)

Posted By: harryharris
Date Posted: February 24, 2014 at 8:43 AM
So use a DEI system and program it the way I showed before.

Test before boxing up.

Posted By: kreg357
Date Posted: February 24, 2014 at 9:16 AM
While you could program the DEI system for N.C. door trigger, you can only connect to and monitor one door. Standard diode isolation
does not work.   There are a few ways to handle them. DEI makes the DTIMazda module for this style trigger or you could build the
module yourself, following the TechTip #1921. Here is a link :

Here is a pictorial on another Ford with these door trigger wires and his solution :

Soldering is fun!

Posted By: flobee4
Date Posted: February 24, 2014 at 6:22 PM
EVO-All by Fortin detects the door triggers according to their site. The DTIMazda is discontinued and is hard to find. If you don't want to do the Tech Tip with the diodes and resistors, use the EVO

Posted By: soundnsecurity
Date Posted: February 24, 2014 at 8:01 PM
ill use the diodes and resistors, its seems easy enough. im trying to avoid having to buy a whole bypass module just for the doorpin interface. thanks for the information i knew it was out there but my searches weren't getting anywhere.

Posted By: yellow_cake
Date Posted: February 27, 2014 at 5:10 PM
That tech tip is the way to go about it, used it on an 05 Mustang for door monitoring and works like a charm.

Posted By: sam369
Date Posted: February 02, 2015 at 1:30 AM
I wonder why DTIMAZDA was discontinued. Not many people need it?

Posted By: oldspark
Date Posted: February 02, 2015 at 6:03 AM
I'm curious about - and probably hijacking - SNS's OP "... doorpins not being positive or negative...".
That to me implies floating switches as often used for non-vehicle alarms - typically series chained NC triggers (window foil; reed or other switches; IR outputs, etc) which usually have dispersed resistors for impedance sensing circuits. (Forget the Hollywood cut or short of sensor & alarm wires - that's as valid as cutting bomb blue or red wires, or blowing keypads to open doors!).

For such systems, unless switch voltages are known, short or open detection circuits are required. The closest I can think of in common(?) automotive applications are blown-fuse detection circuits tho often they require or assume near +12V voltages at the fuse. (Blown bulb detectors are usually current sensing else assume grounded bulbs.)

The DEI techtip however refers to NC switches which AFAICSee are grounded.
Of course the techtip may work for floating switches that have a low enough impedance or reference to GND.

So I'm curious - are there "floating" switches - ie, 2-terminal door etc switches where neither is (direct) connected to GND; nor +12V for that matter?
Or is it a case of jargon where some refer to the floating output when the switch is open and that is confused with a floating switch?
[ The term floating itself means neither +ve or -ve. IE there is no reference to any rail/voltage except as thru pull up/down resistors else attached circuits like alarms which are usually relatively high impedance. ]

My curiosity is also partly a worry - did I recently reply crap in a recent thread? (No, not that thread.)
However that was about NC versus NO door etc switches - not floating - unless I misread or the OP was also confused as to what system was involved. (Maybe I'll revisit and check or ask if the problem was solved.)   

If there are no "floating" switches and it's merely a case of NC versus NO, then IMO there is no issue and I have indeed hijacked... tho maybe also forewarned some of other implementations or possible automotive system yet to come.   

Thanks in anticipation.

Posted By: another-kelly
Date Posted: February 05, 2015 at 1:13 PM
newer fords are N/C switches. ground when the door is closed and then go to either + some kind of voltage or an open circuit. a majority of the fords i've done, they go to +12V when a door is opened which allows me to use a positive door trigger input on the alarm and then diode isolate as required. however i recently worked on a newer mazda 6 and they only went to +4-5 volt when a door was opened. just did the pain in the butt tech doc with resistors/diodes for it

Posted By: oldspark
Date Posted: February 05, 2015 at 4:09 PM
Thanks. However that sounds like they are still NOT floating - ie, they still have one end connected to GND else +12V.

Most (traditional) car door etc switches are GND connected. IE - one end is GND.
For NO they - ie, the other end of the switch - only grounds when the door (etc) is open.   Otherwise that end is "floating" noting that in practice that means it's at +12V since it's usually connected via a dome light (low resistance) or high impedance sensing circuit which must be +V to detect when it is grounded.
A dome switch can mean a +12V impedance (resistance to +12V) if 1 Ohm or lower whereas a FET sensing circuit cam mean several mega-Ohms.
And it may be +3.3V or +5V or +8V etc if it is some sort of sensing circuit attached without a +12V doom light etc...
If diode isolation is used on all outgoing switch feeds then it will essentially be floating - ie, you will not read any voltage on the switch's open output.

An NC switch is the same as above but swapped in sense - ie, it will be GND with the door closed and floating (hence +V) when open.

NC switching is typically used for "fail safe" alarms and systems - ie, you know immediately if a switch or circuit has opened thru a fault or from something or someone cutting the wires. (For alarms you add series resistance and use impedance sensitive circuits to counter bypassing attempts whether shoring NC switches or cutting NO switches.)

The above however are not floating switches, merely floating outputs.
The resistive alarm input switch may be considered floating depending on where the resistances are placed AND what you define is "floating" ie, not referenced to a voltage except for thru 10M or 1M or 100k etc resistor/impedance. IE - "floating" in a circuit carries some definition of impedance; it may be 100 Ohm for a headlight or over 100k for an electronic circuit.

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