convert ground when closed triggers

oldspark wrote: Aren't your door switches normally open - they only close with the door open? That's what the DEI techtip refers to. Use a normal relay; there is no drain unless a door is open (and BCM etc is active). And re that TechTip 1921 diagram, I don't see why ONE 10k (or 1k) resistor from the (+) Door trigger input to +12v fused isn't used instead of its four resistors...

My question is about normal closed factory hood and trunk triggers and negative triggers for the alarm system. I don't understand how a normal relay can be used with the TechTip.

NO RELAYS!! You will drain your battery. Just use a DTI Mazda on each.

howie ll wrote: NO RELAYS!! You will drain your battery. Just use a DTI Mazda on each.

The triggers for hood and trunk are negative. You mean connecting to positive door trigger?

No the DTI Mazda simply converts the normally closed circuits to the more common type normally open, pos. trigger, just use that as explained above for the doors.

sam369 wrote: My question is about normal closed factory hood and trunk triggers and negative triggers for the alarm system.

The tech tip says "Some vehicles have door triggers that rest at ground when the door is closed..."- ie, Normally Open switches that are GND whe the trunk/door is open. That DEI TechTip is not applicable to +ve triggers nor NC door/trunk switches. If you do indeed have "triggers are ground when closed" switches (which IMO are generally not used in vehicles), then you'll need a FET to turn on the relay, or a transistor if a small drain of typically under 1mA is acceptable. Using a relay means it is normally energised and thereby its coil drains the battery, but DEI TechTip 1921 has nothing to do with that.

oldspark wrote: sam369 wrote: My question is about normal closed factory hood and trunk triggers and negative triggers for the alarm system. The tech tip says "Some vehicles have door triggers that rest at ground when the door is closed..."- ie, Normally Open switches that are GND whe the trunk/door is open. That DEI TechTip is not applicable to +ve triggers nor NC door/trunk switches. If you do indeed have "triggers are ground when closed" switches (which IMO are generally not used in vehicles), then you'll need a FET to turn on the relay, or a transistor if a small drain of typically under 1mA is acceptable. Using a relay means it is normally energised and thereby its coil drains the battery, but DEI TechTip 1921 has nothing to do with that.

Sadly, what are generally not used in vehicles are used for Ford Fusions.

So use a relay & diode if needed, or transistor, for the Luggage Compartment and a transistor for the Anti-theft switch or swap its GND output to #2 and use an NC (SPDT) relay to GND the "hood ajar" line.

oldspark wrote: So use a relay & diode if needed, or transistor, for the Luggage Compartment and a transistor for the Anti-theft switch or swap its GND output to #2 and use an NC (SPDT) relay to GND the "hood ajar" line.

Transistors are quite new to me. I haven't figure out which kine to use and how to wire it up. If I connect Gate to factory hood or trunk trigger wire (ground when not triggered), Source to vehicle ground, Drain to alarm trigger input, which kind resistor can break the circuit when Gate get ground? If I use one of this kind of relay for each trigger, is it a concern 25 mA drain when car is off?

I mentioned that the trigger wires read +12v but cannot power 12v relays when hood or trunk is opened. Maybe they can be Gate input to close the circuit (n-channel enhancement)?

New to you? You nailed the (MOS)FET wiring!! The only additions - a 1M or 100k resistor from Gate to GND (assuming an N-ch FET) to ensure it turns off (it's too easy for the Gate to get its nA from floating outputs, so pull it down to GND). And add a pull-up resistor (10k? 100k - but significantly smaller than the Gds (G to GND) 1M etc resistor) if the trigger input is is foating etc (not normally "hi" = +12V). A series resistor between the source (switch) and Gate is often added but that's usually to protect the source (switch) from overcurrent in case of FET breakdown, but that's usually irrelevant for switches. (Sorry about "source" vs FET Source... maybe the latter should be referred to only as S?) However I'd prefer to swap the Hood Switch's #1 output to #2 so its GND is only connected when the Hood is open. Then add a normal car SPDT (changeover; 5-pin) relay to disconnects its 30-87a between GND and the HOOD AJAR #10 C2280F input. Otherwise the FET can drainlessly invert the standard OEM wiring/signal. There is no "resistor" to break any current. Only the relay, else as above for a MOSFET.