Door trigger, 2005 Ford F-150

I was thinking about that exact pictorial somatic to block the excess back voltage I'm glad you pointed out the RAP problem that it creates   I have a question where o you get the picture diagrams like you had just posted is that something I can buy and add to my collection of stuffMatt

Either by searching the forums on this site or varied key word google image searches. No direct source as of yet just a lot of work and from memory. Sometimes my memory gets a little fuzzy and have to refresh it. Would be nice if there was a searchable repository like that to search from.

Since I know nothing about F Series might I ask if the door switches are open circuit when the door is opened? How's about wiring to the domelight and disabling the door ajar warning.

No they are not open circuit they are 0v (ground) when opened. the problem with the dome light is the 30 second off delay. Most people don't want to wait for the light to go off so they can arm the alarm. So it doesn't give the second bypass chirp. I have heard of wiring a relay in to disconnect the negative trigger input wire while the dome light is on using the ground when armed. The BCM controls the door ajar, dome light, and RAP shutdown from the door triggers. The driver door and all other doors are indicated ajar separately.

OK turning the pair of diodes around worked now the alarm does not go off when I try to remote start the truck I wired the constant 12vdc on after the fuse for the viper system in case I get a direct ground short it does not blow a fuse in the truck that has something to do with safety or functionality. Do you think I should draw out a scmatic of the finished product so someone else can use the help Again thanks for all the help guys mattMatt

All +12v feeds should have a fuse even if it is shared between multiple low draw relay coils and the like. Sure that what this site is about I help you you help someone else, basically pay it forward.

lurch228 wrote: Typically this happens when the BCM sends a negative pulse to the doors. You will need to wire +12v thru a 10k resistor to the alarm (-)trigger wire after the diodes to bias the alarm (-) trigger so negative pluses can't deliver ground to set off the alarm, only a constant or longer negative trigger will drain the (+)bias to ground. The only other way is to diode isolate the BCM from the vehicle door triggers which also stops the RAP shutdown and the dome light from working.

@lurch228 I recently did a 2004 Chevy Tahoe with a similar predicament. I installed used a Prestige 997E with an Flashlogic bypass and during a remote start, the alarm would go off. Tech support said other installers had run into a similar issue and the cause was at the BCM. Would this have fixed it? I confirmed via the key fob that it wasn't the trunk or hood pin being triggered. I ended up setting the 997E to Unlock before & Lock after start to bypass the issue.

Yes on the Ford f150 the bcm sent out a negative pulse to make sure the dome light is not on and the alarm system thinks the door was open so placing the resistor in the circuit as shown above creates a filter for the quick check that the bcm does it also have a very small delay when the door is actually open but it is almost negligible because the the actual ground conductivity between the two is much larger when the the door is open to when the bcm sends out its pulseMatt

These are 2 different issues. This is a Ford BCM design function checking issue, From what I know yours is a factory alarm (security function) needs to be disarmed to remote start by unlocking. I haven't and don't know of anyone who has tried to do this on a Tahoe to see if it would work or not. With the Ford it's setting off the aftermarket alarm, not the OE alarm.