hello everyone, thanks for reading.
a little background. we have a 2004 gmc yukon xl. if it is left to sit for mored than 1 day, the battery will be drained enough to cause a no start the next time needed. after some investigating, i found that the cause is a relay that was installed for the aftermarket alarm. there is a prestige A786 alarm/ remote start installed. there are two modules installed, one for the passlock, and one for the door lock interface, the door lock is numbered 456G, i foget the brand name. this module has a relay that puts +12 volt to a grey w/ black trace when the doors are opened causing the alarm to sound. this relay gets power from the battery, and gets it's ground from a grey w/ black trace found in a connector under the sterring column. this wire is ground when the doors are closed then goes high when the doors open. this means that the relay is powered all the time the doors are closed. which puts a 140 ma draw on the battery( the draw of the coil for this relay) when the doors are opened it removes the gorund from the relay, the relay changes state and provides +12 volts to the 456G door trigger wire.
my problem/question, is ther another way to get +12 volts to this input when the doors open without having a relay energized all the time. at the present time, i have removed the relay so there is no door trigger on the alarm(no big deal to me at this time) i still have the "shock" sensor installed, so if anyone tries to get into it, that will activate the alarm. it would be nice to have a fully functioning alarm though if this is the only way of connecting i will do with out the door trigger.
another issue i found while trouble shooting this, if the switch on the dash to disable the interior lights is pushed in, the alarm will never see the +12 when the doors open(kinda defeats the alarm) so, i neede to find a new way of activating it anyway.
with the relay removed, the alarm has a 16ma draw, which puts the total draw on the battery to about 30ma. that is alot better then the 170ma i found when i first started this endevour.
thank you for reading, and thanks for any help you can provide.
Lee
According to the manual, the purpose of the gray/black input wire on the 456G is to convert the positive dome light from the vehicle to a negative trigger for the alarm. Most alarms have both positive and negative door trigger inputs. Unfortunately I can not find a manual for the A786 (are you sure this is the right model?) to verify what the positive door trigger input wire color is.
As you have already pointed out, when you turn off the dome light the positive trigger goes away, which kills the alarm's ability trigger when the door is open in your current configuration. With that said, there is a way to get the alarm to trigger with the doors regardless of the position of that switch, but it is a significant amount of work compared to that single wire hookup. In the driver's door there is a gray/black wire, in the passenger door there is a BLACK/ white wire, at the BCM there is a purple plug with a lt. blue/black (at pin A3) and a lt. GREEN/ black (at pin A2). These wires are the individual negative door triggers that operate regardless of the position of that dome override switch. If you go this route you would need to diode isolate those four wires and connect them to the alarm (you can find more information on this by searching this forum).
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Installer, IT support, and FFL. I need less hobbies.
Twelvoltz wrote:
In the driver's door there is a gray/black wire, in the passenger door there is a BLACK/ white wire
Doesn't the 456 output (via databus) the front 2 doors on the green wire?
I thought so too. But the poster requested how to hook up the door triggers without using the 456G, as he has determined the door trigger using the 456G is causing a significant draw. And if you look at the manual for the 456G it states
"GRAY/BLACK (+) Door Trigger Input: This connection is
only necessary when installing a security system. The
GRAY/BLACK wire should be connected to the under dash
light wire that tests (+) 12 volt when a door is open (see
diagram). When this wire receives a (+) 12 volt input, the
GREEN wire will send a (-) output to the security system,
except during Dome Light Bypass mode.
NOTE: The 456G converts the GRAY/BLACK (+) door trigger
input to GREEN (-) door trigger output internally."
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Installer, IT support, and FFL. I need less hobbies.
well i made a slight mistake on the model number. the alarm is a Prestige APS786T. it does have a negative door trigger, but i thought it needed the 456 for some reason. though i cannot recall the reason. the draw is actually from a relay that is connected to a grey w/ black trace found under the sterring column. this relay is how the 456 gets a +12 when the doors open.
if i use the negative door trigger from this same grey w/ black does the 456 stiil need to see +12 when the doors open?
thanks again for the help.
Lee
I would get a better module. The newer ones allow selectable inputs, like the GMDL-BP. They also read the databus for front door trigger, so you don't have to go searching for the domelight output.
I know that's not what you want to hear, but that may be the only way to avoid using a relay.