Remote Start Constant +12V Source

I wanted to just get some feedback from fellow installers on this topic. I was discussing things with a buddy from work and we wanted to know what everyone else was doing for getting the constant +12V power source for a basic Remote Start and Keyless Entry. I usually use the constant 12V in the car's ignition harness unless it is listed below 50A then I will run the power straight from the battery...What do you guys do with your installs? When do you decide to find a new source for power? Also, on almost all remote starts the modules have 2 fused power inputs. Do you usually tie them together into the same power source? I have been doing this for the last 4+ years and never had any problems installing this way...Just wanted some opinions from everyone...

I usually always run the constant power to the ignition harness as long as the wire isnt a really thin gauge at the ignition harness.  If that is the case I will run it to the battery - I think i only did this on one car so far.  As far as tying the two wires together, I almost always do that, unless there is more than one constant power source at the ignition harness.  If there is two i will put one to each to split the load up.

I almost always use the ignition harness for my 12v source. I've used it in low-current systems like newer Caravans with no problems at all (I always use negative parking light connections in that case). As far as the two 12v input wires, they always get run separately to the power source. I never combine them except at the connection point, if they're both tapping into the same wire.

Me too, always the igntion harness(even caravans) with no problems. With todays new ignition harnesses that are lower amperage, it a matter of using everything low current(like parking light negative). Most alarm/RS run on well below 5 amps(including siren), not enough to justify another power source....Mike M2

Tech Manager

CS Dealer Services

Through experience these are the rules I followed, with a few exceptions, but none the less a good rule for some of you beginner and DYI. Honda one constant +12V white power wire. Acura one constant +12V white power wire. Toyota two constant +12V. Nissan one constant +12V Green power wire. GM two constant +12V RED. Chrysler one, on new model, run power from the battery 10a will do. Ford two +12V. Mazada old model one, new model two. Subaru one +12V Suzuki one +12V Mitsubishi one +12V etc.... Be careful whose advice you buy, but be patient with those who supply it.

A remote starter is designed to duplicate what you do by turning the key in the ignition cylinder. If the ignition cylinder has two battery feeds then you MUST hook the remote starters battery feeds to both. Manufacturers aren't in the habit of adding extra wire to their systems for no reason. Many vehicles require a large amount of current to power all their systems and accessories. To do this safely, they split the current load into two circuits that are each rated to carry the required maximum current. If you don't duplicte this with your remote starter you can cause serious damage to occur. Sure the vehicle starts if you don't do this, but check the wires and connections a year later. I will bet that they are damaged from heat build up because they are being overloaded. On modern vehicles, computers and modules are very sensitive to voltage dips and spikes. Finding a good source of power is more important that ever if you want things to work as they are supposed to. New GM vehicles only use the ignition wires as a reference to the BCM and can't handle any current. Take it from someone who has seen the bad results of incorrect installs too many times. Do it right or not at all. When in doubt, run a fused line off the battery. It is usally safe to use a 10 or 12 gauge wire in the igniton harness for power. If there are two use them both separately. Don't forget to install separate fused lines for other items like bypass interfaces. Don't fuse them off the 30 amp main circuits. The thin wire most of these items use will burn up and cause a fire long before the 30 amp fuse blows. If any of my installers don't do it this way, they get one warning and only one. After that they are gone. This is one of reasons why in parts of Canada you must have a government license to install alarms and remote starters.sparky

Some really good points here spackie. "This is one of reasons why in parts of Canada you must have a government license to install alarms and remote starters." Even the guys you mention above who know the standard procedure requirement don't all do it, but indeed a good rule to followed and practiced as you suggest. Be careful whose advice you buy, but be patient with those who supply it.