On my remote start system there is one accessory output, but our cars have two accessory wires to tie into. I want to know how to wire up a relay to take care of the second wire. I was thinking that i could just use the 12v that is powering the first accessory (coming straight from the remote start) wire as the turn on to flip the relay into powering the second accessory wire. The reason i'm doing this is because as of now when my car is in remote start mode, only the fan turns on for the air conditioning, the compressor itself is powered from the second accessory wire... TIA

 

relays are easy to do if you break them down into their seperate parts, the coil and the switch.

The output from your remote start is probably going to be a negative output to control your relay. This means that when it wants to turn the 2nd ignition on, it will put a ground pulse on that wire for as long as it wants it on. If we connect that wire to one side of the coil(85 or 86, doesn't matter), we will need +12v constant on the other side in order to activate the coil. So if you connect the alarm output to 85, connect +12v constant to 86. Now you will need to finish the other side to get the power where you need it. There are 3 contacts for the switch. One conact will connect to both of the other pins depending on when you want power to turn on or off, this contact is #30. When you hold the relay in your hand and the coil is not activated, #30 is connected to #87a(this is the normally closed part of the switch). When you activate the coil(you will hear it click) then the #30 is connected to #87(this is the normally open part). You will normally only use two of the pins unless you are wiring a 5-wire doorlock(one of the more difficult types and more common on mustangs). In our case we will want to use the #30, and the #87 since we want to turn something on. With these two contacts you will want one side going to +12v constant(yes it can be from the same place as the constant needed for the coil as long as it can supply the current needed to drive the circuit we turn on) and the other side will connect to your vehicles 2nd ignition wire.

So to recap
85 - +12v constant
86 - your remote starts 2nd ignition output
87 - +12v constant
30 - to your vehicles 2nd ignition wire

The pin#'s are located on the bottom of the relay. Be sure to use it properly to prevent forest fires and get your pet spaid or nuetered........

 

Thanks ttocs, i got it all figured out and working. now for my next question. I still have a few unused channels on my alarm system so i was trying to rig up the windows, one channel would roll them up and the other would take them down. I just went into the window switch on the drivers side with my meter and started testing the wires seeing what powered what. I found the wires that control each window motor in each direction and wired it up with a relay from my alarm. In the 12v constant i had wired to the relay i put a 30A fuse, but everytime i went to test the windows by remote, they would move a little bit, if at all, and then it would blow the fuse. This seems like such a simple thing to wire up, i double checked all my wires and couldn't figure out what i was doing wrong. Is is possible that the combination of both the window motors pull more that 30A?

 

ford like to use 5-wire systems in their windows as well(the switches do all the work of the relays saving parts). To properly wire into these systems you need to diagnose which switch is the masteer switch and which is the slave. When using the relays you would need to use all 5 points of the relay including the 87a(normally closed contact). Improperly wiring them up will cause blown fuses or worse........

They make window modules for just this use that makes things much easier, neater and safer as they have current limiting to stop the window in case something is stuck in it.

 

Darn i guess it isn't as simple as i had thought. I'll have to do some more research before i can tackle that job.