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Add rear defrost feature using an Avital 4103 on a 2002-2005 dodge neon

Add rear defrost feature using an Avital 4103 on a 2002-2005 dodge neon

September 14, 2015 9:14 pm0 comments

What you’ll need:

Hey Everyone,

After much searching I could not find a good how-to guide for adding the rear defroster feature on my wife’s remote starter (Avital 4103). I installed the remote starter a year or so ago and figured I would come back and add this “simple” feature later. As far as I could tell, I just needed to connect the H2/5 Blue/White wire to the right defroster wire and I was all set. Well that was not the case.

Background: If you didn’t do that install yourself, you’ll want to read up on the installation guide and manual. What you’ll find is that there is a blue/white wire on H2/5 port of the remote starter that can be programmed to do 3 different actions:

  1. (default) creates a 200 mA connection to ground that disconnects when the remote starter turns off. 200 mA is that max, because that is all the transistor can handle. So use a fuse! Note: This does not put out a voltage. It just creates a circuit to ground that can support a max current of 200 mA.
  2. The same as #1, but it creates that connection 10 seconds after the remote start. This connection lasts 10 minutes or until remote start is turned off (i.e. you get in the car and drive away).
  3. Sends a quick 800 millisecond pulse to ground 10 seconds after the remote start happens.

Ideally you want case 3. You want a defroster unit that will trip with a ground pulse. Unfortunately, the 2005 (and I assume 2002-2005) neons don’t allow this using any of the wires normally coming from the unit. So here is what I did to get around this:

  1. Remove the radio/HVAC/defroster cover.
  2. Unscrew the defroster unit and pull it out.
  3. Using a flathead screwdriver, pull the defroster relay unit out of the defroster/cigarette lighter/storage unit.
  4.  Pull the black case off the back of the defroster unit (i.e. the unit with the button on it). Here you will see the circuit board for the relay.
  5. Find the button that trips the defroster relay. The actual button you normally push just pushes an electronic button on the circuit board. This electronic button is the button you want to find. It sticks off the circuit board and has a little circle button on it.
  6. Once you have found it, start your car and press the electronic button with your finger to make sure it works. If it work, continue on.
  7. Now we get to the fun part, basically want you are going to do is use the relay you purchased to trip the defroster relay. Here is a schematic:IMG_20150914_213255_942Basically you want to connect:
    1. #86 pin on purchased relay to the H2/5 blue/white wire on the Avital 4103.
    2. #85 pin to a constant 12V source. You can get this from anything (e.g. a direct connection from the battery), but I went with the hot pin in the Red 4-pin port on the Avital unit itself. I wasn’t using a bitwriter (i.e. remote start programming unit). So it was unused. Additionally, I also connected my fuse holder/fuse and toggle switch in this circuit. Note: I added the toggle switch because then I can shut off this feature in the summer to prevent my glass from exploding (you could do this by programming the remote starter too I just found this easier) and I went with the fuse holder to prevent my avital unit from seeing too much current on accident.
    3. #87 pin you’ll want to solder to one side of the switch on the backside of the circuit board. Complete step 8 first!
    4. #30 pin you’ll want to solder to the other side of the switch on the backside of the circuit board. Complete step 8 first!
  8. Now you’ll want to cut away the plastic on the defroster relay case so that the backside of the electronic switch is showing enough to be able to solder to the points. You’ll want to solder to the switch pins after you put this plastic cover on, because there is not much room in there to run wires.
  9. Once you have that complete, plug everything in, program the Avital menu 2-feature 8 to option #3 (i.e. Pulse 10s after start), and then test the system to make sure it works. The pulse should trip the relay you purchased which will trip the defroster relay. The defroster relay has the timer built in to keep the current flowing to your defrosting elements.
  10. Reassemble the defroster unit, the radio/HVAC cover, and then hide all of the wires/toggle switch in a convenient place

That’s it! It turned out to be way more of a project than I was expecting, but I hope this guide helps. Ideally I would have more pictures to help you along the way, but I didn’t take any so feel free to comment below or email me with questions.




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