I have a question about the 12V switched ignition wire coming off of the factory harness and I wondered if anybod had any ideas? I installed my stereo system w/ Metra NIRD-01 interface. I attempted to hook up my PAC SWI-PS, but the PAC unit had a short in it and had to be sent back. I've got the replacement unit, but I noticed while trying to program it that when I turn off the car, that the PAC unit still is getting voltage. I pulled out my voltmeter and started probing wires. I'm getting 5-13mv at the 12v switched wire (at the PAC adapter) with the car off. The voltage goes to 13.8v when I turn the car on. I called PAC and apparently this 5-13mv is enough voltage to keep the PAC unit from turning off. I started probing backwards and I'm getting 5-13mv at the H/U with the ignition off, and at the NIRD interface with the ignition off. I probed all of the way back to the factory radio harness, and it also shows 5-13mv with the ignition off. Is this normal, or should it read 0v with the ignition off? I'm wondering if I have a problem elsewhere?
Here is my install thread if you need any other info:
http://forums.maxima.org/audio-elect...m-install.html

PAC told me to install a relay, but nobody seems to be able to tell me at what voltage a relay will trigger/release. I don't want to install a relay if the 5-13mv that the line is seeing with the ignition off will cause to to "trip". Any help/insight here would be greatly appreciated. I posted this question on a car audio forum, and they're saying I have a problem that needs to be fixed. I don't have any ideas at all on what to check that would be causing a "bleed-through" on the factory harness?

 

does the voltage trickle cause an issue with your HU? if not, power the PAC unit straight from your ignition switch.

Did you try unplugging the Metra piece and reading?

 

Yes, I traced all the way back to the factory harness, and I still get a small trickle. The head unit does not power on without the key on, so it DOES NOT affect the head unit. PAC tech told me if I picked up the 12v switched from the ignition, that it could cause problems with the unit. I don't understand why, but that's what they told me.

 

I can't imagine why it would make a difference where you grabbed switched power - its a standard ignition switch. If you need 12v switched, try it there, or an accessory (at the switch) should work as well.

If you ever get them back on the phone ask them to explain why there would be problems from hooking it up directly.. Ive never had an issue doing this

 

this is just an idea, but worth a shot....what if you installed a pull down resistor

maybe take a 20kohm resistor and wire it between the 12v switching power and ground

 

Sorry, now you're talking WAY over my head

 

http://en.wikipedia.org/wiki/Pull-up_resistor


If the PAC needs to be 0 volts and you have .whatever coming to it, a way to bring that voltage down to zero would be to essentially ground the power wire but obviously you cannot do that since that is a short circuit and your PAC will never get power that way, but if you ground it indirectly, via a high value resistor then the low voltage when the car is off should be dragged to zero and when there is 12 volts on the line that value should not change because the resistor has a high value. Also you could install a diode, since diodes have a bias voltage of .7 volts.