Now I am really confused!!Diode or relay

okay, let me explain this again.  I hooked the scanner up as follows, red-posative 12v/ black to chasis ground/  yellow to - output 500ma accesory when armed on the rattler 300.  as instructions said.  The scanner will work normal while engine is off( flash patterns), but when I start the car the scanner stays lite no patterns.  I tried hooking it up to a 12v wall adapter, and squeezed the yellow wire with my fingers and the snanner would remember the last pattern, and when I let go of the wire it would opporate as it should.  So does this clarify what I should use relay or diode?????  Sorry for being a pain all, but I am learning. THANX

Ok here it goes,
red wire to constant positive.
black wire to ground.
yellow wire to ignition.
Your having a problem with the installation because your orange wire from your alarm only supplies a ground when armed.. The led need to have a positive in order to completely turn off. When you turn off your alarm the orange ground when armed does not turn into a positive so thats your problem. Simply wire the yellow wire to your ignition, that way every time you turn off your car, it will automatically turn on your led and it will always remember your set pattern. Got it!...good luck....I sell the vs400led for $15 if you are interested in getting more...

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hi alarmpro, thanx for the info.  I just tried hooking the yellow wire straight to the yellow + ignition input on my alarm, but there was no change the scanner still  just stays lite no pattern, and when I turn the car off it will opporate as it should, but not with the alarm controls