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I know the easiest way to get rid of the noise is not to listen to the XM through the Autocom on the 09 LT....but there must be a simple way to get rid of it. Sure there are little boxes out there for $25 but inside that little box is probably $1.23 worth of the real fixit items. Anyone tore one apart yet? :wave
 

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Wrencher Extraordinaire
2005 K1200LT
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Some times you can eliminate it with a change in the routing of the feed wires to the autocomm unit. Keep them away from the alternator. I have yet to eliminate all of mine and I have built several filters that get most but never all of it. Mostly I have cranked the out put from the unit up and turned down the autocomm.
 

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shuster said:
I know the easiest way to get rid of the noise is not to listen to the XM through the Autocom on the 09 LT....but there must be a simple way to get rid of it. Sure there are little boxes out there for $25 but inside that little box is probably $1.23 worth of the real fixit items. Anyone tore one apart yet? :wave
I'm not familiar with the Autocomm, but as an EE I am somewhat familiar with electrical noise and it can be maddening to find. Two very common sources are improper grounding which can cause ground currents and induced noise through loops in your wiring, often the power supply lines.

If you ground to a point that has significant resistance between it and the battery AND is used as a ground path for other currents, then your ground won't be at the same potential as the battery negative, but will be at some higher voltage which is the product of the resistance of the ground path and the other currents that are flowing through it. This potentially generally varies over time as the current varies with other electrical loads that use this ground path. This can cause noise. The solution is to ground to a point at or near to the battery negative terminal.

Wiring loops pick up varying magnetic fields from things like spark plug leads. If you look at the inside of a cat 5 cable, you will see that the conductor pairs are tightly twisted. This is to minimize the loop area of those conductors and thus minimize the inductive coupling. If this is your problem, it can often be greatly reduced by tightly twisting your power supply conductor (12V) with your ground conductor. Twist as tightly as practical and as close to both the battery connection and the Autocomm as possible.

There are many other sources, but they can be hard if not impossible to fix (the so-called pin 1 problem, for example) so start with the common ones first.
 
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