ok, so when i was 16 and got my start workin on cars it was doing radios and electronics, and i learned most of what made me really good by coming to this forum. I learned a LOT of stuff from a guy named Jason Carol, dont know if he's still here. I have an electrical problem that i cant figure out, and i thought why not go back to where it started, and see if anyone on j-body could help me out on this.

I drive an 87 camaro with a built 350 motor in it, meaning it's got a blaster 2 coil and super conductor wires, that might come into play in this problem. I just bought 2 xm radios and subscriptions for me and my girlfriend, but hers is for her birthday next week so i cant try swapping parts to see if anything fixes my problem. now, when i have my xm hooked up either with the car running or not, i get a heavy whine and a tone over the signal through my speakers using a 3.5 headphone jack wire that plugs right into the front of my radio from the output of the xm piece. ive hooked it up in another car with a pioneer deck and same front input, it ran great. I also used the tape adapter in another car and it worked great. if i use the fm modulator function of the xm reciever then it doesnt come through clear at all on the radio station, but if i take the 3.5mm jumper cord and wrap it around the xm receiver the signal sounds great!

so, i started thinking, maybe the noise im getting is because something is either wrong with my antenna or cable, or something is wrong with the radio and it's causing it to use my input cable as an antenna feedback. i thought maybe the wire was just a way for the xm to put out a stronger signal, so i unplugged it from the car's radio and the signal dropped again. it was definately related to being plugged in.

i measured resistances of the antenna, from behind the radio there's no connection from the antenna cable's inner contact and the outer shield, as it should be. from the outer shield to ground is .02 ohms, which is the max spec according to my general motors service information source, and the inner contact to the antenna mast is .05 ohms, which is technically 2 and a half times the correct resistance. so the antenna is in question, just dont know if its enough to cause the problem.

so i was thinking, if you can get a ground loop problem between your radio, being the signal source, and an amp, being at a different ground location, then maybe my xm having it's own power converter and sending an audio signal might have enough of a ground difference to somehow cause a ground loop noise. so i went to work with my new Fluke 87-5 multimeter and measured voltage drop, or voltage differences at several ground points. before starting i knew my cigg. lighter was all rusty so to eliminate that bad contact as a cause for the problem i took i apart, sand blasted it and then blew it out, put it back in and tested it. so, from the cigg. lighter ground to the radio's body ground is a difference of 0.01v, not very much. the voltage drop from the actual plug going into the radio receiver, (remember, it went through a power converter at the lighter port), is a difference of 0.02v.

I am pretty sure i read somewhere that a cheaper audio system will commonly use the radio ground as a return on the audio signals coming in and going out of the device, and that nicer equipment has the signals ground to a chip where the signal originated, also known as a low reference. i was thinking, if this Aiwa brand head unit uses a cheap radio ground on an incoming signal that's probably not even 3 volts max, and my lower end delphi xm radio does the same thing back to it's power converter, is that a possible cause of this noise, and maybe i should shell out the cash for a new alpine radio (the only brand i trust for head units)?

I dont think it's related, but Ive got a JBL p360.1 amp pushing two alpine type-s 12s, i unplugged the RCAs to the amp and still had the noise

Spark plug wires.


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Aiwa = crap head unit... probably the source of your problems.

Don't sweat the resistances.... your leads probably have 0.1 ohm resistance to begin with

Plug Wires not an issue when the car isn't running. Just my .02

yeah i was thinkin the HU could easily be the problem, but because this car has given me nothin but trouble since day 1, im hesitant to buy another unit and find that it wasnt the problem. I know Aiwa is junk, and i definately wouldnt have bought it, but it came out of my girlfriends wrecked car and i needed it for the front mini jack input. anyway, yeah the wires may be a heavy concern once this engine-off noise is gone. i noticed some low level alt. noise yesterday under the heavier noise, which i am assuming is a ground loop problem with the signals.

i guess step one is to swap head unit... but i just spent ALL my money (literally) in the last 3 days. i actually bought a j-body, you guys would be proud

i got an 04 cavi that has a blown motor. the timing chain guide broke, chain started jumping around like mad, bent valves sideways, released rocker arms that got bound up in the cam lobes, broke all kinds of stuff, coolant in the crank case.... anyway, i pulled the motor last night and my new one should be here today. got a 2.2 from a grand am that only has 8 thousand miles on it! woohoo! now i can actually be a j-body guy for reals

p.s. that car could be yours for 4500, the car's got 67 thousand miles on it, no trans leaks, automatic, manual windows

its either the HU or the mini jack wire....is it the 99 cent wire? you probably need a better quality wire......

yeah spark plug wires shouldnt be an issue if its happening with the car off. i likely to go with the above and say its either the radio or the wire. if you have the exact same unit for your girlfriend, and dont want to spend money i'd say wait till you put hers in, and then you have something to compare and swap in and out. next id try finding a better wire, then the headunit.


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if you know how and can do so without destroying anything, try grounding the aux plug on your CD player straight to the chassis.

yeah i was definately going to try swapping parts with her setup after i give it to her.
as for the wire, i tried 2 different wires, one is belken and one is radioshack. same result with both.
as for the chasses ground, i actually think thats what is causing the issue, so its not something id really wanna try to create if it's not already in action.

woops, didnt see the car off thing.


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Do you have the same problem if you plug other devices into the aux port?