QuestionQUESTION: ok i have 95 jeep grand cherokee and i put a new stereo deck in it and a amp and subs. the amp and subs arent the problem because they sound great. the problem is when i turn it up i get to about its half way mark and i start to hear a crakling or fuzzy sound almost like when your on a radio station that isnt a station. at first i thought it was the speakers so i bought some brand new power acoustics and i hooked up the first one and it didnt fix the problem. what could cause this im thinking it would either be my head unit cant drive the speakers at a louder noise but its only at half way so it should be able to the only other thing i could think of is if i maybe have a ground problem somewhere that is hitting the body when i turn it up and is causeing the static. my rca cables to my amp for my sub are on the opposite as the power cable is and when i was trying to figure out the problem i would disconnect the rca cables from the amp so i was only listen to the speakers do you know what could cause this problem thanks
ANSWER: Hi Brian,
There are a few things I'd check regarding your noise problem.
First of all, make sure your new head unit is grounded properly. There's no ground wire in the factory radio plug for your Grand Cherokee; the original ground wire was probably either a separate wire or mesh grounding strap, connected directly to the factory radio chassis. Your new head unit's black ground wire should be connected directly to the factory ground wire, not to any wire in the radio plugs.
Second, there's a very good chance your Grand Cherokee is equipped with a factory amplifier. You can check by looking under your rear seats. A defective factory amplifier might be the source of your problem, but it's unlikely if you weren't getting the noise when the original factory radio was in place. However, if you're planning to replace the original speakers, you'll want to bypass the factory amplifier in any case.
Third, you should double-check your speaker wiring behind the head unit. If you've mixed up the speaker wires, the result could be lots of distortion when the volume is increased.
I doubt very much that the amplifier, amp ground, or RCA's are part of the problem. It sounds like an integration problem between the factory amp and the head unit, or the head unit and the speakers.
Hope this helps!
Brian
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QUESTION: well there wasnt the factory stereo or speakers in it when i first got the cheorkee it had a durraband deck in it that sucked and when that deck was in if i turned it up to loud it would just turn off so i thought that it was just a faulty head unit so thats when i put it all in. As far as i could tell there is no stop amplipher in it or at least if there was they took it out before i bought it. there was no wiring harness from the factory stereo just a bunch of wires pretty much a big mess but i found a list on the internet telling me what wires were what so all the wires should be hooked up right ill try fixing the ground to see if it helps by making my own ground just to test it. do you think that if one wire going from the head unit to a speaker was rubbing on the body it could cause the static and distortion in all 4 of the speakers. thanks
AnswerBrian,
Yes, a grounded speaker wire could definitely cause the problem. There might be a pinched or shorted wire at one or more of the speaker locations. Usually a head unit will have a protective circuit that will shut off the sound in this case, but if not, the result will be an overloaded amplifier and lots of distortion on all the speakers. Eventually it could damage the head unit's built-in amplifier.
If I was troubleshooting the issue, I'd start by using a multimeter at the head unit location, and test each speaker wire for continuity with chassis ground. I'd also test the resistance between the positive and negative speaker wire of each speaker; a reading below about 3 ohms might mean a defective speaker, or one speaker wire shorted against the other.
Good luck!
Brian
