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Ok, got my head unit and metra kit in all fine and dandy, only everything has a slight, medium volume high pitch noise unless i turn the volume to mute. I've read up and i think i might need a ground loop isolator? what does that entail?
when i wired it i just wired the ground from the aftermarket radio to the ground from the metra kit wiring harness and I also grounded the "reverse" and "parking brake" wires to the same one. Maybe that's a problem?
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I'd check your grounds first because moving them around is free, but a ground loop Isolator will plug into the signal path between your HU's line outputs and amplifier. They generally have RCA connectors, so it's very easy to plug in.
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I ground loop isolator is basically a noise filter, and as such can affect the sound coming from your speakers or lower the output volume. While this is not always the case, it should be used only as a last resort. You should attempt to fix the problem, not put a band-aid on it. First, you should ground the parking brake wire somewhere else. preferable to a new, clean grounding spot in the body or dash of the car. (Not to a factory wire) It is preferable for the head unit to be grounded this way as well if possible, but not always required. The reverse wire usually requires a positive input, so you should also check your wiring on that one. Even if it requires a negative input, it should not be grounded to the same wire as your head unit. This is most likely the source of your problem. Do you have an amplifier installed? This could be another issue. A ground loop occurs when there is a difference in the ground potential of two separate audio components. In layman's terms this means that one ground is better than the other one. Since electricity always takes the path of least resistance, it will try to find a ground through your audio or signal wires to the better ground, thus creating noise, especially if the amplifier is driving your speakers as opposed to a subwoffer. Make sure that all of your equipment is grounded directly to a CLEAN chassis ground. This usually means cleaning the paint from a small area and drilling a hole in the chassis or body to make a good ground connection. There is one other issue that could appear if your car has a factory amplifier and you are trying to run it from a aftermarket (high level) signal. Did your car originally have a BOSE setup? If so, you will have to have this amplifier either removed or bypassed. The easiest way for a DIY'er to do this is to run new wires to each speaker. A professional can usually bypass it at the factory amp, but this is more involved, and requires more process than I can explain here.
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Last edited by Paradox_Racing; 03-29-2009 at 10:54 AM.
Heilander - first, disconnect the reverse output from the Metra kit from ground. This is a 12V output, and should not be grounded. Second, please describe your system - what's the head unit, and do you have an amp? Does the frequency (pitch) of the noise ever change? If so, it's probably alternator whine that can easily be filtered.
ok, first off, I dosconnected the reverse from the ground, so now its the head unit (DUAL XDVD8181) grounding to the ground wire from the metra kit, and also the parking brake wire.
i tried ONLY the headunit grounded to it and the noise persisted, might have been less, not sure.
anyways, no amp or anything yet, just stock bose. HOWEVER, I did run the RCA cable from the headunit to the trunk but it's not connected to anything (still gotta get teh power wire through the firewall and im lazy lately)
- anyone else's metra kit clock keep getting fast?
First, the side note. The firmware in the Metra kit needs to be updated - check the "Metra kit is out" thread.
I'm still not sure if you have an amp or not. "Stock Bose" probably indicates that your Dual head unit is driving the OE Bose amp, and that connection may be giving you the noise. It might just be a bad head unit. I would try connecting a speaker (find one in your house, anything) directly to the speaker outputs of the Dual unit. If you still hear the noise, it's probably the head unit. If not, there may be an amp in the car, and you need to work on a different way to connect to it. Does the head unit have low-level outs? If so, use those to drive the amp in the car (if you don't have an amp in the car, the result will be VERY quiet). The "Metra kit is out" also has some discussions on interfacing to the existing Bose amp. Good luck.
I am having this same problem, and I am almost 100% sure that it is due to the metra box. The reason I am sure of this is when I turn my HVAC controls on and then back off, the whine goes away for a while. It only seems to occur at low RPM and after getting jarred from going over a bump in the road. I have Kenwood DD unit with the metra kit (fw 1.4) and I did not bypass the bose amp, nor did I use my preouts adapted from RCAs to line outs. I grounded in the same manner as heilander, however, I did not ground my reverse wire. The parking and HU ground are shared I believe. no other changes have been made as of yet. Also, while I have heard of peoples clocks running fast, mine runs slow. its off about 15 min for every hour that my car is off. Please feel free to let me know I'm an idiot if I have done something wrong... not including the not bypassing the Bose amp and the grounding because I am going to split those grounds this evening... Always appreciate any help I can get from you guys.
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