Ground Loop Problem in 97 Yukon
Thread Starter
Safety Car
Joined: Dec 2001
Posts: 4,832
Likes: 0
From: Florida
Ground Loop Problem in 97 Yukon
I just had a system installed in my 97 Yukon. After the install, I noticed a slight ground loop/hum. I took it back to the installer, he added a noise suppressor which seemed to work. About a week later the hum came back. It's odd that it happened right after serveral days of rain. After the weather dried out, the hum went away, but now it's back. My question is, has anyone had any luck with changing their spark plug wires to remove noise in a radio? Any other thoughts are welcome.
Thread Starter
Safety Car
Joined: Dec 2001
Posts: 4,832
Likes: 0
From: Florida
The system has a Alpine head unit and a 4ch. MTX amp, so yes there is a good size power cord coming from the battery. I've check the ground on the amp and its tight, metal on bare metal. Thanks
Le Mans Master
Joined: Sep 2002
Posts: 8,991
Likes: 2
From: Hanger 18 Taxachusetts
Just a guess but if it is grounded to the body, maybe it is being partially isolated thru the body mounts?? When it rains the water interfers even more??
Maybe try to lengthen the ground wire to a point on the frame to get a true solid ground??
Maybe try to lengthen the ground wire to a point on the frame to get a true solid ground??
Race Director
Joined: May 2003
Posts: 14,137
Likes: 2,984
From: Iowa
St. Jude Donor '03 thru '26
That is your best bet 
Chances is that it is a grounding problem. One way to troubleshoot this is to unplug the RCAs going to the amp. (always unplug/plug-in) RCAs with the power off to the stereo). Turn the stereo back on, if the noise is gone ,you have a hum coming done the RCAs. I don't think is the case though and you will still have the hum.
If you do still have the hum, relocate the ground AND to run an extra ground to the chassis from the negitive to the car's chassis. The best way to fix the problem is to run the ground of the amp to the negitive of the battery. Be sure and use the same guage wire as you did for the power wire. You will have ZERO noise like I do
Chances is that it is a grounding problem. One way to troubleshoot this is to unplug the RCAs going to the amp. (always unplug/plug-in) RCAs with the power off to the stereo). Turn the stereo back on, if the noise is gone ,you have a hum coming done the RCAs. I don't think is the case though and you will still have the hum.
If you do still have the hum, relocate the ground AND to run an extra ground to the chassis from the negitive to the car's chassis. The best way to fix the problem is to run the ground of the amp to the negitive of the battery. Be sure and use the same guage wire as you did for the power wire. You will have ZERO noise like I do
Advanced
Joined: Jun 2004
Posts: 75
Likes: 0
From: San Diego Ca
Another thing to look for, is to make sure that the RCA cables and the power wire are not running along the same side of the truck. They need to be seperated as to not get esd in the RCA cables. So try that and good luck.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
great suggestions, all!
I run my power down the same side as the battery. You don't want the power crossing the car, because it can pick up noise that way.
Another thing, check the RCAs themselves. If the metal ends are touching, you can pick up a hum.
Finally, check the "gain" setting on the amp. If it's too high, then the amp will pick up and amplify noise. Many Alpine heads have 4V outs, so they will be less prone to picking up this kind of noise.
If nothing else works, you can get a preamp line driver. It will boost the voltage to 16V!!! Serious! This will allow you to drop the gain on the amp to nearly nothing. And all that voltage will act like a force field, keeping the noise away.
I run my power down the same side as the battery. You don't want the power crossing the car, because it can pick up noise that way.
Another thing, check the RCAs themselves. If the metal ends are touching, you can pick up a hum.
Finally, check the "gain" setting on the amp. If it's too high, then the amp will pick up and amplify noise. Many Alpine heads have 4V outs, so they will be less prone to picking up this kind of noise.
If nothing else works, you can get a preamp line driver. It will boost the voltage to 16V!!! Serious! This will allow you to drop the gain on the amp to nearly nothing. And all that voltage will act like a force field, keeping the noise away.
