FM Modulator grounding problem
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=14812
Printed Date: July 21, 2025 at 3:01 PM
Topic: FM Modulator grounding problem
Posted By: parody
Subject: FM Modulator grounding problem
Date Posted: June 12, 2003 at 5:42 AM
Hi All,
I installed a (Pyramid?) fm modulator in my Toyota Sienna, to get audio input from a dvd. I noticed that I was getting a high pitched whine when the engine was on, so I assumed I had a grounding problem.
I tapped into power from an auxiliary 12v jack, and grounded to a bare metal portion of the body. As I was fiddling around with it, I deliberately cut the ground wire, expecting the FM modulator to stop working. However, it did not!
It's obviously grounding thru the antenna wire. Is this FM modulator defective -- it's not supposed to work this way, right????
Thanks!
Replies:
Posted By: esmith69
Date Posted: June 12, 2003 at 8:15 AM
Actually it is supposed to work that way, but usually you need a better ground than just the one in the antenna. After cutting the grounding wire, are you still getting the high pitched whining sound? What year is the sienna, and have you tried one of these antenna noise filters? Finally, does the pitch of the whining sound change along with the engine RPMs? Or does it stay constant the whole time? ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: parody
Date Posted: June 12, 2003 at 10:27 AM
esmith69 wrote:
Actually it is supposed to work that way, but usually you need a better ground than just the one in the antenna. After cutting the grounding wire, are you still getting the high pitched whining sound? What year is the sienna, and have you tried one of these antenna noise filters?
Finally, does the pitch of the whining sound change along with the engine RPMs? Or does it stay constant the whole time?
Yes, it the whining sound changes with RPM's. It's a 2003 Sienna. I haven't tried an antenna noise filter.
I had my wife pick up one of these:
Ground loop Isolator
We'll see if that makes any difference. Otherwise, try a noise filter?
Posted By: esmith69
Date Posted: June 12, 2003 at 11:19 AM
The ground loop isolator could very well fix your problem. If not, also make sure the head unit has a good ground connection. And then the next step if it's still getting the noise would be to try one of these alternator whine noise filters. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
Donate to the12volt.com
Posted By: parody
Date Posted: June 13, 2003 at 6:17 AM
esmith69 wrote:
The ground loop isolator could very well fix your problem. If not, also make sure the head unit has a good ground connection. And then the next step if it's still getting the noise would be to try one of these alternator whine noise filters.
Yes, the ground loop isolator solved the problem -- no more whine!
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