Jims79

I installed a new in-dash CD player in my son's truck. The CD plays great the radio sounds good until the motor is running that I get noise on both AM & FM but not the CD. I tried a new ground and swapped antenna but still engine hum on the radio. Any fix's I can try.
Thanks
Jim

JoeRags

you need ignition shielding... or just listen to cd's

Durango_Boy

There is a ground loop and interference from the alternator. Is the stereo hooked up to the factory hot and ign. wires? Something that helped me was to run the power wire directly from the battery, and ground back there too. The ign. wire just turns it on so keep that one comning from the harness.

Jims79

Yes I used the original wire's. I try going to the battery I used a new ground already. I'll let you know it that is the fix.
Thanks
Jim

68AIR

I am not sure about your year but 73 has an external capacitor on the distrbutor that minimizes radio static

bozzman3

What does the noise sound like?If its a whine that goes up and down in pitch relative to engine speed, thats caused by the alternator.If its more of a static popping noise that is from the Ignition.

spedaleden

I agree with bozzman3. Connect power at the factory radio harness and ground radio to a piece of metal as close to the radio as possible. Do not run a ground wire to the battery. That is were your noise is comming from or the alternator. If its a wine from the alternator add a suppressor and you'll be fine. Also add a suppressor to the hot all the time wire (memory)

Durango_Boy

I guess I should have been more clear about the ground location. I said "Back there..." and meant behind the console in teh metal framing over the transmission, and to not use the factory location for a ground. The harness is wired so much into the ignition system that he's getting interferance from two places. He can isolate this by getting 12V directly from the battery and eliminating the ignition ground loop by grounding to the car's chassis.

Jims79

The noise or static doesn't change when I rev the engine. So its from the ignition? The stereo has a hot lead to the positive battery & a on/off hot to the ignition. Should I chg the lead to the ign to another source of ign hot? I did create a new ground right below the stereo to the chassis.

lucky76

I have the same problem you have and I've tried everything talked about in this thread and others before. Grounds, cleaning grounds, antenna, filters on power, filter on alternator, and nothing fixes it. I even took the belt off my alternator and started the car. It's not the alternator! Good Luck.

Jims79

I have one of the radio suppressor's from ecklers which has a red & black wire off the top. Can't find the install sheet so which wire to where. Is the black a ground and the red hot ? How do I install & where?

MixxMaster

put me down for a ground loop. Get thee to Radio Shack, they have something for that.

Durango_Boy

No, it goes inline with the 12V power wire. The red is the hot side of the lead, and the black would go to the stereo.

Jims79

Thanks again DB I'll try that fix today. Still like the old avaita girl.

bozzman3

It sounds like your noise is coming from the Ignition.The noise can come in in a few ways the power supply or ground wires,so try switching sources.The noise can also come in from your antenna wire reroute the antenna wire also ground the antenna body.Noise can also come through the speakers and wires.With the tuner of the radio off can you here the noise?That would tell you its coming in from the speaker side.Good Luck,most attempts on radio noise are only corrected by finding what actually emits them and replacing or repairing such said components.In line filters help a small amount but are not the cure all

bozzman3

In-line filters,go in between the radio and power source,the ground wire actually goes to ground of the car and not the radio ground

NHvette

I am an electrical engineer with several degrees in the subject
and many years experience.

First, if the noise is only occuring with radio reception and NOT with CD
playing, then it is pretty safe to rule out any issues with the power
and ground supply. The same power is used to play CDs.

So, that leads us to believe there are issues with the antenna or the
receiver circuitry in the radio itself. I would first check the condition
of the antenna connector at the radio side. Try to clean connectors.
If noise still persists, look to the rear: check under the rear quarter
and look to see the condition of the antenna ground plate and the
strap that connects it to ground. I think this is the most likely culprit.
You could try running a wire from the antenna base to a clean spot on the frame to test.
Also, the aluminum ground plate tends to corrode, and it may not be
contacting the antenna base properly.

To sum it all up, I think the antenna ... not power issues.

You could be picking up ignition discharge through the antenna, but you state
that it does not change with engine speed - so I ruled that out.
This is usually an issue with high performance coils and solid core plug wires.
A standard suppressor core plug wire takes care of most RF noise from ignition.

Durango_Boy

First. this problem is on his son's truck, not a Vette. I missed that too until a few posts ago I re-read everything. I too had originally thought antenna but he said he swapped it and changed grounds. That to me would rule out the antenna. I can't speak for the level of change, if only the mast was changed or if the assembly and cable were changed too.

The head unit may have some fault here too, in that it has a bad reciever circuit. It happens, and no matter how good the signal it sounds like you're in a tunnel.

If alternate power and ground sources don't change anything, try swapping in a spare head unit and see if it acts the same. If so you know it's either the antenna or electrical system causing the problem.

Jims79

[QUOTE=Durango_boy]First. this problem is on his son's truck, not a Vette. I missed that too until a few posts ago I re-read everything. I too had originally thought antenna but he said he swapped it and changed grounds. That to me would rule out the antenna. I can't speak for the level of change, if only the mast was changed or if the assembly and cable were changed too.

Yes I did write the problem was in a truck, infact its a nissan pathfinder so if you don't want to help that's ok. I tried everything suggested above. I chg'ed the hot lead, the ground, the antenna both mast and base, the ign lead, and last the radio itself. I have good plugs and plug wires on the car. Still noise on the am/fm not the CD. The noise does not get higher when I rev the engine but does go faster w/high rpms.
I guess I'm just going to listen to CD's and not the radio.
Thanks for all your help.
Jim

Durango_Boy

A thought. Some radio stations pump up bass to effect the peple's radios that don't have a good low range. A car with bad or dying speakers may not have a hard time with a CD because the sound channels are evenly weighed...whereas the radio stations extra bass it making the speaker's voice coils work harder than they can.