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WTF is up with the new stereo??? Static at idle

AddictedOffroad

AddictedOffroad

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Having fits with my new stereo in the Blazer. Okay, so here is the deal.

With the key in the ACC position the stereo acts normal. Sounds good, and doesn't have any issues. But, when I start the Blazer, it basically gets a good amount of static. Then when the rpms head up it levels out and works fine again.

Its driving me nuts. I have regrounded it, run new ACC and 12V wires, and its still the same.

The real kicker is that the old stereo never had this issue.

Any ideas?
 
How are your spark plug wires?

I've had vehicles with so-so condition wires that gave off a charge that interfered with the radio. Perhaps the new radio is that much more sensitive that it can pick up this interference.
 
AJMBLAZER said:
How are your spark plug wires?

I've had vehicles with so-so condition wires that gave off a charge that interfered with the radio. Perhaps the new radio is that much more sensitive that it can pick up this interference.
Click to expand...

Well, the static does kind of fluctuate with the idle rpms.

The motor only has 10K on it though. Brand new HEI distributor and plugs, wires, etc at the same time.
 
You know the last 2 sterios I have bought have had the same problem to fix it I had to run ground straight to batt neg. Dunno why but I tried everything too. Maybe newer sterios have some compatability problems with older electrical systems. New tech and super sensitive equipment maybe they just pick up more noise.:dunno::saweet::woot:
 
i remember my friend bought so plug wires for his car but he didnt know that they were "race only" so there was no "electrical suppression" or something and gave some nice static...only with the radio though,CD's worked fine.
 
original balzer said:
You know the last 2 sterios I have bought have had the same problem to fix it I had to run ground straight to batt neg. Dunno why but I tried everything too. Maybe newer sterios have some compatability problems with older electrical systems. New tech and super sensitive equipment maybe they just pick up more noise.:dunno::saweet::woot:
Click to expand...

I am going to try this in the AM.
 
original balzer said:
You know the last 2 sterios I have bought have had the same problem to fix it I had to run ground straight to batt neg. Dunno why but I tried everything too. Maybe newer sterios have some compatability problems with older electrical systems. New tech and super sensitive equipment maybe they just pick up more noise.:dunno::saweet::woot:
Click to expand...

<Sigh>

Just decided to go out and run a test lead to the battery Neg. No difference.

But, I can confirm that the ground wire doesn't need to touch anything and the stereo still works and has the same problem. Could it be grounded through the dash itself? Its a metal dash on a 72' Blazer.
 
AddictedOffroad said:
<Sigh>

Just decided to go out and run a test lead to the battery Neg. No difference.

But, I can confirm that the ground wire doesn't need to touch anything and the stereo still works and has the same problem. Could it be grounded through the dash itself? Its a metal dash on a 72' Blazer.
Click to expand...

Also just tried going directly to battery with constant 12V Battery and ground. Still no change. I'm at a loss at this point.
 
You may need a capacitator to absorb some of the electrical noise coming from your engine. Some of the older trucks have them installed from the factory.

If you go to any stereo shop and explain the problem you are having, they'll have what you need to eliminate the noise.
 
Yes, the radio can ground through the dash, but only if it physically attaches. It also grounds via the antenna cable, which has the shield tied to chassis near the antenna. If you have a mast antenna, a great troubleshooting aid is to unscrew the mast. If the noise goes away, it is a radiated problem and no amount of grounding changes will help. You have to fix the ignition system. If the noise is the same without a mast, you have a conducted noise problem with noise on the power lines (filter) or a ground loop (remove one of the grounds.Have you tried drawing power from a different place?
 
Blue85 said:
Yes, the radio can ground through the dash, but only if it physically attaches. It also grounds via the antenna cable, which has the shield tied to chassis near the antenna. If you have a mast antenna, a great troubleshooting aid is to unscrew the mast. If the noise goes away, it is a radiated problem and no amount of grounding changes will help. You have to fix the ignition system. If the noise is the same without a mast, you have a conducted noise problem with noise on the power lines (filter) or a ground loop (remove one of the grounds.Have you tried drawing power from a different place?
Click to expand...

Yes, I have drawn power from several places on both the constant 12V and the ACC lines including directly to the battery. No change.

Not sure I have a mast antenna. What exactly is a mast antenna? Looks like a stock one that just folds into itself.
 
One more thing to try is to disconect your ALT. and try it again. Im not sure what it is in an ALT. that can cause the radio noise but I do know they can.

IIRC its the diodes that act as one way valves for electrical current, hell I cant remember. I do know my 79 lincon had terible radio noise then the ALT went bad. New ALT and the radio noise went away.
 
If you've checked all your grounds (sounds like you have) and know the radio is good I would bet that it's your alternator. Do you have a CB or anything else aftermarket (heaters, extra cigarette lighters, etc.) in the electrical system?
 
By mast, I mean a monopole - a rod of some kind sticking out of a fender. If you can take it off without unplugging the antenna cable (disconnecting the coax shield confounds the results), it gives you a radiated/conducted determination.

Noise almost has to be from the ignition system or the alternator. Make sure you have the ground strap from the distributor to the engine block. If aftermarket ignition, make sure it it grounded back to the block.

If the alternator has bad brush noise, you can just disconnect it and run for a while. If the noise stays, it is from the ignition. I got bad radio noise from a failing coil before.

Another good troubleshooting method is to keep the radio mounted where it is, but power it from a separate battery.
 
Well, I am happy to report that I am officially a dumbass. :rolleyes:

The only ground I never checked was the neg cable on the battery. Well, it was slightly loose. I moved it, and viola no more issue. :doah:I feel like a complete douche right now. I even wired in a filter for the stereo this morning before hand too. So, I pulled it out and will take it back along with the rest of the new wires I bought.

I did run another ground from the battery to the frame for good measure, but at least I have tunes at idle now. :rolleyes:
 
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