constant buzz from within dash and subwoofer
constant buzz from within dash and subwoofer This just started within the last few days. First thing that happened was the sub would pop and hum (although it may have been the sail panel woofers, not sure). Now with key off, engine off, door open, the sub will rumble and there is a buzz in the dash. I don't think the buzz is coming from the dash speaker because once I put my key in the ignition, it chimes like normal and the buzz still happens. This continues after closing the door again. I have to unplug the head unit to get it to stop. The buzz/rumble also stops if I turn the key backwards, turn the key on, or turn on the car. So it only happens when the sound system is supposed to click off after turning off the car and opening the door. If I unplug everything from the head unit it still happens. Any ideas??
Looks like the R.A.P. module or retained accessory power module could be involved somehow. Gotta figure out where that buzz is coming from...
Last edited by AdsoYo; May 26, 2015 at 05:01 AM.
So the buzz was definitely coming from the rap module. When I pulled it out, it was piping hot. The most recent thing I did was add a bluetooth adapter to the switched 12v wire for the head unit about 2 weeks ago. That means the head unit, bluetooth, and steering wheel radio control adapter were all 3 spliced into that switched 12v power. Is that too much? Can these modules be purchased anywhere or does it need to be remanufactured? Power windows and locks worked fine. I'd like to get this fixed before the weekend since I'm going on a long road trip. Would a V6 Firebird have this same module? I know the junk yards around here have V6 Firebirds and Camaros.
This is the little pocket where it was sitting
Here's the module itself
And with the cover off
This is the little pocket where it was sitting
Here's the module itself
And with the cover off
Last edited by AdsoYo; May 26, 2015 at 05:02 AM.
Joined: Nov 2003
Posts: 11,328
Likes: 345
From: Jacksonville, FL (originally from Toronto Canada)
Actually, by the part number that is the RAP module for a 93-95 Firebird and 93-96 Camaro. It has been superseded by part number 12135089. Retail price at dealer is $221 but it is available online for about 2/3 that price.
When I plugged the head unit back in after removing the module, the sound system made the same gentle pop it makes when I power it on normally. I interpreted that as meaning it would draw power with key off so I unplugged it again. You guys think I'm okay with head unit/bluetooth/IR steering wheel adapter all on the same 12v switched power?
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Joined: Nov 2003
Posts: 11,328
Likes: 345
From: Jacksonville, FL (originally from Toronto Canada)
Only you can answer that. The circuit is protected by a 15-amp fuse and the radio itself will use most of that. You'll have to determine how much current your other accessories might draw. They will usually have their own fuses so you might be able to just add up the amperage of their fuses to get a rough idea of their current draw. Anything more than about 5 amps is probably too much. But the best way is to actually measure the current draw with a meter. Remember, fuses are there to protect the wiring not the devices. The fuse must blow before the current flow reaches the point of causing the wire to heat up and possibly cause a fire.
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Verdad Gallardo Thanks for the explanation. Unfortunately it looks like rap module was fine after all. I just finished hooking up the new one and I'm still getting a buzz from the module and a rumble from the sub. Any ideas?
everythings fine with key on or car running, it's when the key is off and door opens that the buzz starts, when all power is supposed to be cut from the head unit
I had a similar problem in '90 Pontiac I owned once. I tapped in to the wrong power line for an accessory and the draw from that caused issues with other relays on the circuit.
Do you have any non-stock accessories installed in the car? What kind of head unit do you have? (I wonder if the head unit blew a capacitor, or something like that.)
Do you have any non-stock accessories installed in the car? What kind of head unit do you have? (I wonder if the head unit blew a capacitor, or something like that.)
I missed this. Does it happen with the key in or out of the ignition? How do you get it to stop? Does it taper off by itself or do you have to manually cut power?
It happens with the key in and out of the ignition as long as the door is opened OR 10 minutes have passed and the rap module cuts power. The noise does not taper off by itself. I found that out when the problem first started. I drove the car to work, didn't yet know the noise happened when power was supposed to be cut off and worked a 12 hour shift. Came back with the car buzzing and the battery drained to the point it was slow to turn over. The only way I can stop it is by unplugging the head unit. Windows and locks still work fine.
It sounds to me like the buzzing is coming from one of the relays. Maybe you can plug the module in, without the plastic cover on, and see which relay is making the buzzing. Maybe that would tell something? (I'm wondering of the signal from the BCM may be odd or not a steady/solid voltage.)
I was going to try hooking the bluetooth and steering controls up to the remote amp turn on wire coming out of the head unit and see if that does anything. Also my car does not have a BCM, those started popping up in 96.
I did what I should've done in the first place and tested the wires with a multimeter. Using radio ground and switched 12v I was getting whacky numbers so I used the door hinge instead of the ground wire and got 0.4v key off. Tested again with key on and got 12.6v. Traced the ground wire and saw it was barely making contact with the frame. Fixed the wire and things seem to be working ok.