Stereo Engine noise from BT/Assist module

[TechieCarGuy]

I've been troubleshooting some engine noise that I thought entered in to my car after I upgraded the audio system. However after a day of troubleshooting it seems that with all my audio equipment disconnected, the noise is coming from the BT/Assist module in the trunk. Then when my stereo equipment is connected that engine noise is getting amplified.

Basically, I have an e82 135 with Idrive and the base stereo. I upgraded my system to a 3way front stages, using the Hi-Level outputs from under the seat to feed an Audison Bit-One, which then sends the signal to a 6 Channel amplifier in the left corner of the trunk.

When I have my stereo system connected like this and mute the audio, I can hear a loud whining noise through the front speakers which changes pitch as you hit the accelerator.

When I disconnect power to the Audison and the 6 Channel Amp I can heard a very faint whining coming from the BT/Assist module in the rear. If I put my ear to it I can hear a whine that changes when someone hits the gas.

I spent half my day rerouting all my cables and wires to make sure I had no power wires running near the antenna cables going in to the BT/Assist module, to no avail.

Any ideas? Do I need a new BT/Assist module, or could I possibly see a benefit if I recoded my system to HIFi and terminated the speaker leads going into my Bit-One to RCA's and used them low-level?

[reisf]

Originally Posted by Quart

I've been troubleshooting some engine noise that I thought entered in to my car after I upgraded the audio system. However after a day of troubleshooting it seems that with all my audio equipment disconnected, the noise is coming from the BT/Assist module in the trunk. Then when my stereo equipment is connected that engine noise is getting amplified.

Basically, I have an e82 135 with Idrive and the base stereo. I upgraded my system to a 3way front stages, using the Hi-Level outputs from under the seat to feed an Audison Bit-One, which then sends the signal to a 6 Channel amplifier in the left corner of the trunk.

When I have my stereo system connected like this and mute the audio, I can hear a loud whining noise through the front speakers which changes pitch as you hit the accelerator.

When I disconnect power to the Audison and the 6 Channel Amp I can heard a very faint whining coming from the BT/Assist module in the rear. If I put my ear to it I can hear a whine that changes when someone hits the gas.

I spent half my day rerouting all my cables and wires to make sure I had no power wires running near the antenna cables going in to the BT/Assist module, to no avail.

Any ideas? Do I need a new BT/Assist module, or could I possibly see a benefit if I recoded my system to HIFi and terminated the speaker leads going into my Bit-One to RCA's and used them low-level?

The only possible thing i can think of that can explain this is that your alternator is working harder than it should which is why when you hit the accelerator the noise level increases - it directly corresponds to an increase in voltage. So follow up question, how old is your battery? Has it been recently replaced? Did it recently die? If it was recently replaced, was the battery change registered?

[TechieCarGuy]

Thanks for the reply. Yes the battery has been replaced within the last 6 months... I upgraded from a non AGM to an AGM battery. It was registered however and I have had no other issues. Is it possible my alternator is sketchy?

The alternator would make sense if I was running power hungry amps, but all are low power draw digital amps. I've added no other aftermarket stuff beyond the Audison Bitone, SR1d for sub (which isn't connected) and the Clarion 6 channel.

[TechieCarGuy]

Here's a thought... could I be picking up noise in the 12V power wire to my amp? I've run an 8 AWG fused power cable from the battery through the body in the rear of the trunk (behind the trunk latch). There was a perfect channel to snake the wire through, but I'm wondering if I might have created a ground loop or something.

As a side note, the amp is grounded at the factory ground point in the left fender well.. I've tried grounding there and directly to the battery with no avail.. the power wire, I have not tried to redo though so am wondering if that might be it.

[reisf]

Originally Posted by Quart

Thanks for the reply. Yes the battery has been replaced within the last 6 months... I upgraded from a non AGM to an AGM battery. It was registered however and I have had no other issues. Is it possible my alternator is sketchy?

The alternator would make sense if I was running power hungry amps, but all are low power draw digital amps. I've added no other aftermarket stuff beyond the Audison Bitone, SR1d for sub (which isn't connected) and the Clarion 6 channel.

When you go from non AGM to an AGM battery you need to have some special coding done other than just registering a new battery. I'm not 100% sure but im pretty sure it's the CAS module that needs to be reprogrammed