2007 XC90

rssherwin1 · Post by **rssherwin1** » 11 Jan 2024, 04:49

Does anyone know where I can find the Volvo TNN (technical bulletin) that was released regarding the auxiliary port radio hissing sound coming from my speakers that speeds up with the increase in engine rpm? My car is currently at the stealership (not for this) and I asked about it while there and they informed me there is a TNN that has to do with repinning a wire on the radio harness. This is a job I can handle and would like to fix when I get the car back since they quoted the repin at $2100.

chitownV · Post by **chitownV** » 13 Jan 2024, 21:02

You could try a ground loop isolator for the car (3.5mm). I used one when I hardwired my cheap Amazon-bought Bluetooth module with a built-in microphone (the Bluetooth module may have come with the ground loop isolator). The alternator interference (whine) is a well-known issue when doing stereo systems or using an AUX. This is where twisted pair wire is used.

Here's an example of a BT kit that comes with the ground loop isolator. I used one of those windshield cling-on kits for stickers, cut the cling-on sticky plastic for the back of the BT module, and adhered my Bluetooth/mic to the center stack/dash. I can remove it at any time without residue.
https://a.co/d/6FL4coi

You can also ask the dealership to print out the TNN. If you do, please share.