The DEFINITIVE V70 & V70R Subwoofer Installation Thread

Title is a bit silly, but I hope to write a pretty detailed/informative post on the subject which includes how to use and convert the '05+ harness to '04- cars, and vice-versa.

COMPATIBILITY: this post focuses mostly on '05+ cars for wiring, install method and parts are the same for both. For '01-04 wiring, see excellent info from @ScottishBrick and @LukeFlynn starting at post# 68 here

For aftermarket sub installs, @NuovoRecord and @vXoCl7v0o have cracked the code to keep the proper factory harness. See post# 37.
Alternately, to avoid wiring a relay circuit for aftermarket installs, @khnitz discovered that tapping fuse #22 in the REM (for an '05+ car) will grant ignition switched power.

PARTS & PRE-REQUISITES: pricing is current (ish) as of 2021

• Subwoofer assembly: 8648371 or 8633653 - still available from various sites around $500 or so, comes with subwoofer enclosure, amplifier, thumbscrew and bracket.
• Spare tire anchor, low profile: 9492798 - usually $10-13 - necessary so the subwoofer can sit above spare successfully. If you have a full-size spare, you'll need to get the donut.
• Carpet if you're crazy like me - 9468705 - available for around $90 or so
• Use my part search script to save some dough if you're buying stuff!

If you've acquired a sub secondhand without a bracket or thumbscrew, like me, you'll need:

• this knob, or one with same thread pitch/length/dimensions.
  Spoiler: Knob Dimensions:

  Star Grip Knob, External Thread, Screw Length 0.78 In, Overall Length 1.57, Thread Size M8 In, Dia 1.26 In, Knob Type Star Grip, L Style, Thermoplastic, Matte Black
• ...and to either fabricate a bracket, or contact @[email protected] here on Swedespeed, his brother makes phenomenal brackets for an incredibly reasonable price. I've installed two, and they're perfect. That's the bracket we'll be using in this post.

If you aren't pre-wired for the subwoofer, you'll need a harness - I've included the wiring diagram with pinouts and instructions if you want to craft your own harness, but the OEM one is still available from Volvo, and is relatively easy to install with the attached instructions. It also includes all the connectors you need, which would be a little bit of a nightmare to source and/or cut/solder, especially the REM side of things. To check if you're pre-wired, look below the cargo floor, under the lip by the tailgate latch. If you see a connector that looks like this, you're pre-wired.



If not pre-wired, you'll need:
- harness - 9499482 is for 2001-2004 wagons, and is available for ~$90 as of mid 2021.
NOTE: 30730120 is for 2005-2007 wagons, and is NLA as far as I can tell. Except for two power pins, they're identical, and that's easy to fix by removing the large combo power pin and soldering on two smaller pins from an '05+ REM connector if you have a 2005-2007 car. That process is detailed below.

INSTALLATION: Great, you got all the stuff! Let's begin. Follow the attached instructions exactly, read carefully - you don't need to take all the rear tailgate plastics/tailgate lip trim out like I did when installing the harness, but it did make running the cable below a little easier. I'll mostly be covering the parts that aren't covered in the installation manual, like retrofitting the '01-'04 cable for an '05-'07 car, and just lightly touching on everything else. Use the installation PDF mostly.

1. While your cargo floor is out, give 'er a good vacuum and wipedown if stuff spilled over the years.


2. You do need to take the left side panel off, but not the tailgate lip trim. Again, I did, but not strictly necessary.


3. For utilizing an '01-'04 harness in an '01-'04 car, just follow the install instructions, but the single big power pin goes in a different place in the REM than in a later car, get with someone who has VIDA to get the location for that pin, everything else is the same.

4. For using an '01-04 harness in an '05-'07 car, follow these steps.
- I harvested a brown REM connector from a wrecked 2005 car (S60, V70, whatever works - same REM) and harvested two of the pins from spots 1 and 2 - you can check if they're the right size by test-fitting them in the correct spots on the REM connector (pins 17 and 18 as indicated in the installation manual)


- This is the big combo power pin from the '01-'04 harness, we'll be removing this and putting a smaller pin on each of the two wires going into it.


- Here's the two pins I harvested, next to the big combo power pin.


- I then snipped off the big combo power pin, stripped the wires a little bit, and carefully pried apart each individual small pin's fingers to release the wire and make it possible to insert another wire. I then inserted one of the larger diameter wires, crimped it with the fingers of the smaller pin, and soldered it in, taking care to keep the solder low and package size small as to not interfere with the locking mechanism of the pin so it will still snap into the REM connector.