On the two terms you asked about: KOEO just means “Key On, Engine Off” (ignition in position II, engine not running). LIN is the Local Interconnect Network which is a single-wire, low-speed serial line many Volvo “body” modules use to talk to the CEM (the SWM lives on one of those LIN branches). It idles near battery voltage and the data are short pulls to ground, so with a basic multimeter you don’t “see” square waves, you see a DC voltage that hovers just below battery because the meter is averaging the chatter.
How to do the quick LIN check with a DMM (no scope needed): leave everything plugged in, turn the key to position II (KOEO), put the black lead on a clean chassis ground, and back-probe the SWM’s LIN wire at the SWM connector (verify the exact pin/wire color in VIDA for your VIN so you don’t touch the yellow SRS circuits). A healthy, talking LIN will read ~10–12 V and may wiggle a few tenths as you work the stalks. If it sits rock-steady right at battery voltage, that points to an open LIN (broken wire/connector). If it sits near 0 V, that points to a short to ground. If power and ground at the SWM are good and the LIN looks alive at the connector, the SWM itself is almost certainly toast.
“Why would an SWM die just sitting?” Unfortunately, time and humidity still age electronics: electrolytic caps dry out, flux residues absorb moisture, and solder joints/copper tracks in the clockspring/SAS ring can crack even without miles. Battery tenders also aren’t perfectly ripple-free; they can spike on connect/disconnect. None of that proves the cause, but it’s very common to see column modules fail after long storage.
What to buy (2006 S60R, DSTC): the column is two pieces—(1) the SWM (switch housing) and (2) the clockspring/SAS ring. Typical P2 part numbers that fit your year/option set are:
• SWM (switch housing): 31318973 (supersedes 30798583; S60 2005-2009 with DSTC—double-check by VIN/chassis break)
• Clockspring/SAS (with DSTC): 31313083 (supersedes 31264469). This is the steering angle sensor + slip ring assembly.
You can source new from a dealer parts site (usparts.volvocars.com), FCP Euro/IPD, or go used from a same-generation P2 donor (match DSTC and stalk/button options). Examples: dealer listing for SWM 31318973 and FCP’s listing for clockspring/SAS 31313083. 31318973 – Steering Column Switch Housing. 5CYL. 6CYL. CH -327999. CH -650000. L.H.D – Genuine Volvo Part https://www.fcpeuro.com/products/volvo-air-bag-clockspring-xc70-s80-v70-s60-31313083
On P2 cars the SWM generally works plug-and-play, but you do need to calibrate the steering angle in VIDA after the job. Some shops/dealers will also insist on (or VIDA may prompt for) an SWM software reload during a “total upgrade.” In practice many folks replace SWM without a download; if VIDA later prompts during a full software session, they load it then. Bottom line: plan on SAS calibration now, and don’t be surprised if a dealer recommends an SWM reload later.
Install notes so it goes smoothly: disconnect the battery and wait ~10 minutes before unplugging anything in the column (SRS). Keep the wheel dead straight and don’t spin the new clockspring off-center (there’s usually a shipping lock/pin—leave it in until mounted). After reassembly, run VIDA’s DSTC/BCM “Steering angle sensor calibration” on level ground; confirm stalk inputs live in VIDA and that turn signals, washer, and wiper speeds return.
If your LIN check shows “open” or “grounded,” chase that wiring first. If LIN looks alive and you’ve got good 12 V and ground at the SWM connector, I’d replace the SWM (and the clockspring/SAS if you see any physical damage or if SAS faults pop up). That should bring your stalks, washer, and DIM buttons back to life.