FIXED: S60 DSTC, SAS index 180 degrees

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I'm pretty excited to share this one.

The 09 S60 has one less warning light now. I've had it about year after giving the 05 to my daughter. The 09 was inexpensive due to high mileage, and moreso lack of final maintenance. The PO seemed to have paid for the major volvo sins (breather apparatus), TBelt and good regular maintenance but then just let it go. Torn upholstery, several idiot lights, vacuum leak(s), interior rattles, brake problems, worn unbalanced tires, wipers, and the like, so it's been rolling project. All the interior was fixable with no cost, including re-sewing the leather slowly by hand. Engine, turbo and trans were all solid and happy with regular maintenance. Vacuum issues are ongoing.

So after working the bigger problems, the annoying DSTC and headlight issue came next. The headlights steer with the wheel and always point hard left unless disabled at every startup. I don't need DSTC but I've been on a quest to reduce dash lights. Originally this would be given to my son, and thought that may change, I want it better for him.

So - my code scanner started showing me something interesting. Yes to the Steering Angle Sensor fault, and a panic code from the ABS module. But here's the thing, the SAS consistently read 180 degrees off, regardless of wheel position, and it was not erratic. It was very consistent and the data changed smoothly without glitches when I'd rotate the steering wheel.

I did the typical google search and it's usually a "replace it" part, with some sources saying they had to be calibrated. The vehicle also does a fact-check calibration itself, but I can't seeing calibration swinging wide enough to handle 180 degree variations. More google searching showed that this $300 part was keyed, so there's no way to install it 180 degrees off. 360 or 720 degrees, yes, 180, no.

So - I thought lets just tear into it and see if it could forced 180 degrees off, or accidentally assembled 180 degrees off. Steering wheel came off very easily to my surprise (first time). Two spring clips pop the airbag, one 22mm bolt releases the wheel, and it slides off without a puller. 3 screws and the clockspring/SAS unit are in your hand. I did all of this very, very carefully in 15 minutes. Repeating, it'd take 5.

The SAS and clockspring are a single unit, but three small screws later and they separate. The clockspring has two prongs with grab the steering wheel, plus a large plastic cable guard, which all match the steering wheel. The SAS is mounted to the back of the clock spring and has two nubbies, a large and a small, 180 degrees apart, which mate with matching holes on the back of the clockspring. This made it very easy. I took a drill bit and drilled out the smaller opening in the clockspring to accept the larger nubby from the SAS, (without going too far into the spring), spun the SAS 180d to the right and put it all back together.

It worked. The car needed a drive to attempt it's calibration/fact-checking and now it works and the headlights behave too. No fancy tool was required to perform additional calibration.

Somehow I disturbed the turn signal cancel pawls, if that's what they are called in volvos, as now for both L & R they won't cancel for shallow turns (90d wheel) but only sharper turns, but that's not a big deal and I can go back in there later. Just tickled to have fixed this at no cost.

Perhaps this will be helpful if other people run into this problem of a SAS reporting consistent numbers deviating from truth. It does beg to question how it started, if the PO attempted a repair and maybe installed an incorrect part, or what, hard to say. But in this case with a careful hand the SAS was re-indexed.

-m
 
I refuse to drive a vehicle that needs to know the angle of the steering wheel.

What idiot engineers features like this into a car?!?
 
Lots of cars need steer angle; most vehicle stability programs use steering angle as an input to the computer to determine whether the car is skidding.
 
Not to mention performance paramaters like AWD or SH-AWD.

I'm not a fan of extra nit-n-noids, but it's a fun car and I can't hold this against it. It's a great engine and chassis!

-m
 
cheers3.gif

Nice work on that one.
 
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