First thing to note: you cannot purchase a new steering angle sensor, the only parts available from volvo are steering angle sensors mated to clocksprings. A clockspring is merely a ribbon cable in a circular housing, the steering angle sensor is a delicate sensor. You CAN swap out steering angle sensors onto an existing clockspring, but the challenge is always sourcing the replacement.
Plenty of threads on removal so I won’t replicate it here.
Here are photos of the pair mated together, the end with cables coming out faces the steering wheel, the other side faces the firewall:
To separate the SAS from the clockspring, FIRST MAKE SURE THAT THE CLOCKSPRING IS LOCKED IN PLACE WITH A SCREW, AND TRY YOUR BEST NOT TO ROTATE THE sas UPON SEPARATION, then remove the three small screws shown here with yellow circles:
Here is the clockspring separated from the SAS (note–most ebay sellers incorrectly label the clockspring the SAS!):
If looking for a new SAS, make sure the part you are considering carries a Made in Japan label like this:
OK onto the SAS. The SAS consists of three primary components: a top-ring which faces the clockspring, a bottom ring which faces the firewall, and an inner ring which interfaces with digital sensors.
Step 1 to opening it up, is to move the three long screws which connect the three rings (from the top):
And the silver dots here are the screw ends on the bottom ring:
If you have succeeded in not rotating the SAS, you will see two tiny arows lined up on top of the unit:
Once removed, you can lift the top ring:
and the bottom ring will fall out.
Let’s now look at the inner ring that interfaces with the sensors, you will see three passthrough holes in green roughly 120 degrees apart , and two pin holes located exactly 180 degrees apart (this part is important!) in red:
Ok, trying your best not to rotate the inner ring, lets crack this open. There are 8 tabs to lift:
Which reveals the innards:
Remove the two screws holding down the circuit board, and:
Voila! A few things to note, the inner ring had tabs that are read by the sensors on the circuit board:
The inner ring also turns a gear that raises or lowers what I’ll call, the cumulative turn sensor (the tall vertical part that protrudes from the SAS case). Here are the gears, and also, a visual that shows when the cumulative turn sensor is zeroed out:
You want it zeroed out.
Here are the sensors beneath the circuit board, people have reported dirt in here that can obfuscate the sensors though I have never seen any myself: