Innards of a clockspring / steering wheel angle sensor pictures

[92saturnsl2]

I recently had to replace the steering wheel angle sensor on my '07 Pacifica to get rid of the ESP and traction control lights on the dash. The sensor is integrated into the clockspring on this model. First time I've ever replaced a clockspring, but it was a 30 minute repair once I became familiar with it, which pulling the replacement part from a junkyard car allowed me to do. The local dealers said the part was discontinued and they can't get it, Rockauto had it for $380. The $13 junkyard part worked fine, and if that fails in future, I know where to find more

Curiosity got the best of me, since all you can see from the outside is a black plastic cartridge, so I took apart the old one to see how it works. The clockspring is as I was expecting, and what's described on the internet-- flat ribbon cable wound in a loose circle. The SAS on the other hand is pretty elaborate and surprised me. It's an optical sensor. There is a laser diode or LED that shines into a clear plastic diffuser/lens that turns the light 90 degrees allowing it to pass through a slotted wheel that turns with the steering wheel. The light passes through the slotted wheel into an integrated circuit that has a opening in it-- presumably some kind of light sensor. The slotted wheel is notched in such a way that I believe they have error checking built into it.

No idea what caused the old one to fail, but on a scan tool, it read the maximum value (6000+ degrees) at all times regardless of steering wheel position. Probably an internal short in something on that circuit board, or a broken connection perhaps.

SAS:

Clockspring side:

 

[Racer4]

Thanks for sharing never seen one of them in detail.

 

[Wrenchturner44]

Thanks for sharing. This is prime example of what will kill all modern cars......electronics and their obsolescence. Older cars from the 60's and 70's were mostly mechanical with parts that would wear out that could be replaced. With modern cars it is a chore finding the electronic bits that suddenly give up the ghost and are out of production and no longer available.

 

[92saturnsl2]

Thanks for sharing. This is prime example of what will kill all modern cars......electronics and their obsolescence. Older cars from the 60's and 70's were mostly mechanical with parts that would wear out that could be replaced. With modern cars it is a chore finding the electronic bits that suddenly give up the ghost and are out of production and no longer available.

I agree. Doesn't bode well for the "green" agenda; if cars were built to last, we'd be building a lot less cars and using less resources. There's way too many variables though. Cars up north typically don't see 15+ years regardless of what is put in them. Then you have the car mfg lobby which pushes planned obsolescence and the fact that our economy is built on consumption, which trains people to buy new things to keep up with the Jones'.

One thing is for sure, there won't be many cars on the road from this era 30+ years from now, except the few models with decent aftermarket support. But that might be a moot point if you can't find gasoline to fill it up!

 

[SC Maintenance]

I really like my ECU controlled car. I turn the key and it runs. Of course my profession is electronics so they scare me less - but the obsolescence is the issue. Back when carburators were a thing you were always messing with them, and heaven forbid let one sit for a couple weeks and have it start.

I think the ideal rig would be something early - with throttle body and a ECU, but not too many other electronics. I Always figured I should do some research to see what era / vehicles fit that description - I think early 90's Fords with OBD1, likely same era GM products.

 

[jsean]

That’s some old tech there! Most tier 1s got away from that ribbon cable stuff to more robust angle/torque sensors like 10ish years ago - far more reliable and less finicky.

OP, are there any markings of who made that SAS?

 

[92saturnsl2]

That’s some old tech there! Most tier 1s got away from that ribbon cable stuff to more robust angle/torque sensors like 10ish years ago - far more reliable and less finicky.

OP, are there any markings of who made that SAS?

No manufacturer identifier that I can tell. Only thing that appears anywhere inside or outside is a sticker with date of manufacture (01/2005) and Mopar part no. 56046083AA.

This is a 15 year old car, so I wouldn't expect it to have torque sensing ability or anything beyond plain steering angle. But the SAS is digital, the ribbon cable is just to get data/electrical from the stationary column to the spinning steering wheel (airbag & buttons), which I assume all cars have.