05 STS broken suspension ride height sensor

[bill25]

I don't think they wanted to try to guess at mechanical problems.

I don't think it is crazy to verify that the 4 sensors are actually providing valid ranges, vice whatever is being sent by the sensor for "severed in half" (probably zero volts).

Code: Select all

for sensor in sensors{
  try {
    sensorVal = getSensorValue(sensor);

    if sensorVal <= 0{
        print("your sensor is probably decapitated")
        setTrouble("trouble_code_something")
     }

  } catch(err) {
    print(err.message);
  }
}

[kevm14]

My sensor is probably outputting a valid voltage though. Electrically it is working fine. I could verify this when I get home. If I unplug a sensor I guarantee the ESCM will throw a code.

[kevm14]

Made the trip home no problem. No warnings or speed limiters.

I got the new part. If I am really ambitious I'll install tonight because it should be pretty easy. Don't even have to pull the wheel - just jack up the front right.

I will check the voltage before and after via Tech 2.

[kevm14]

As I predicted, the sensor value was not bogus. It was in range.

Here is what it read when the right front tire was jacked off the ground.

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2.20V is probably the reading it had last, before it broke. I am not sure how this sensor works internally. I would not assume it is just a pot with a wiper.

Here is the new sensor.

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Installation was quite easy as I thought it would be.
- Jack up front right
- Disconnect harness plug
- Remove nut
- Remove sensor
- Install new sensor and thread nut on
- Plug in harness
- Snap upper rod joint on upper control arm

You can do this without even taking the wheel off.

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New sensor reading with the car on the ground. I did look at the value before I let the car down and it was like 0.98V. Forgot to snap a picture.

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Took it for a drive while graphing data from the sensors. It is reading perfectly.

And if I am not mistaken, the suspension seems....it's hard to explain. It seems like it is all working together. I don't think most people would have noticed the difference in ride and handling with a frozen sensor value. But it definitely seems to function better with them all reading according to wheel travel.

I took the car on a long test drive and bounced between Touring and Performance. This car handles well, I will say. I like luxury cars (and big cars) like this that are also fun to drive. That's pretty much what Cadillac has been doing since the Sigma CTS. Sales and consumer reception haven't always been there but it sure as hell works for my needs.

[kevm14]

On the drive in I can confirm that the suspension works better. Over the past week or two since I heard the clunking noise (sensor dangling) I noticed that it wasn't damping as well. Like if I went over a gentle bump on the highway, it didn't quickly settle the rebound. Well, it does now. Yay.

[kevm14]

On the drive in I can confirm that the suspension works better. Over the past week or two since I heard the clunking noise (sensor dangling) I noticed that it wasn't damping as well. Like if I went over a gentle bump on the highway, it didn't quickly settle the rebound. Well, it does now. Yay.

Amazing. Same exact symptoms, same exact problem except the right rear instead of right front. Well, I don't know if it is broken in half but it is the same otherwise.

As expected, I had another C0630 which is "Right rear position sensor circuit expected number of transitions/events not reached." Yeah, that's because it doesn't change AT ALL.

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Next test was to drive to the end of the driveway, onto the street and back in again, which cycles the suspension. Can only plot 3 things so I plotted the right rear, left front and right front sensors. The right rear is the thin line on the bottom.

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As I said, the others are registering suspension motion, especially the bump at the end of the driveway. The right rear is doing NOTHING. Well there was a tiny dip when the others made large swings. Clearly busted. Let's plot again this time with the left rear, right rear and right front sensors, doing the same thing:

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This time the right rear is the dotted line on top. It did NOTHING.

So that settles that. Tech 2 confirmed my theory about what was happening, so now I'll order a sensor. I can't wait to feel the difference. Also I wonder if this one will come apart in two pieces like the front one did. We'll see.

[kevm14]

One thing I may also do for fun is drive around and look at the damping percentages at each shock. I am surprised I've never done this. I want to see how the damping reacts as I drive the car, difference between Touring and Performance and stuff like that. This will be cool.

Oh, I ordered the Delphi sensor.

[kevm14]

Decided to get this done this afternoon.

Jacked up the right rear. Pulled the wheel. Well look at that. Broken in two just like the front sensor was.

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This was more difficult to reach than the front so it took more like an hour including jacking the car. Still not terrible but a little more reaching around stuff. New one installed.

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The result is that I could immediately tell just from the ride that it is fixed. Not surprisingly to me, it was not a shock issue. Here is the proof that it now works. RR.

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I said I wanted to graph the shock actuator current and drive around, so I did.

This is driving in Touring.

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And this is Performance.

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It looks like performance does NOT actually have a firmer baseline damping. It does however react more aggressively to body motion (with higher damping spikes) and as a result still does ride more firmly. Under about 10 mph, the system seems to disable itself and the shocks go to full soft. You can feel that but it was interesting to measure the behavior.

I do still prefer Touring for general driving around. But I do also feel like Performance handles better. Overall I am still fascinated by this suspension system. It is pretty cool technology.

Side note, there was a small pile of rust after I finished working.

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It also seems like Adam's weld for the air compressor mount has failed and one side of the compressor is now laying on top of the right muffler. Ugh. Well I have a welder now...but that's for another thread.

[bill25]

Side note, there was a small pile of rust after I finished working.

So you installed the weight reduction package too!

[kevm14]

If I continue long term ownership of this car I think rust is going to be the nail in the coffin, not anything else. I need to work a little harder on getting a cleaner example for the next one. Or just get a southern STS-V or something.