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Discussion Starter · #1 ·
Broke a rod on the front sensor a few years ago, found out back the how expensive this sensor is. Managed to fix it so I wouldn't have to spend €150 on a new one.

Since last week my headlights point into the night sky, blinding traffic traveling in the opposite direction. Hookup up MES, found out that the front sensor is working just fine, but the rear sensor isn't doing anything anymore. Stuck at 1.77V, I guess the car thinks the boot is way up in the air compared to the front and correcting the lights for it. Step motor was at position 199. I guess that's as high as it goes.

Managed to do a calibration, which dropped it back to 161, which is still too high, but at least I'm not illumination the moon.

Anyhow, the rear is even more expensive, €200 for a new unit. I also can't find any secondhand/scrapyard sensors. Looking for a replacement I cannot help but notice that some german branded cars use these kind of sensors too. To the eye they look identical, but 10x cheaper. The connector looks the same, but it's so difficult finding good specs for the OEM part that's almost impossible to compare.

Anyone know if these things are interchangeable, can't imagine they customized this thing for Alfa Romeo (Giulietta uses the same component). I'm afraid of just ordering one to try it, not willing to take the risk of damaging a incompatible circuit board.

Hopefully the rear sensor isn't broken but rather one of the connecting rod is. I might be able to fix that just like the front, or at least manually adjust the current position so the beam is kinda where it should be. Coming weekend I will be able to take the rear wheel off and have a proper look (with daylight).
 

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Unfortunately can’t help you, but if it helps I can check for you which position the stepmotor is on mine when standing level (2WD wagon)
 

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Discussion Starter · #3 ·
Unfortunately can’t help you, but if it helps I can check for you which position the stepmotor is on mine when standing level (2WD wagon)
Yes that would be interesting. I've also logged my short trip around town. You can see the result of the speedbumps in there too. Note: the very last thing at the end of the graph, I parked the car and jumped on the tow bar a few times :). All the way through you can see that the rear sensor isn't registering any change.

Btw, I recorded this after I did the calibration, hence they start at step level 161.

Note: the file is a .txt extension, but it's a CSV. But that extension is not allowed to be attached to this post. So change it back before importing it in MES.
 

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Discussion Starter · #5 ·
Yesterday evening I decided to have a look, it's very annoying driving like this.

Found out that the rod came lose, that explains things. I managed to push it back in, was pretty hard to get it out again. Not sure how it became lose in the first place. See attached pics.

Anyhow, dropped the car down, light was perfect. Stepper motor showed 100, looked very nice to me. I figured to re calibrate again, biggest mistake of my life. Now they seem high again, not as high as they were before, but still too high for my liking and definitely blinding oncoming traffic occasionally. The stepper motor is at 161 again.

The only thing that significantly changed is the voltage (position) of the rear sensor. They (front and rear) show almost the same voltage (position). It's weird that after calibration the lights are too high, given that both sensors are hooked up and working again.

I'm going to fool the car tonight, jacking up the rear, re-calibrating and dropping it down again. That should do the trick is what I'm thinking now.

Attached is also a csv from AFTER the fix before the re-calibration. I forgot to log the one after the re-calibration.

@Leo_NL I'm very interested in the values your sensors were calibrated to. That would be the "Font sensor calibration voltage" field and the "Rear sensor calibration voltage" field.
 

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Aren't you supposed to complete a system calibration, and then manually adjust each headlight with adjustment screw on top of them, if they still are out of spec?
 

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Discussion Starter · #7 ·
Is a complete system calibration different from the headlight calibration? There is only one option to choose from in MES for calibration.
But the headlights have always been 'good'. Then it shouldn't be needed to physically adjust the headlights themselves with a screw or am I mistaken?
 

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I had very little time and haven't made a run yet, but quickly connected MES while standing level in the garage.
Values of mine seem little lower, but not too much different (I guess).

F & R, resp. 2.32 & 1.66 V
See attached PDF for all values as recorded from the L-side headlight.

But now you got me also pondering, I didn't see the light beam going from full down, from resting postition, to normal driving level. Something I probably got used to, but didn't pay attention to. Until today, focussing on your story. I hope to find some more time tomorrow and see if I can make a run for you (and myself now ;) ) Btw, the light beam projection by my car looks normal. It's just that I wonder if it's adjusted when loading the back/boot or when riding over a sleeping policeman.
 

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See attached 2 files made,

one while car jacked up with its rear end high-up in the air, with a dis-assembled sensor rod from anti-rol bar and manually activated while recording,

second file from a run starting on a B-road, followed by village lane with a number of speed bumps at constant speed, then a small stretch of cobble stones and finally parked-up while manually pushing the car down at the back with opened boot hatch.

(I didn't fit the towbar for that, so it tells perhaps more about my Popeye arms not being able to push the back down so much).
 

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Discussion Starter · #10 ·
Thanks, useful info! You went through great bit of trouble collecting this data.

Two things stand out to me.
First thing that I notice is from your first recording, when you disconnected the rod. The voltage range of the sensor when manually moving it is quite little(2.32 to 2.96). When mine was loose, it showed ~1.7V. However in your run (second recording) it drops down to 1.8v (must have been quite the speed bump haha).

Second is that the rear sensor (on your car too) is calibrated with it's ass up in the air. Given that it's calibrated value is 1.6V. Yesterday evening I jacked up the rear quite a bit. The rear sensor showed 1.8V and a re calibrated the system. While jacked up the step motor showed 161. Dropping it back down the stop motor went to 101, which resulted in a light beam I'm happy with.

Also noticed that the stop motor can go over 200 (225) when I got the rear in the air pre calibration.

Btw, I looked for a replacement rod, that small 10cm thing thing between the sensor arm and the anti-rol bar, it's 50 euro, crazy.
 

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You’re welcome!

Forgot to add that mine is sitting on a factory lowered suspension; maybe this clarifies the little difference in values(?)

Anyway, glad yours is driveable again without need of any replacement part.
(50 euro is ridiculous money indeed, I will now even more often grease those little rod-ends. They take a lot of punishment, considering where they are situated.)

You just also triggered me to double-check things as I realized I did no longer, and still don’t, see the beam calibrating by itself. Not as it used to do upon switching on the dimmed lights (or as I usually run with them constantly on, when putting the ignition on).
At least that’s what I think it always did, but as the beam adjusts on movements, either by manually pushing or by MES activated (low - middle - high), I start to doubt whether my memory let’s me down here.

Does yours upon every time when switching on lights, or can someone else perhaps confirm?
 

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Discussion Starter · #12 ·
I've got the TI version too.

The only time I can see it is when the light switch is set to 'ON' and I insert the key. It happens right away. Look somewhere else for two seconds and you've missed it. Also only really noticeable when it's dark outside. The wife's Giulietta has a more advanced and longer startup procedure, it also moves on the horizontal axis, but that's because it has adaptive lighting. It takes ~4 seconds in total whereas the 159 you can miss it when you blink with your eyes twice.
 

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Okay then my memory isn’t letting me down :)

I will have another, but closer look next time. While, as you described, the stalk switched ON and then putting the key into its slot.

Thanks!
 

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As you described, it works! I did notice only after the beam was projected on a larger distance than when usually parked against the garage wall.

If however switching on the lights afterwards, i.d. first putting ignition on, they don’t go fully up & down as in a self-test.

Weird but glad that not only my memory still works, but the system in the car still as supposed too 😅

Btw, forgot to mention previously when manually activating height sensors, without engine running, the car makes a rather strange noise. Not what you expect from what I presume are just servo’s.
 
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