Rain/light sensor & humidity sensor

[Wafflehd]

Hello,

Any fixes for codes:

01520 - Rain/Light recognition sensor

01229 - Humidity sensor

I have already replaced the gel pack and that did not work.

[Smac770]

If you have DTCs, then the problems are electrical or operational. The gel pack would seem uninvolved.

You post a couple DFCC numbers, but no actual problem codes / descriptions. So we know what the car is saying is having a problem, but no idea what the actual problem is.

[Wafflehd]

My auto high beams, and my auto wipers are not working.

unrelated but my lane assist and ACC isn't working.

[Smac770]

US B8 didn't have high beam assist. You mean auto driving lights (the headlamps come on automatically when it gets dark out)? So at least one aspect of the RLS is working. But again, you've not posted the actual error text for the device, so there's no way to speculate about what is wrong. Where did you get the DFCCs from? If VCDS, then post the complete scan log text. And is this a B8.0 or B8.5?

[Wafflehd]

B8.5, I’m using Obdeleven.

[Smac770]

https://www.audizine.com/forum/showt...ning-interface

So we see similar there, where the OP posted a DFCC (component code) and the text for that DFCC, ie the name of the component. But didn't post the actual error. Later, he then posted the actual error, no signal/communication. OBDeleven might post the DFCC as a fault code, but it's not a fault code; the DFCC alone says nothing about the actual fault, it only identifies the component involved.

https://youtu.be/XGuxYSeD8a8?t=23
The red text is the component involved, the white text is the actual error condition.

Apparently you can get the log of all this out of OBDeleven, from another's post: "If click garage, your car, history, you can see everything since you started using the app. You can then click the upside down triangle hamburger icon and email the logs to yourself"

[Wafflehd]

https://www.audizine.com/forum/showt...ning-interface

So we see similar there, where the OP posted a DFCC (component code) and the text for that DFCC, ie the name of the component. But didn't post the actual error. Later, he then posted the actual error, no signal/communication. OBDeleven might post the DFCC as a fault code, but it's not a fault code; the DFCC alone says nothing about the actual fault, it only identifies the component involved.

https://youtu.be/XGuxYSeD8a8?t=23
The red text is the component involved, the white text is the actual error condition.

Apparently you can get the log of all this out of OBDeleven, from another's post: "If click garage, your car, history, you can see everything since you started using the app. You can then click the upside down triangle hamburger icon and email the logs to yourself"

Thanks for that, I’ll copy and paste below.

09 Central Electrics
System description: BCM1 1.0
Software number: 8K0907063DJ
Software version: 0103
Hardware number: 8K0907063DJ
Hardware version: H16

Faults:
01520 - Rain/light recognition sensor
static


01229 - Humidity sensor, A/C system
static

When I look on OBD11 they both say "No signal/communication"

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[Smac770]

On a B8.5, the G355 humidity sensor and the G397 RLS (rain light sensor) are combined into a single unit in the rearview mirror housing. This unit has a 3-pin plug, 12v on 1, ground on 2, LIN bus on 3. No comms could mean a lack of power, so you'd want to check the fuse (fuse 12 in column brown on the driver's end of the dash). If the 12v is fine, you might want to check at the 3-pin plug itself. If the 12v to ground (pin 1 to pin 2 on the harness plug) is good, it might be a problem with the LIN wire, or a problem with the unit itself. The unit's LIN connection is to the same LIN wire as the J400 wiper motor. So if the wipers work at all, the LIN wire from the J519 is at least partially intact.

You can see the RLS and the three-pin plug here: https://www.audizine.com/forum/showt...d-Light-Sensor

It would be not possible for the headlamps auto on/off to function if the J519 is unable to communicate with the RLS.

There are measuring blocks (live data as OBDeleven terms it) for the J519 that show the reported values from the RLS. I've tested this myself, using a flashlight to see at what values the headlamps turn on/off, etc. But I have a B8.0, don't know if the blocks are the same in a B8.5 J519 (J519 = BCM1). The J519 was changed quite a bit for the facelift.

[Wafflehd]

On a B8.5, the G355 humidity sensor and the G397 RLS (rain light sensor) are combined into a single unit in the rearview mirror housing. This unit has a 3-pin plug, 12v on 1, ground on 2, LIN bus on 3. No comms could mean a lack of power, so you'd want to check the fuse (fuse 12 in column brown on the driver's end of the dash). If the 12v is fine, you might want to check at the 3-pin plug itself. If the 12v to ground (pin 1 to pin 2 on the harness plug) is good, it might be a problem with the LIN wire, or a problem with the unit itself. The unit's LIN connection is to the same LIN wire as the J400 wiper motor. So if the wipers work at all, the LIN wire from the J519 is at least partially intact.

You can see the RLS and the three-pin plug here: https://www.audizine.com/forum/showt...d-Light-Sensor

It would be not possible for the headlamps auto on/off to function if the J519 is unable to communicate with the RLS.

There are measuring blocks (live data as OBDeleven terms it) for the J519 that show the reported values from the RLS. I've tested this myself, using a flashlight to see at what values the headlamps turn on/off, etc. But I have a B8.0, don't know if the blocks are the same in a B8.5 J519 (J519 = BCM1). The J519 was changed quite a bit for the facelift.

So the fuse is good, do i just use a voltmeter to check the pins?

[Smac770]

Sure. Test for 12v from 1 to 2. Also, check from 3 to 2 that you read some kind of voltage. LIN bus will bounce between 11v for logic low and 1v for logic high as communication occurs. The J400 windshield wiper is on the same LIN bus. If you don't see any voltage value (a meter is just going to give you some averaged value, so something between 11v and 1v), turn on the wipers and see if you see any voltage activity (as the J519 will have to tell the J400 via the LIN bus "hey, start wiping". If you can't get any voltage reading from 3 to 2, there might be a wiring issue, maybe where the LIN wire from the mirror splices into the wire from the J400 on the way to the J519. If you are seeing voltage value measuring from 3 to 2, it might be the RLS unit itself then. You'd normally measure the voltage on the RLS side pin 3 while you apply 12v and ground to 1 and 2 to see if you see the RLS signaling on the LIN pin.

Obviously, a scope with a LIN protocol analyzer would be the real way to go. But if you don't have a few grand laying around, ... :-D

[Wafflehd]

Alright so apparently I have no idea what I’m doing, I bought a voltmeter and now I’m unsure where to go from here.


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[Wafflehd]

image-2023-03-15-16:42:02-022.jpg
image-2023-03-15-16:41:48-284.jpg


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[Smac770]

You're on 200V AC range. The DC side has the bar with three dots under it. You want the 20V DC range.

[Wafflehd]

You're on 200V AC range. The DC side has the bar with three dots under it. You want the 20V DC range.

Got it, so red cable in one pin and then black in another pin on the other picture shown?


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[Smac770]

Not sure what you're asking. On the harness plug you have there, you should be able to make out a small 1 , 2 , 3 to know which side is pin 1 and which side is pin 3. Pin 2 will be the middle, that's ground. So put the black on pin 2, the red on pin 1, see if you read 12v. Then move the red to pin 3 and see if you read any voltage activity. You may have to do something like turn on the wipers to generate LIN bus activity to be sure there's something to see measuring pin 3 to pin 2. I believe the pin 1 to pin 2 should report 12v all the time, but it could be term 15 (ignition on), so have the electronics on and see if that gets a reading, if you get no reading with car off.

[Wafflehd]

Not sure what you're asking. On the harness plug you have there, you should be able to make out a small 1 , 2 , 3 to know which side is pin 1 and which side is pin 3. Pin 2 will be the middle, that's ground. So put the black on pin 2, the red on pin 1, see if you read 12v. Then move the red to pin 3 and see if you read any voltage activity. You may have to do something like turn on the wipers to generate LIN bus activity to be sure there's something to see measuring pin 3 to pin 2. I believe the pin 1 to pin 2 should report 12v all the time, but it could be term 15 (ignition on), so have the electronics on and see if that gets a reading, if you get no reading with car off.

Getting 13.6v with car on and off on pin one and then 10.2v on pin 3


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[Smac770]

So you're seeing voltage on both the power line and the comms line. I'd have to guess maybe the sensor is toast.

[Wafflehd]

So you're seeing voltage on both the power line and the comms line. I'd have to guess maybe the sensor is toast.

Now the question is do you go for the $35 used one and hope for the best or the $260 new one


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[Smac770]

I'd get a used one. What is the current unit on the car? Appears the repair part in the catalog is 81A 955 547 B, previously 8U0 955 559 C, previously 8U0 955 559 B. Looks like it would be 8U0...B on the car if the original is still on it.

Such as https://wolfautoparts.com/catalogsea...t/?q=8u0955559

A new one would include the gel foil, but you'll need to get a new one for a used unit. 8U0 955 609.

[Wafflehd]

So I replaced it with a replacement and it did not work. I still have the rain sensor issue


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[Smac770]

I'm unsure at that point. Two different sensors are not likely to both be flaky. Pin 1 to 2 shows power present, and pin 3 seems to show connection back to the J519. The windshield wipers are on that same LIN bus as the sensor pin 3. The windshield wipers operate fine? That 10 volt reading from pin 3 to pin 2. Does it fluctuate at all, or is it just always sitting on that same voltage. Comms line, it should bounce a little bit. Is this measurement with the sensor connected to the plug or disconnected?

Probably next thing to do would be to unplug the 16-pin plug from the J519 (under the dash, behind the headlamp switch) and check for continuity from the 16-pin plug pin 2 (violet/white wire) to the 3-pin plug pin 3 (also violet/white wire). Make sure it tests with a low resistance measurement, couple Ω at most.

Did the car come stock with the RLS, or is this some kind of retrofit experiment? Any reason to have to consider the coding or adaptations of the J519 control module for the issue?