Polo 6C RLS retrofit

Eduard: Please don't take offense, because none is intended, but a common problem with using multimeters is that folk tend to believe the reading on the meter! Very tricky things multimters - they are very good at doing what they are designed-for, but they are sh*t (again, no offense) at doing other stuff. Now, I'm by no means an expert on LIN signals, but here's a copy of a trace that I borrowed of a typical LIN signal from a SSP about this protocol:


So- first thing to notice is that the signal is a chopped-up square wave (well...... of a type) -Also notice the time scale on the horizontal axis which is 0.5 millisec per division. This means that your multimeter needs to have a frequency response of about 2,000 Hertz to measure a LIN signal. The other thing to notice about a LIN signal is the term "Recessive", which is just a fancy word meaning that this is the voltage of the LIN signal when there is no LIN activity. This means that the voltage on a LIN pin will be "High" (or near the battery voltage) when there is no communication activity (yes - it's kind of back-to-front logic, but it's because of the noisy environment)

So what does this all mean I hear you asking - well it means that a multimeter probably isn't the ideal instrument for your application. I assume that you had the multimeter scale set on DC voltage when you did your measurements. Without trying to explain what happens when a multimeter tries to read a signal that isn't DC when it's set on a DC scale, the reading that you have obtain (i.e.11.13 Volts) probably only tells you that there is little, or no "dominant" LIN signal. But this is just my very vague guess.

Sorry to be the harbinger of bad news, but you really do need an oscilloscope of some sort, or a device that can actually see a LIN frequency signal.

Don

DV25, thanks for the input, no offense taken, really, I was just hoping it wouldnt come to this, as it seems to me this gets to be a way bigger job than expected from a simple RLS. Looked up the PycoScope suggested by Martin, but God it’s expensive..

Will take another look at the cabling tomorrow. Question is, would it make sense to have almost batteru voltage coming from BCM LIN Bus ? As you can see in second picture, I’ve disconnected the sensor and checked LIN wire to GND, which seems to have voltage as well. Shouldn’t the RLS be the one sending voltage signals towards the BCM and not the other way around ?

Or, should I connect the multimeter to the LIN wire from the sensor LIN pin, and see what voltage does the sensor send, if any ?

Eduard: hmmm........ I don't believe so - sorry. LIN is a two way communication protocol. The module called the LIN master (the BCM in your case) requests a LIN slave control unit to transmit
information. The response is transmitted by the LIN slave (the RLS in your case).

Do you have an autoscan that was taken after you made the changes to byte 6? The auto scan in the first post has byte 0-1 set to zero

Don

Ok guys, I’m stupid. I’ve missjudged which conenctor is C and which is A from the BCM, not exactly realising the picture in the erWin is taken from the oposite direction.

So, I went on and removed the LIN bus pin from T73a/15 ( which is for Multifunction display call-up button ( reason why it was sending ~12V down the wire.

Now, I went to T73c/15 ( correct one lol), and there was already a wire in for the LIN bus (obviously) so I’ve spliced the cable and soldered the new one onto it, sealed it and thats it.

Went to VCDS, cleared all the DTCs, ran an autoscan, exactly the same errors, tried both sensors.

Used the multimeter again ( and checked the LIN wire with the multimeter, and the voltage is around 9.8v), a bit more than 80% ofthe battery voltage ( as mentioned by DV25 and the picoauto link posted by martin ) so I would guess thats a little bit better than what we had before ( lol ).

Question is, did I just break the sensors by initially running that wrong wire through them. Trying to figure out what could possibly be weong now that I know the wires are OK ..

@DV25, here's the post with all the scans, according to each change ( too bad they were on the wrong wire ), would do annother one, but they have the same fault codes, with the same coding. http://forums.ross-tech.com/showthread.php?11682-Polo-6C-RLS-retrofit&p=106568&viewfull=1#post106568

^ ^^^^^ Eduard - don't know if it helps, but you will find an autoscan of a Polo 6C with Rain sensor HERE from iichel. He (she?) has the same sensor as you (i.e. 5Q0 955 547 A)

And here is how the code-strings from the two BCM compares:



Don

PS: the tweak for a Golf mk7 for retrofitting a RLS is:
STG 09> Coding> ...
> Byte 6> bit 0-1 Set to 02
> Byte 7> Enable Bit 5

I'm a she, but that's ok

Looks like 5Q0 and 6C0 BCM behave the same way. On 6C0:

Byte 6, bit 0 and 1:
00 - No RLS
01 - RLS PR 8K3 + 8N4
02 - RLS PR 8K3/8K9 + 8N6

8K3 = auto light low beam + CH/LH + DRL
8K9 = CH/LH + DRL
8N4 = intermittent wiper with 4 settings
8N6 = intermittent wiper with RLS

you want 8K9 + 8N6

bit 0+1...
HEX 00 = BIN 00 = bit 0 off and bit 1 off
HEX 01 = BIN 01 = bit 0 on and bit 1 off
HEX 02 = BIN 10 = bit 0 off and bit 1 on

byte 7 bit 5 = auto light switch with ADL installed

You clearly know your stuff better than me, so, here goes:

8K9 - CH/LH + DRL :: I “kind of” installed these already, did all the adaptation settings, everything works ( aside LH and automatic CH, since RLS is malfunctioning )

As for 8N6, I guess this is done via the rain sensing function, after coding the RLS ? Or does it require something additional ?

Will just order the light switch and RLS based on the VIN iichel posted, knowing it came with it from factory.

I’ve ordered an OE light switch, 6C0 941 431 A WZU ( etka says its automatic / ch + lh for my car ), and they sent me a simple one, with no auto mode... so now I have to get another one.

Will just try with a new sensor, guess I broke these ones by plugging them into the wrong slot and will come back with the results, hopefully this fixes it.

If it still wont work, I’ll just wait for the dealership to update my BCM firmware.

EduardJS said:

You clearly know your stuff better than me, so, here goes:

8K9 - CH/LH + DRL :: I “kind of” installed these already, did all the adaptation settings, everything works ( aside LH and automatic CH, since RLS is malfunctioning )

As for 8N6, I guess this is done via the rain sensing function, after coding the RLS ? Or does it require something additional ?

Will just order the light switch and RLS based on the VIN iichel posted, knowing it came with it from factory.

I’ve ordered an OE light switch, 6C0 941 431 A WZU ( etka says its automatic / ch + lh for my car ), and they sent me a simple one, with no auto mode... so now I have to get another one.

Will just try with a new sensor, guess I broke these ones by plugging them into the wrong slot and will come back with the results, hopefully this fixes it.

If it still wont work, I’ll just wait for the dealership to update my BCM firmware.

Click to expand...

hi @EduardJs,
What is the result of this work?
rls retrofit, is it working?
I'm having the same problems.