Coming Home & Leaving Home Lights Enabled

Looking at the wiring diagram it looks like pin 12 on the connector E needs to go to the light switch rather than the earth.

homecoming.jpg
 
Yeah I'll check it out when I do the puddle light install, I've had the dash off before to do the footwell lighting and nearly broke one of the clips off... so I think I just have one shot left at getting it right. Unless someone manages to pull theirs apart before that ofcourse.
 
The 4 wires going to T6j connect directly, and only, to the coming home button on the light switch. T6j/1 goes to earth. I'm not dead sure where T6j/4 and T6j/2 come from but one supplies the switch with the power for the small light that is permanently on (similar to the light for the main light switch) the other, I would assume, comes from light sensor to tell the set up whether its day or night. T6j/3 goes to the pin 12 of connector E. With Marc's wiring, he's basically bypassed the switch and connected earth straight to E12, thus enabling a permanent, non-switched connection.

I've retro fitted a new light switch with the coming home button and made up the wiring the same as in the diagram. I've got Zenon's and with the coming and leaving home functions activated in Vagcom, the features work fine when the coming home button on the light switch is pressed on. I can't see the difference between having the button and not so in theory, the function should work. But there again, I haven't managed to get the auto lights working so I'm no expert!
 
RobinA3 said:
Looking at the wiring diagram it looks like pin 12 on the connector E needs to go to the light switch rather than the earth.
Click to expand...
Yes, as stated earlier in the thread if you have the light switch with the button for CH\LH lights then what i suspect happens is that the wire comes from pin 12 to the switch out the other side and then to the earth pin in the switch harness. Essentially what this does is give you the option to disable the CH\LH lights by turning them off at the switch.

This is obviously a nicer way to do it as you have the option to disable them, however it does require that you buy a new switch as well as the repair wire. I've achieved the same effect for the price of a single repair wire (which I actually got for free anyway), but don't have the ability to disable the CH\LH function with a button. If I really wanted the option to disable them I could always pick up a 99p toggle switch and mount it under the dash somewhere.
 
RobinA3 said:
Looking at the wiring diagram it looks like pin 12 on the connector E needs to go to the light switch rather than the earth.
Click to expand...
One other question Robin - In VAGCOM have you set the option for "Coming Home" by personalisation or LightSensor? The box needs to be unchecked (personalisation) for it to work with the notes I've documented.

Byte 02 Bit 4 Coming-Home via (1 = Light Sensor / 0 = Personalisation)

Older versions of VAGCOM may list this as (1 = Potentiometer / 0 = Adaptation)
 
Yeah the box is unchecked on the old vag-com..............i'll have to do some more investigation this weekend.
 
So mitch what you are saying is that it didn't work when you changed the coding and fitted the wiring and now you have removed the wiring it now works?
 
mitch78 said:
:think: I'm confused, but I've got it working.

I disconnected the wire that I installed earlier just to make sure it wasn't shorting something with my car having xenons, and I left the VagCom coding so that the options were selected. And in the words of The Great Soprendo, "Piff paff puff" it works!

I could have sworn that I'd tried changing the coding when I first got the car, and it made no difference, so I've no idea why it didn't work then but does now.
Click to expand...

Mitch,
what option do you a have set under "coming home via personalisation\lightsensor" (or adaptation\potentiometer on older versions of VAGCOM)?
 
RobinA3 said:
So mitch what you are saying is that it didn't work when you changed the coding and fitted the wiring and now you have removed the wiring it now works?
Click to expand...

Well that's what I did. bi-Xenon's as well, no wire just ticked the option in VAGCOM and it worked.
 
I may be off the mark with this, but there was a thread over on navplus recently and I was advised by a user over there, that you just need to ground the wire once, rather than leave it grounded.
Now the guy was french so something may have been lost in the translation, but this it what he seemed to mean, which would explain why it now works for you Mitch.

I have not been able to check as I do not get my new A3 until wednesday, but just thought I would share this with you guys.
 
I believe what it means is that when the car tries to activate the CH\LH function it opens whatever is on other the end of pin 12 and makes the earth connection to turn the lights on and then shuts the connection off. It then makes another earth connection to turn off the lights after the timeout period.

I can confirm this is the case because while I was doing the install I was tapping the earth wire off various nuts under the dash to try to find the best place to attach the wire and each time I touched an earth the lights would go on or off depending on what way they were previously. Once the time-out expired touching and earth did nothing.

Not sure why it is working for mitch now if he has nothing in pin 12. It can only be because the xenons are wired in a different way.

The S3 I have at the minute has adaptive xenons and the CH\LH button on the light switch so if I get a chance before I leave it back I may have a go at taking it apart and see if I can shed any light on the problem (if you'll pardon the pun!).
 
just tried it on mine and taking the earth off had noeffect whatsoever, also double checked on vag-com to ensure the settings were correct and they are.
 
I had a go with this yesterday, while I was switching on Footwell, Puddle/Warning lights in vagcom in readiness for the parcel from Robin ;). I haven't had any luck with it either.

As you say touching the earth for a brief period activated or deactivated them, then I wonder if the CH/LH light switch is just a push switch, ie that it only earths pin12 when its pressed. ie that the switch is normally open (NO), then when it pressed, it closes the switch. Then when its released it goes back to open position.

If someone has the proper switch already, it may be worth checking this with a multimeter. (resistance setting or cable test setting) One end either side of switch.
 
I will check this tomorrow, I am intrigued now!!
I would say that it is a latched switch though, as there is a light which is on when the lights are activated and off when they are not. This light could be software controlled though i suppose. Ill check tomorrow
 
chill14 said:
As you say touching the earth for a brief period activated or deactivated them, then I wonder if the CH/LH light switch is just a push switch, ie that it only earths pin12 when its pressed. ie that the switch is normally open (NO), then when it pressed, it closes the switch. Then when its released it goes back to open position.
Click to expand...

This is what happened to me when I was doing the install - touching an earth activated or deactivated them. The CH\LH light switch is just a push switch that when closed makes the earth connection between pin 12 and the earth. there is also a live attached to the other pin on the back of the switch so when you press the button and close the switch the earth turns on the light on the button to indicate that CH\LH is enabled.
 
Anyone planning to buy the new switch unit with Auto lights and the new shiny chrome edges?

Anyone got the part no and know the cables you'd need to install it properly (for the CH/LH I mean)?
 
I bought the TT headlight switch with CH/LH functions and auto lights and the chrome edges to go on my S3 8P a while ago. Part number 8J2941531E-5PR from Vag Parts for £41.55 + vat and postage. It's exactly the same as the A3 one but with the shiny bits. There are a few variations, you need to order the switch with or without DRL's, Zenon's (which are auto leveling), with or without auto lights and with or without the CH/LH function button. You'll also need to order the connector which goes into the back of the CH/LH button, as this isn't present if you don't have the function factory fitted, along with some repair pins.

I've managed to get the CH/LH lights function to work, which is also switchable (on or off) using the button on the headlight switch. The wiring for the CH/LH button has been listed earlier in this thread.

The Auto lights I've not quite managed to work out yet. I'm having problems with the light sensor I've fitted and not had much spare time lately to work it out. So far I've fitted a new windscreen, light/rain sensor and auto-dimming rear view mirror along with the Kufatec wiring harness. The auto wipers worked straight away after fitting the light/rain sensor but the auto lights are playing awkward. The problem is that the light sensor also plays a part in the CH/LH functions as even if the CH/LH function is turned on, if it's daylight, it stops the function working.

I'll get there eventually and hopefully be able to be more help.
 
boggym said:
So far I've fitted a new windscreen, light/rain sensor and auto-dimming rear view mirror along with the Kufatec wiring harness. The auto wipers worked straight away after fitting the light/rain sensor but the auto lights are playing awkward. The problem is that the light sensor also plays a part in the CH/LH functions as even if the CH/LH function is turned on, if it's daylight, it stops the function working.

I'll get there eventually and hopefully be able to be more help.
Click to expand...

Now that shows commitment! :hi: I have the light and rain sensors as a factory option. Let me know if you need me to look at my codings.
 
JohnS3 said:
Now that shows commitment! :hi: I have the light and rain sensors as a factory option. Let me know if you need me to look at my codings.
Click to expand...

Cheers John, will do. Just to clarify, do you have the light and rain sensors but without the CH/LH function, I thought it was all part of the same option? It's just handy to know because if you don't, then I know they're not linked. It just wipes out few of the several hundred theories I've got going on in my head at the moment. :uhm:
 
boggym said:
I've managed to get the CH/LH lights function to work, which is also switchable (on or off) using the button on the headlight switch. The wiring for the CH/LH button has been listed earlier in this thread.
Click to expand...

Cheers dude!

Have you got xenons?

So there are 2 pins on the back of the switch. One gets a live feed, the other pin connects to pin 12 and then earths it within the light switch itself.

Correct?
 
boggym said:
Cheers John, will do. Just to clarify, do you have the light and rain sensors but without the CH/LH function, I thought it was all part of the same option? It's just handy to know because if you don't, then I know they're not linked. It just wipes out few of the several hundred theories I've got going on in my head at the moment. :uhm:
Click to expand...

It's the light and rain sensors with the CH/LH function.
 
JohnS3 said:
It's the light and rain sensors with the CH/LH function.
Click to expand...

Cheers John, that clears that up.


Staz1000, yes, I have got Zenon's and DRLs'.

There are 4 wires going into the back of the CH/LH button on the light switch. One is for earth, another is for pin 12 (Black connector E), another is for pin 4 (Brown connector C) the other is for pin 10 (Black connector K). I know the main wires you need to connect are pin 12 (E) and earth as Marc discovered. One of the other wires is just for the illumination of the symbol next to the CH/LH button which is permanently on (when you are in the car) just like the illumination symbol for your light switch. (you can hardly see them in daylight). I don't know what the other wire does yet but I'm assuming it's something to do with the light sensor. There is another light which comes on in the middle of the CH/LH button when you turn the function on. It's separate from the general illumination light and much brighter. (you can see it in daylight). The other wire may be for this light but I doubt it.

At present, I've got the CH/LH function to work by fitting all the wires. I've got Zenon's so there may be a reason there somewhere as to why just connecting pin 12 to earth isn't working. The only problem I've got
is that although I can turn the CH/LH lights on or off, they work whether its light or dark. When fitted correctly, you should be able to leave them switched on all the time but they will only work if the light sensor tells them its dark outside. i.e. they won't come on during daylight.

Hope that helps
 
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boggym said:
The only problem I've got
is that although I can turn the CH/LH lights on or off, they work whether its light or dark. When fitted correctly, you should be able to leave them switched on all the time but they will only work if the light sensor tells them its dark outside. i.e. they won't come on during daylight.

Hope that helps
Click to expand...

Have you set the coding in VAGCOM to use "personalisation or light sensor" (adaptation or potentiometer in older versions of VAGCOM).

With personalisation it will always be on, with light sensor it will only work if for leaving home if the light switch is set to auto (and the button is pressed). The coming home is always active regardless of the position of the light switch. (That may be the reverse - LH always active and CH dependent on auto)
 
boggym said:
Staz1000, yes, I have got Zenon's and DRLs'.

There are 4 wires going into the back of ..........

........Hope that helps
Click to expand...

I see. It's a bit confusing with the way you have explained it but I'm not too concerned right now.

I'm trying to decide whether I should just do the simple wire mod as per Marc's instructions (hopefully someone will suss it out fully soon as I'm still waiting for a new laptop before I can try myself) or I can do a full Auto lights install using a light sensor I could make myself. I think the circuit would cost no more than £20 from maplins. But add the cost of the switch and then all the faffing about and I'm not sure if I'm really that bothered about it.
 
MarcQuinlivan said:
Have you set the coding in VAGCOM to use "personalisation or light sensor" (adaptation or potentiometer in older versions of VAGCOM).

With personalisation it will always be on, with light sensor it will only work if for leaving home if the light switch is set to auto (and the button is pressed). The coming home is always active regardless of the position of the light switch. (That may be the reverse - LH always active and CH dependent on auto)
Click to expand...

Yep, tried it with both ways. When I set the coding as "with light sensor" everything works as it should do for 1 attempt. i.e. I can switch the auto lights on in the daytime and they don't come on but when I turn them off and back on again, they come on! After the second attempt, the following errors are also logged-

Address 09: Cent. Elect. Labels: 8P0-907-279-23-H.lbl
Part No SW: 8P0 907 279 F HW: 8P0 907 279 F
Component: Bordnetz-SG H43 1201
Revision: 00H43000 Serial number: 00000007079325
Coding: F58E5F07A014100000000000000000000008EE175A0500
Shop #: WSC 06314 000 08192

Part No: 8P2 955 119 E
Component: Wischer AU350 H01 0130
Coding: 00062736
Shop #: WSC 06314

Part No: 4E0 910 557 B
Component: REGENLICHTSENSORH13 0100
Coding: 00141886
Shop #: WSC 06314

2 Faults Found:
02071 - Local Databus
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 2
Reset counter: 151
Mileage: 17124 km
Time Indication: 0
Date: 2008.07.14
Time: 19:57:00

Freeze Frame:
OFF
Voltage: 12.10 V
OFF
ON
OFF
OFF
OFF

01520 - Rain and Light Recognition Sensor (G397)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 2
Reset counter: 151
Mileage: 17124 km
Time Indication: 0
Date: 2008.07.14
Time: 19:57:00

Freeze Frame:
OFF
Voltage: 12.10 V
OFF
ON
OFF
OFF
OFF

The same happens with the CH/LH function. After clearing the DTC'S, it works as it should do for 1 attempt them stops working and produces the same DTC's.

I pretty sure its something to do with the wiring, so I need to check it thoroughly first, then it may be down to the light sensor (which I hope not as it's new from VAG parts).

If I use the "personalisation" setting, the Auto lights (in the auto setting)just come on regardless and the CH/LH function also works regardless whether it's day or night.

In addition, with the light/rain sensor installed and Vagcom set to "light sensor", the auto wipers work fine!!

Wow, if you understand that lot you should be Nuclear Scientist or something!!


Some answers that would be helpfull, if someone wouldn't mind, to help clear up some theories are:

1. What sensor does the auto lights and CH/LH use to determine whether it's daylight or not? There are 2 sensors on the rear view mirror and there is a main sensor attached to the back of the windscreen behind the rear view mirror. (this also serves the auto wipers) If someone could just cover each of the sensors in daylight, with the auto lights switched on, just to see whether it tricks the lights into thinking it's dark and turns them on, so as to confirm which sensor it is.

2. Confirm that the CH/LH lights only work when its dark regardless of whether they are turned on or not.

Thanks guys and sorry about the essay!
 
Still with you so far. If your sensor was hosed you would see the error all the time wouldn't you?

1. You can turn the dipping mirror off so I don't think it's the sensor in the mirror.
2. I'll test my lights for you when it stops raining!!!
 
Understood boggy. From the errors it would appear to me that there is a short in the wiring for your light sensor somewhere. This would explain why it works once and then fails after that. The DTC errors appear to prevent it from functioning again.

The sensor on the windscreen is the rain sensor. The sensors on the mirrored side of the mirror will be for the rear dimming. I'm nearly sure that the light sensor for the lights is in the center of the dash on one side of the center speaker grille. One of them flashes a red light when the car is locked, the other should be the light sensor.

There is also a light sensor in the instrument cluster which controls the backlighting on the dials - if you have the backlighting set to minimum and it is bright outside this sensor overrides the manual setting and sets the backlighting to the maximum. That's why if you drive with your lights on during the day and enter a tunnel the backlighting will dim.

Do the Auto Wipers still work when you have the CH\LH set to adaptation?
 
MarcQuinlivan said:
I'm nearly sure that the light sensor for the lights is in the center of the dash on one side of the center speaker grille. One of them flashes a red light when the car is locked, the other should be the light sensor.
Click to expand...

I'll test that for you...
 
Yes there is a sun sensor which should be to the left of the centre speaker grille. Part number 8P0 907 539 A 4PK. Do you have this?

The flat contact housing for this part is 8E0 971 832 and it is a black 4 pin connector.
 
Crikey, there's sensors everywhere!!!

MarcQuinlivan said:
Do the Auto Wipers still work when you have the CH\LH set to adaptation?
Click to expand...


I've just been to the car and changed a few things with Vagcom with the following results. It doesn't get any easier I'm afraid so here goes.

With the coding on "personalisation", the auto wipers do not work. With the coding on "light sensor", the auto wipers do not work either. (It's raining at the moment so I was able to test). I also had no fault codes after all scenarios. So that means the auto wipers are not linked to the "personalisation/light sensor" coding. I also tried the auto lights and CH/LH functions with both codings and the lights lit up both times even though it was light. Which questions whether the coding controls the light sensor part of the auto lights and CH/LH functions!!

Now, to add to this, there is another Byte that can be ticked on the first page called "rain/light sensor installed". When I tick this function/coding, the auto wipers work and the auto lights and CH/LH functions work properly. (but only for 1 time for the lights). I'm sure this is the sensor attached to the windscreen and by ticking/coding, it tells the car that it's there. My problem is that I get fault codes after using the functions and now, the warning light comes up my DIS.

My thoughts so far were that the rain/light sensor, attached to the windscreen, controlled the auto wipers (confirmed) but also "told" the auto lights and CH/LH functions whether it was light or not. However, if there are various sensors around the car, this may not be the case. Working it out has also been stumped by the fault codes I keep getting. Once I've checked my wiring I might be able to answer a few questions.

Wow, I've got a headache!

JohnS3, If you could confirm which sensor does what, that'll be a big help.
 
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