# "No response from controller" Airbag light, need K-Line troubleshooting help.



## 8up (Mar 1, 2011)

Hey guys, I have a 1999 Passat with a 1.8T 5 speed. We just bought the car in January. We have done alot of work to the car to get it right, but it has an airbag fault light on. The safety inspection expired in January and will not pass with an airbag fault light. I purchased a Ross-Tech Vag-Com cable but when I try to read the faults I get a "no response from controller". I checked the voltage to the controller and it was OK. I also checked for continuity from the OBDII K-line to the comm port at the airbag controll module connector. After that I ordered a used controller from ebay. It has the same issue, no response from controller.

I have touched base with Ross-Tech and they have been great, but i really need to get the Bentley repair manual. I have the Haynes, but it doesn't really show much about the K-Line system. I was wondering if someone could give me some guidance until I can get my manual next week?

I read on this forrum that when the airbag light stays on continuously after the ignition switch is turned on (which it is), that it's possible that the airbag module is not communicating with the instrument cluster, any thoughts?


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## vwemporium (May 27, 2002)

::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## 8up (Mar 1, 2011)

Here was my initial autoscan.

Thanks for the reply.

Wednesday,16,February,2011,14:40:27:34716
VCDS Version: Release 10.6.3
Data version: 20101206



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 3B - VW Passat B5
Scan: 01 02 03 08 15 16 17 19 35 36 37 46 47 55 56 57 58 75 76 77


Mileage: 172650km/107279miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 058-907-55x-AEBN.lbl
Part No: 8D0 907 557 P
Component: 1.8L R4/5VT MOTR HS D07 
Coding: 06001
Shop #: WSC 05311 
VCID: 3D7FC6DA1DF7

1 Fault Found:
18010 - Power Supply Terminal 30: Voltage too Low 
P1602 - 35-10 - - - Intermittent
Readiness: 0110 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8E0-614-111-EDS.lbl
Part No: 8E0 614 111 B
Component: ABS/EDS 5.3 FRONT D10 
Shop #: BB 24332 
VCID: 1D3F265ABD37

No fault code found.

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Address 17: Instruments Labels: 3B0-919-xxx-17.lbl
Part No: 3B1 919 930 F
Component: B5-KOMBIINSTR. VDO V01 
Coding: 06242
Shop #: WSC 00000 
VCID: 2B5BF882F383

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 1J0-959-799.lbl
Part No: 1J0 959 799 AJ
Component: 63 Zentral-SG Komf. 0001 
Coding: 04096
Shop #: WSC 05311 
VCID: 860DE93688A1

Part No: 1J1959801D
Component: 63 Tõrsteuerger. FS0002F 

Part No: 1J1959802E
Component: 63 Tõrsteuerger. BF0002B 

Part No: 1J4959811D
Component: 63 Tõrsteuerger. HL0002r 

Part No: 1J4959812D
Component: 63 Tõrsteuerger. HR0002r 

6 Faults Found:
00943 - Heated Exterior Mirror; Driver Side (Z4) 
35-00 - - 
00929 - Locking Module for Central Locking; Front Passenger Side (F221) 
27-00 - Implausible Signal
00944 - Heated Exterior Mirror; Passenger Side (Z5) 
35-10 - - - Intermittent
00930 - Locking Module for Central Locking; Rear Left (F222) 
27-00 - Implausible Signal
00935 - Electric Window Motor; Rear Right (V27) 
62-00 - No or Incorrect Adjustment
00931 - Locking Module for Central Locking; Rear Right (F223) 
27-00 - Implausible Signal

-------------------------------------------------------------------------------
Address 56: Radio Labels: 1J0-035-18x-56.lbl
Part No: 1J0 035 180 D
Component: RADIO 3CP 0001 
Coding: 00401
Shop #: WSC 05311 
VCID: 20411FAE8A45

1 Fault Found:
00852 - Loudspeaker(s); Front 
36-00 - Open Circuit

End ---------------------------------------------------------------------


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## vwemporium (May 27, 2002)

Check::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## stan067 (Feb 25, 2010)

I believe?
DLC pin 7 is green this is “K” line. Stay green till internal connection (splice) in instrument wiring harness.
Comes out of this internal connection (splice) as a Green/Brown wire going to terminal #9 of airbag module.
Also check power and ground at air bag module. 
Ground brown wire terminal #6 airbag module. Comes from left side dash and is same ground used by driver & pass airbags and is there always.
Power Black wire terminal #5 air bag module. Comes from ignition switch and has power with key on or cranking starter.
You are missing one of these. Also use the old module because most likely it not your problem and will be coded right for your car. This being a Passat look for water under drive side front rug! This is where the CCM is and it has a wire going to the airbag module. These water damaged CCM are a major common problem and should be checked! Also the pass side front rug too, this is the location of the TCM big money there. Do your self a favor and get to both the CCM & TCM. Better safe then sorry. Sorry, no TCM you have a std. trans
Good Luck


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## Dana @ Ross-Tech (Sep 15, 2009)

Does this car have the (fancy volume and CCS) steering wheel buttons? I doubt it on a manual trans 1.8T, but if it does the 16 module should communicate.


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## 8up (Mar 1, 2011)

Thanks for all the replies. I ordered my Bentley repair manual from Ross-Tech the other night. I should be getting it any day now. I am looking forward to getting this problem solved. I haven't had a chance to try all the suggestions yet, maybe over the next couple of days though.


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## 8up (Mar 1, 2011)

Well, I got my repair manual DVD yesterday and checked things out. I touched base with Ross-Tech and got them to go over some things I spoke with them about last week(now that I could see the drawings they were refering to). I have heard the warnings about using a Digital Multi meter for checking out these systems.

* I verified that I have ignition voltage at the airbag module connector on pins 5 & 6 of T50 (had 11.7 volts) 
* Verified continuity through pin 6 on T50 to chassis.
* Verified continuity the OBDII port pin 7 both ways.... up to the blue connector T32A pin25 up in the instrument panel and down to the airbag module T50 pin 9. And from T50 pin 9 all the way up to T32A pin 25.
* Verified continuity from the airbag module T50 pin 30 to the blue connector T32A pin 6. 

I did not mess with the CCM. What effect would this have on the airbag controller?

It appears to me that everything checks out ok. It seems very possible that the used airbag module I bought is bad too. Whats everyone's take on this? Where do I go from here? The dealer wants like $760.00 for a new module.


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## Dana @ Ross-Tech (Sep 15, 2009)

8up said:


> I did not mess with the CCM. What effect would this have on the airbag controller?


Any of the diagnostic capable modules in this car could be crashing the communication to the Airbag module. If you do not have steering wheel controls (address 16) then I would recommend unplugging each module one at a time to see if the Airbag module will communicate. Since the 46 module has faults, and they are known for water ingression/corrosion, I would personally start there.

If you get to the point where all other modules are disconnected and the module will (still) not communicate...you may actually have 2 faulty Airbag modules. For the cost of the replacement module I would go that route, confirming the diagnosis, before purchasing one.


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## stan067 (Feb 25, 2010)

CCM get water soaked known problem. It has a wire going to the airbag module and this could short out the Airbag module. The chance that you have 2 bad airbag module could happen but unlikely. Get a look at the CCM disconnect it and try to log in to airbag module. Dana has told you to start here also. Good Luck


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## 8up (Mar 1, 2011)

I removed the driver seat this afternoon and accessed the ccm and disconnecterd it. The VAG-COM would still not connect to either airbag controller (tried the old and the new/used one). The area under the driver side carpet looked real good, no sign of water. I did check the continuity between the airbag module conector and the 23 pin connector at the CCM while I was there.

This poor car is torn to pieces from removing everything to gain access to these parts, hope I can get her back together.:banghead:

I'm not sure what other modules to disconnect? Instrument and ABS? I was going to disconnect the ABS module but the manual said it was to be done after the hydraulic unit was removed, not sure about all that. I think I am ready to throw in the towel.


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## mwebb (Apr 19, 2008)

*see if the scan tool will toggle the K line at the Airbag module*

you really should do this with a scope 
but 
a DVOM may do if it can read duty cycle , 

connect to the K line at the airbag module , then attempt to ping the airbag module with the VCDS scan tool ,
a scope will show the scan tool toggling the k line to ground and then the airbag module will respond , of course if any other module connected to the K line the responds the results will appear the same 
the ground between the K line reply and the scan tool ping will be different so you will be able to see the response , 
the scan tool will ping first if no response it will try again , the answer from the module will be different , ever so slightly .... 
or 

there will be no reply , if you see the scan tool ping , but no reply from the module 
and the module has power and ground 
it is KA KA 

unless you enjoy chasing your own tail with out ever catching it
NEVER use an ohm meter on a broken car , as in never .
use voltage drop testing on the suspected circuit instead .

door modules on module 46 can sing , drowning the network in a never ending burst 
ABS modules can shut down communication on the k line as well 
just disconnect the ABS module , there is no drama involved or special procedure , just remove the connector .... the connector to the module near the PS reservoir 

if connected to the K line
a DVOM will show a glimmer of duty cycle activity when pinged , but there will be no way to differentiate between module and scan tool
if the DVOM does not have a duty cycle or pulse width function , you can not use it for this 
==============================
you have a low system voltage code 
verify battery condition and make sure the alternator is charging correctly with less than 200 millivolts of AC present at the battery with engine at idle and hi beams and heater blower maxed . 
high value alternator ripple will show on the K line and confuse everything 

Module 15 does not like low system voltage and will usually code before any other module for this condition


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## stan067 (Feb 25, 2010)

From what you posted it does look like the airbag module is bad. It is not likely to have 2 bad modules though? But is possible. 

You can disconnect the ABS without any problems I have done it many times. I also own a 99 Passat 2.8 liter 30 valve and I had to send the ABS module out for rebuild due to false wheel speed sensor codes. So you can disconnect the ABS and try to scan for the airbag module.
You can also disconnect the cluster and try.
I am sorry that you went thru the work to get to the CCM for no reason. But it had to be done! This is a very common water problem and had to be eliminated.
I can not tell you to go buy the dealer new airbag module that’s too much cash for me to recommend without seeing the car. I also have not seen any bad airbag modules for no reason.
I would also try load testing the power and grounds at the airbag module. If you have a weak connection it will show voltage with a meter but loose the voltage under a load. DVOM have very little load! Rig up a low beam head light with 1 power & 1 ground wire and use this as a test light. If the ground and powers at the airbag module light the low beam that’s a few amp load and if it lights you know they are strong power and grounds. Just because a DVOM says 12 volts it’s not a loaded 12volts. 
Good Luck


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## 8up (Mar 1, 2011)

I disconnected the ABS, ECM and the instrument cluster this evening and tried to connect to the airbag module, still no luck. I am throwing in the towell and taking it to the dealer. 

I will keep you informed and close out this post with the solution. Nothings worse than searching forrums and finding out that people never followed up with an answer.


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## stan067 (Feb 25, 2010)

Sorry you can't find the problem but it isn't for lack of trying!!!! Did you load test the power and grounds at the module with a head light bulb test light that draws a few amps? Again sorry I got time in this with you. Took me time to type and look up wiring diagrams, so I am not happy either. You said nothing worse then no body following up with the fix on forums you searched. Well just be sure you follow up with the answer from the dealer. Forums are limited to what they can help with and you still haven't load tested or answered if you did the power and grounds. I also know the CCM wasn't soaked with water but it took you a long time to actually look. We weren't tell you to look because we wanted you to waist your time. Again real sorry it wasn't a common problem. Post the fix when you know it. Good Luck


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## 8up (Mar 1, 2011)

I load tested the power to the module today. I have a 12vdc light fixture for my boat, it has two 1141 bulbs in it. I connected it directly to my battery first to see what kind of current draw it had. Looks like it had about a 2.5 amp current draw. I then connected it to pins 5 and 6 of the airbag control module connector (with it disconnected from the module). When I turned on the ignition, it would not even try to light and the voltage(at the light connection) dropped to 0.00vdc. So.........what do you think is causing this issue? Do I have a glimmer of hope that the module might be OK? 

BTW the car has an aftermarket Interstate battery. For what it's worth.....I tried the battery out of my truck to see if it made a difference (not a great connection) but it didn't.


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## 8up (Mar 1, 2011)

*Found the problem!!!!!*

Tried a couple of things today after talking to Dana at Ross-Tech. Connected the test light back up to the airbag module, this time I ran a wire all the way back to the battery. 

First test was to connect the wire to the neg terninal and ground the light back to the battery and connected the power lead of the light to pin 5 of the airbag control module(with it disconnected from the module). No light:thumbdown: 

Second test was to power the light with the wire from the battery connected to the pos terminal and grounding the light through pin 6 of the airbag control module. This was to check the ground wire. Got light!:thumbup: 

The ignition power has to pass through connector T10p pin 2 to get to the airbag control module. This is a 10 pin connector, yellow in color located at the connector station at the base of the right side a pillar under the glove box. Removed the cover at the a pillar (1 screw) and exposed all the connectors. To my suprise, I see the connector about half unplugged. I re-seated the connector. I then tried the light test again, this time using the power and ground from the airbag control module connector. Got light! 

Reconnected the airbag module, communicated fine and spent the next few hours putting the interior back together. Thanks so much for everyones help. Thanks Stan067 for insisting I try this test light idea. Could have been an expensive lesson learned. Needless to say.......I am thrilled!


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## stan067 (Feb 25, 2010)

I am very happy for you!!! I am also happy for myself! After making you check the CCM for water and your growing anger, I felt bad. But like I said it had to be eliminated. I also didn’t think 2 air bag modules would have the same exact problem. Something had to be taking the “K” line down or it was a power & ground problem. You were capable enough that you did all everyone suggested which doesn’t happen to often in forums. You also seemed to have a good grasp of electricity and know how to use a DVOM, again doesn’t happen to often in a forum. I also knew it was something real stupid & simple causing your problem. It was just finding it that was a problem. I trusted your work and you ability from reading your posts enough that I knew you were doing the tests right. Just tearing the car apart like you did wasn’t easy. Then after all the testing of the wires and everything testing fine. I couldn’t figure out why? It made no damn sense and I started to look like an idiot. I also knew it had to be a “K” line problem or power & ground problem. I then thought load test the power & grounds and if they were good even I give up at that point. So I told you how to make a test light with a head light bulb that draws a few amps and load the power and ground. (I laughed hard at your 12v boat light with 1141 bulbs) Then you posted you give up and I could tell you were mad at everyone the car, me, the forum even your wife at this point. But you never load tested the circuit. Dude I was pissed at that point because you didn’t do it and said screw it. I wanted to bitch at you because you were not listening… But I replied nice yelled a little because you didn’t load test, and told you to post the fix when the dealer got done with it. Because that’s all I really wanted the fix! Nothing burns me more then all this time and no answer! I hate that!!!! I really didn’t look at the forum for a few days because I thought this one a lost cause, you gave up. Today I was surprised to find you listened and gave it another shot. I guess you hate failure as much as I do. LOL Once you told me it had 12 volts then went to 0 volts with your boat light I knew you found the simple stupid problem. Under load you lost the power, bad connection. These are tuff to find when the DVOM say’s there is voltage and really there isn’t. Do your self a favor and make up a test light with a head light bulb and put it with your DVOM because you will always load test now. I know you are happy and you also made my day. Real glad you didn’t give up and you listened. You will use this trick for the rest of your life and it’s a great test I’ve used it for years and it saved my ass more then a few time. Man when you found the bad power connection I bet you were dancing. Feels good doesn’t it? Good Luck


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## 8up (Mar 1, 2011)

I wanted to post of pic of the area where the loose connection was. This is the passenger side lower "A" pillar under the glove box. The specific connector is not really visible in this pic.


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