Communication Status: K-Line #2 Cannot detect Vehicle Bus

Hello, I am trying to clear an airbag light after I started car with seat removed. My Durametric software can see the immobilizer and the ecu, which i believe communicate on K-line #1 but I cant talk to anything else on the car. Durametric support says a wiring short or failed module on the K-line #2 bus.. Has anyone had this problem before? Is there a drawing of the topography the this system? Im looking for troubleshooting ideas.

Which model year are we talking? Did you replace the airbag and the wiring to the airbag? In general there is only one K-Line connection from the OBD connector to the car. Maybe a bus termination or ground problem.

No, I foolishly started car with seat removed� normally I should just be able to clear the code with my software �99 996 cabriolet

Have you used the interface for a while? I was sent 2 bad ones from Durametric before finally getting a good one that works. The first worked for several minutes before failing and the second wouldn�t communicate with the K1 bus. can you try the tool on another 996? That�ll make sure it�s not a tool issue. Otherwise there is a copy of the service manual and wiring diagram here- http://p914-6info.net/996%20Manuals.html

I was preparing to did deeper with probing and scoping the actual bus wires, and pulling modules until I see communication� but.. I caught some chatter, �98 era vw�s had similar problems when an aftermarket stereo was installed , it shorts one of the K-line bus wires in some cases�. I had heard radios can cause interference so I perviously tested by pulling the fuse to my radio.. I will dig deeper later ion as time allows and unplug my radio completely �

?OK, I have had some more time, I am getting 8.6V between pins 4 and 7 of the ODBD port, this is the K-line and ground. When I cycle the key it spikes then comes down. Whats the common things that go bad on the K-line Bus, or does the wiring itself develop issues? I

Durametric states a faulty air bag unit can bring down K2 bus. Also aftermarket electronics can do the same. You can check the K2 bus which resides on pin 3 of OBD socket. Check for voltage between pin 3 and ground, pins 4 or 5. With ignition on should be no voltage. Also should be no continuity.

I�m showing pin 7 to be the k line lead , this is consistent with obd2 standards �. Pin 3 goes just to the cluster � I�m wanting to make a list of everything plugged into the k lead, there is obviously something pulling my voltage down �

What I notice on the diagram is that pin 7 is the K1 bus which connects to the ecu, the tiptronic and the alarm modules. Where as pin 3 K2 bus goes to everything else. So if your having a problem resetting your air bag fault pin 3 should be your focus. You can drive to a dealer and have them use their scan tool to reset air bag fault, or send your cable back to Durametric for evaluation, Either one should tell you if your K2 bus is working or compromised. If you want to test yourself try the following: The airbag is on the second K-line, which is connected to pin 3 of the OBDII port. K-line idles high (bit "1"). When the scanner wants to send a bit "0", it pulls the K-line to ground using an unprotected transistor. If the K-line is shorted to +12v, that will kill the transistor when the scanner tries to pull that 12v to ground. To test if pin 3 is shorted to the +12v, connect a ~500ohm resistor between pin 3 and +12v, then another 50ohm (5w or hgher) resistor between pin 3 and the ground. Now measure pin 3. If it only has ~1v, your K-line is fine. If it's still at 12v, the K-line is shorted to 12v. Be careful the 50ohm resistor will get hot if the K-lime is shorted to 12v.

Its Getting Warm again, so I am going to get ready to open things up. So pin3 is the K-Line to most of the modules ( including the ones I need to talk to ) ? In theory, If there is a short, in theory can I unplug each module until the system talks again, and that's the bad module? And if all modules are unplugged, I have a wiring fault itself? I had to Reread all the info you gave me, but I will focus on pin 3 Update : I invested in PWIS and it doesnt talk to the modules either

Hi, Today I was able to measure pins 3 & 7.. double checking on both pins 4&5 for ground � I am reading nothing on pin 3 with the key off, and 12v with the key on� on pin 7 it�s constantly 8v does this help anyone wiser than myself ?

Update: ordered a foxwell NT530 just to reset the airbag� With 5 minutes of having it in my hand I was reading the airbag and the convertible top controllers� was able to clear codes but it didn�t look like the nt530 can do a roof calibration� So far� the foxwell does more than the durametric on my 99 c2 cab� so I have to officially retract any endorsement of durametric and say the foxwell will do great unless you have to program modules..

Update: After insisting, I was able to contact a new person� durametric did say that �99�s with cruise control didn�t communicate the same, I am happy to report they � repaired � my cable and now I have full access to every module in my car