# Audi A4 - cant connect to car's data link(ECM)



## jam1 (Mar 28, 2003)

I recently bought an 1998 Audi A4, for a reasonable price. The car hasn't ran in 1 year and so I brought it home put my charger on it, jumped the battery but I forgot that I had the charger set to deep cycle. After it started I notice that i had no power to the radio and the air bag light, abs light and check engine light was on. So when i went to use my scan tool to see why these lights are on, the scan tool is acking for me to turn on the ignition which is already on. I've used this tool on my 1998 jetta VR6 and my 2005 Audi A4, but it's cant communicate with the ECM. 
Does anyone know if the radio or ignition switch has anything to do with my problem? The radio fuse is fine but I dont know about the one behind the radio...
Thanks


_Modified by jam1 at 8:41 PM 4-29-2010_


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## jam1 (Mar 28, 2003)

*Re: Audi A4 - cant connect to car's data link(ECM) (jam1)*

Anyone???

Does anyone know if the this car uses a k-line? And power needs to be to the radio to be able to complete the K-line circuit?


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## O_o (Nov 12, 2009)

*Re: Audi A4 - cant connect to car's data link(ECM) (jam1)*

I don't know, but my guess is that your ignition switch is fried. It just seems too unbelievably stupid that the OBD should depend on the stereo.
You might have better luck in the B5 forum.


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## jam1 (Mar 28, 2003)

*Re: Audi A4 - cant connect to car's data link(ECM) ()*


_Quote, originally posted by ** »_I don't know, but my guess is that your ignition switch is fried. It just seems too unbelievably stupid that the OBD should depend on the stereo.
You might have better luck in the B5 forum.

thanks


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## tryin2vw (Dec 30, 2006)

*Re: Audi A4 - cant connect to car's data link(ECM) (jam1)*

Also check fuse 14. Is it an aftermarket stereo? If so, disconnect the K wire, or whole unit for now, to see if that improves things. Also a bad ABS module has been known to cause scan problems. You may need yours rebuilt.


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## jam1 (Mar 28, 2003)

*Re: Audi A4 - cant connect to car's data link(ECM) (tryin2vw)*


_Quote, originally posted by *tryin2vw* »_Also check fuse 14. Is it an aftermarket stereo? If so, disconnect the K wire, or whole unit for now, to see if that improves things. Also a bad ABS module has been known to cause scan problems. You may need yours rebuilt.


it's an OEM radio, the person I bought the car from said that the abs light is due to a disconnected abs sensor, haven't had time to check it yet.


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## MDpvC (Jan 12, 2008)

*Re: Audi A4 - cant connect to car's data link(ECM) (jam1)*

it could very possibly be the battery just being dead, or alternator. when my alternator went a few days ago i was driving and it started desplaying the exact same symptoms, then it just died. i'd say jump it from another car, when mine died my charger didnt do sh it. i had to jump it from my girlfriends rabbit.


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