[V8] ECU grounding, etc. - Check engine light

[Dave Saad]

On the MIL light, you probably have a short to ground near the  
footwell connector for the ECU or the connector behind the radio got  
grounded somehow.

Dave


On Oct 11, 2005, at 6:42 PM, Tony and Lillie wrote:

> ----- Original Message -----
> From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
> To: <v8 at audifans.com>
> Sent: Tuesday, October 11, 2005 3:43 PM
> Subject: Re: [V8] ECU grounding, etc. (abridged)
>
>
>
>> ... while I've found the wiring diagram to be pretty much literally
>> correct in its description of the connections and how they are  
>> made you
>> may well want to be a bit skeptical.  The wiring diagram may show a
>> direct wire connecting two points, when the connection may be a  
>> bit more
>> indirect.
>>
>> We've had the discussion here in the past ... proper grounding can  
>> be a
>> very tricky thing ... it is better to keep the grounds for sensors
>> separate for grounds for things that the ECU drives ... but then  
>> ground
>> needs to be connected together somewhere.  The example I always come
>> back to is the two grounding lugs that attach to the back of the  
>> engine
>> below the left cylinder bank ... I've never had the need nor time to
>> investigate, but I fully expect that one of the ground lugs  
>> provides the
>> reference for the sensors and the other for the driven components ...
>> but through the Kostal connectors multiple signals called "ground"  
>> pass
>> through different pins.  There may also be splices within the  
>> confines
>> of the wiring looms ... if you've got a more involved grounding  
>> problem
>> you're going to have to dig in and understand this sort of thing more
>> completely ...
>>
>> Steve B
>> San Jose, CA (USA)
>>
>
> This is something I've wondered about for a while. There are three  
> different
> ground paths shown in the manual. I've been curious about where  
> they get
> their grounds from. I figured in the ECU, but don't know for sure.  
> If they
> are external, what is the harm in finding the solder joints and  
> attaching
> another wire and running it to a good ground?
>
> What leads me to this is I have a permenant Check-Engine light in  
> mine. The
> code pulled is a bad ground for the O2 sensor. As it has a new four  
> wire,
> and I've run an additional ground from the body to the engine, I'm  
> at a
> loss. Oh, it also had the light with the 3-wire original, and with  
> the last
> 4-wire replacement. And, I've changed the ECU (different problem).  
> So, does
> anyone have answers? Are those grounds terminating at the back of the
> engine?
>
> Tony Hoffman
>
> _______________________________________________
> Audifans V8 mailing list
> Send posts to: mailto:V8 at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/ 
> listinfo/v8
> Have an Audi V8 question?  Check the Audifans Knowledgebase!
> http://www.audifans.com/twiki/bin/view/Audi/V8
> Have a V8 answer? ... Please help others by adding to the KB ...  
> all contributions welcome!
>