Is it possible to repair the "Computer" (ICU)

[jlagnese at massed.net]

Make sure to clean all grounds for the ice. In my experience those fail with a 
poor ground.
John
---- Original message ----
>Date: Wed, 24 Aug 2011 13:08:05 -0400
>From: Marc Boucher <mboucher70 at hotmail.com>  
>Subject: Is it possible to repair the "Computer" (ICU)  
>To: Tony Hoffman <auditony at gmail.com>, "quattro at audifans.com" 
<quattro at audifans.com>
>
>All of the testing I've done indicates that my car's failure was the ICU.  The 
wiring and the grounds leading to both the IGnition unit and fuel injection unit 
all check out.  Can provide more details after work when not typing on my 
iphone.
>
>Similarly, the ICU's failure to energise the ISV, And most of the items in the 
Output tests also point this way.
>
>Are there any replaceable parts in the ICU such as resistors and transistors 
or is it all proprietary IC's ?
>
>Thanks
>MC
>
>On 2011-08-19, at 9:55 AM, Tony Hoffman <auditony at gmail.com> wrote:
>
>> Marc, The schematics I have show this:
>>  
>> One of the ECU grounds goes to the left side behind the dash. One goes 
to the intake manifold, this is the main one. It is a Brown/white wire. There is 
one that goes into the engine wiring harness, and is soldered to several 
others. That one is brown/red.
>>  
>> The Ignition Control unit is grounded in the engine waring harness via 
brown/red. It also has a ground that is brown (it's main ground) that goes to 
the base of the right side A pillar.
>>  
>> Those are the first things you need to check. The hall sender has a 
brown/white, a green/white, and a red/black. The red/black is the 12v feed to 
it. The brown/white is the ground signal to it. The green/white is the 5v 
switching signal. If they grounded the brown/white there is probably a 
problem in the ICU or with it's ground.
>>  
>> HTH,
>> Tony
>> 
>> On Thu, Aug 18, 2011 at 10:58 PM, Marc Boucher 
<mboucher70 at hotmail.com> wrote:
>> I'll be definitely going at it now with a volt-ohm meter to try and get it 
back to match the schematics.
>> 
>> If you had to guess, were they trying to establish ground from the hall 
sender, and they meant to connect the "green-white" cable depicted as "0" 
on the schematics to the engine block, rather than the brown-white labelled 
"-" ?
>> 
>> The schematic shows that the IGN booster has a brown-white cable 
which is connected directly to ground.  If they suspected a ground problem 
involving the IGN booster, why not ground the IGN booster, not the hall 
sender?
>> 
>> I realize that this is beside the point, since the main point is to get it back 
to match the schematics.  But I thought it would be useful to try and 
understand what they did and why they did it, since it DID solve the problem 
of the car not running.
>> 
>> Thanks again,
>> MC
>> 
>> --------------------------------------------------
>> From: "Huw Powell" <audi at humanspeakers.com>
>> Sent: Wednesday, August 17, 2011 10:34 PM
>> To: "Marc Boucher" <mboucher70 at hotmail.com>
>> Cc: <quattro at audifans.com>
>> Subject: Re: The Outcome (Part 2) of "Audi just shuts off no warning 
while driving and won't restart"
>> 
>> 
>> 
>> Looked around to see what exactly they did to solve the "ECU ground"
>> problem. *It appears that they cut the brown and white wire wire coming
>> from the Hall Generator, and bolted it to the engine block in order to
>> act as a ground. The schematics show that wire should go directly to pin
>> 10 on the ICU.*
>> 
>> Nice work.  Striped brown wires are *switched* grounds.
>> 
>> **
>> Their invoice says that they "Check wiring from ignition distributor
>> coil and ignition ECU, Determine ground signal wire from ECU not
>> functioning, Repair ground wire". According to the schematics, red-black
>> wire is "+", the Brown-White is "-" and the "green-white" is "0". Does
>> that make sense, to connect the brown-white wire to the engine block for
>> ground? If not, could that have defeated the ISV ?
>> MC
>> 
>> If it made sense, it would have come that way from the factory.  It might 
be time to dig out or buy a VOM and do some checks yourself.
>> 
>> 
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>> 
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