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

[Huw Powell]

Can you run down all the tests and observations you have made so far in 
one email when you are at your keyboard again?

And keep the year and model and engine code in the thread as well...

On 8/24/2011 1:08 PM, Marc Boucher wrote:
> 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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