FW: MAC-14 Diagnostics

Ben Swann benswann at comcast.net
Wed Sep 26 20:54:18 PDT 2007

From: Ben Swann [mailto:benswann at comcast.net] 
Sent: Wednesday, September 26, 2007 10:42 PM
To: 'suffolkd at aol.com'; '200q20v at audifans.com'
Cc: 'quattro at audifans.com'
Subject: RE: MAC-14 Diagnostics


I have the ugly connector and VAG-COM cable.  I also have it wired to do either CEL blink or VAG-COM or both, but something is not right.


So far it seems that the pin 33 should be giving 12V+ and it doesn’t.  Also, why when initiating diagnostics does the engine cut.


There is no fuse per se. as there was really no need to install the fuel pump relay.  I am wiring without a fusebox – everything goes into the glove compartment.  My versions of power supply relay(s) do basically what the Bentley diagram have.  If you study the diagram, there is really no need for a Fuel pump relay since 1) MS can do the fuel cut  2) I have fuel pump relayed on with ignition until I get the other stuff squared away 3) the fuel pump only supplies power to devices mostly specific to CIS and now essentially removed – ISV, OX heater, etc. have separate relay.


It make sense if you think “how would I wire this if installing engine from scratch and want to run it on a stand instead of in a car.”  




From: suffolkd at aol.com [mailto:suffolkd at aol.com] 
Sent: Wednesday, September 26, 2007 10:22 PM
To: benswann at comcast.net; 200q20v at audifans.com
Cc: quattro at audifans.com
Subject: Re: MAC-14 Diagnostics


Do you need the 2x2 ugly connector?

or are you going to install a check engine bulb in the dash and try to blink out code with a fuse?
-Scott by BOSTON


-----Original Message-----
From: Ben Swann <benswann at comcast.net>
To: suffolkd at aol.com; 200q20v at audifans.com
Cc: quattro at audifans.com; 'Ben Swann' <benswann at comcast.net>
Sent: Wed, 26 Sep 2007 10:14 pm
Subject: RE: MAC-14 Diagnostics

I think we are confusing things here.  I am simply trying to blink out codes for now – should at least be able to do this.  In fact I know it can be done and have done it before, just not on a transplanted MC-2/MAC-14 setup.  And of course this is the MC-2 10V CIS hybrid not the 3B 20V efi , but there are many who subscribe to this list because the ‘89 and ‘90 200Q are more similar to the ’91 20V despite that the engine is Motronic EFI instead of the hybrid variant that was MAC-14.  Furthermore the diagnostics techniques spelled out in the Bently for the MC-2 are actually quite similar to the 3B probably closer “procedure-wise” than the MC-1.  But still the option to blink out codes is there – just sometimes need to install a check engine light, according to procedure.  I have the feeling some other things have been left out and because the procedure calls for using specialized VAG equipment, one needs to guess at what these things actually are.  I also think there may be errors or omissions in the diagram.


With that, it would also be nice to use VAG-COM as the com interface is supposedly there.  So you are saying that you have not been able to use VAG-COM on an MC-2/MAC-14?  I haven’t either, but Bentley and SJM suggest it can be done.


At the very least, I should be able to blink codes like on the MC-1.



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