I have an August 1992 (MY93) AAN loom in my hands right now - just here for a check up and to verify as many plugs and wires line up with schematics as possible... rarely a certainty with Audi diagrams... and there were changes in later years of course.
The AAN loom is easy to spot first of all cos it carries a '4A0' prefix on the part number label and the ECU plug has pin 32 installed for the digital boost display - i.e. the middle row of pins has none missing.
It does NOT however have pin 46 installed (unlike ABY & ADU) which is for the F76/R terminal from the MFTS signifying an alarm about excessive water temperature. This does line up with AAN schematics as correct but I always wondered if it was fitted anyway.
On the ABY/ADU, using this pin as a high temp alarm - the ECU cuts off active boost control as a safety measure...
On the AAN all the F76/R pin connects to is the HVAC/climate system to shut off the compressor during such high temperatures. Not ideal... especially if the ECU ends up running some version of ADU software as you are missing this safety feature.
Fortunately, it is fairly easy to insert a new pin into the ECU plug and retrofit this function if you wish... What I normally end up doing is splicing in a wire inside the ECU and hooking it up to a sneaky 'valet' mode switch that limits boost to mechanical pressure... also known is spouse mode or eco mode - though remember it won't work on AAN code.
The AAN loom is easy to spot first of all cos it carries a '4A0' prefix on the part number label and the ECU plug has pin 32 installed for the digital boost display - i.e. the middle row of pins has none missing.
It does NOT however have pin 46 installed (unlike ABY & ADU) which is for the F76/R terminal from the MFTS signifying an alarm about excessive water temperature. This does line up with AAN schematics as correct but I always wondered if it was fitted anyway.
On the ABY/ADU, using this pin as a high temp alarm - the ECU cuts off active boost control as a safety measure...
On the AAN all the F76/R pin connects to is the HVAC/climate system to shut off the compressor during such high temperatures. Not ideal... especially if the ECU ends up running some version of ADU software as you are missing this safety feature.
Fortunately, it is fairly easy to insert a new pin into the ECU plug and retrofit this function if you wish... What I normally end up doing is splicing in a wire inside the ECU and hooking it up to a sneaky 'valet' mode switch that limits boost to mechanical pressure... also known is spouse mode or eco mode - though remember it won't work on AAN code.
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