Hey all, I am finishing a 4.2 motor swap and I cannot for the life of me figure out which pin on the ECU controls the MIL/CEL on the dash.

The whole car has been gutted and rewired. I have the pin on the dash side, need to get the pin on the ECU. The lamp control is not detailed on the wiring diagrams I have found and I'm stuck.

ECU is a ME7.1.1 box (4D0907560CE) running the euro S6 559E flash. Help, please! Thanks!

(FYI ME7.1 a6 4.2 uses pin 48. On ME7.1.1 that pin is allocated to another device)

So after a LOT of testing and searching, I found the answer to my question .... posting so someone else doesn't have to do all this searching too.

The A6 cluster from 98-99 is non-CAN. 00+ is CAN for the CEL on the cluster.
(source: https://www.audiworld.com/forums/a6-s6-c5-platform-discussion-7/understanding-differences-between-audi-a6-clusters-compatibility-issues-2798354/)

My 01 S4 cluster is non-CAN, but the S6 ECU I'm running sends the CEL over CAN. What I'm going to have to do is use an 00+ A6 cluster and connect the CAN bus together. This should get me the MIL I'm looking for so I can pass our local emissions and get this race car legally on the road.

That did it, macxxx. THANKS! Got the CEL working (err, turning on and off correctly when DTC's present), communication with the cluster got rid of the "no message from TCU" powertrain bus fault too.