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Just consolidating some info for future reference
Our 20VT engines are controlled by a Bosch Motronic ECU located in the passgenger footwell, under the carpet, by the firewall. The power to this ECU is two-fold. There is a 5 Amp constant power to pin T55/18 of the ECU maintains the ECU memory (what it has learned/adapted from your driving habits) and 15 Amp or 20 Amp switched power to Pin T55/27 of the ECU that leads to power of the ECU and the ignitions coils (or the N152 ignition transformer in the case of the 3B).
AAN ECU power sources:
The 5 amp constant source is in the red fuse holder (S26 for the UrS4s and S102 for the UrS6s). The switched power is in the yellow fuse holder, S64 for the UrS4s and S115 for the UrS6s):
3B, ABY and ADU:
Same thing re: 5 amp constant ECU power and 15/20 Amp switched power.
The 5 amp is in the S27 fuse holder under the "Motor" cover; the 20 amp switched power is in the S32 fuse holder at the right side of the fuse/relay box:
3B ECU power wiring:
Not sure why this diagram doesn't show the switched power S32 fuse to ECU pin T55/27. It shows the S27 constant power fuse to ECU pin T55/18:
Diagram from a VAG 3B self-study guide via S2central.net (thanks Paul)
ABY and ADU ECU power wiring:
Our 20VT engines are controlled by a Bosch Motronic ECU located in the passgenger footwell, under the carpet, by the firewall. The power to this ECU is two-fold. There is a 5 Amp constant power to pin T55/18 of the ECU maintains the ECU memory (what it has learned/adapted from your driving habits) and 15 Amp or 20 Amp switched power to Pin T55/27 of the ECU that leads to power of the ECU and the ignitions coils (or the N152 ignition transformer in the case of the 3B).
AAN ECU power sources:
The 5 amp constant source is in the red fuse holder (S26 for the UrS4s and S102 for the UrS6s). The switched power is in the yellow fuse holder, S64 for the UrS4s and S115 for the UrS6s):
3B, ABY and ADU:
Same thing re: 5 amp constant ECU power and 15/20 Amp switched power.
The 5 amp is in the S27 fuse holder under the "Motor" cover; the 20 amp switched power is in the S32 fuse holder at the right side of the fuse/relay box:
3B ECU power wiring:
Not sure why this diagram doesn't show the switched power S32 fuse to ECU pin T55/27. It shows the S27 constant power fuse to ECU pin T55/18:
Diagram from a VAG 3B self-study guide via S2central.net (thanks Paul)
ABY and ADU ECU power wiring: