Hi

We have this mini with the alternator light on permanently on, checked with autologic and found plenty of fault codes all over wiped clean and none returned. Not looking for a silver bullet but if anyone can explain how the system works e.g the 3 wires going to the ecu and what they actually do i can then carry out my own tests. We have bosch esi, autovista for tech info but none seem to give the info i require, so any help most welcome

Thank you terry taylor

3 wires going to ecu smart charge? year model engine and make of alternator for wiring diagram

Have you checked fuses in left footwell fusebox.?I think you will find one of the wires is a battery sense signal from f/box.

From what I can see and make out

Pin one is a fused supply to alternator
pin two is to instrument cluster
Pin three is activation from ecu and is a square wave 5 to 95% dc.

There is some other conflicting info though that the alternator has two interfaces to the dde, activation and acknowledgement, and the dde is responsible of activating the battery warning lamp and there is no physical connection to the warning lamp from the alternator. I'm guessing pin two would then be acknowledgement to ecu and guessing it would be %DC also.

Maybe this will help

Fixed

Short circuit in alternator disconnect 3 wire plug and dash light goes off.

Thanks everyone

terry taylor