Register a free account today to become a member!
Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

172 alternator problem...

  bmw m3, clio sport
Okay, the battery / stop light came on the other day, was close to home so tried to make it back, car died about 200 yards from home, alternator whining and smoking just before dying. Pushed the car back home and got a second hand "fully working alternator" . Fitted the alternator and fired the car up. Battery light stayed on but then went off when revving the car. Used a multimeter to check the voltage. 12.5v just on battery and then between 13.2v and 14.2v depending on revs, which tells me the alternator is doing its job. However the battery / stop light now stays on permanently.

The alternator gets incredibly hot, water bubbles and steams as soon as it comes in to contact with the casing. (just tried a little drop), and the alternator also seems to whine. I cleaned the the plug with one wire out as it was a little corroded, no joy. There is 10.8v to the wire in the plug, and full continuity to the plug at the back of dashboard.

Seems unlikely that its the alternator that's at fault again, although this is possible.

Does anybody have any idea why the battery light would be on even though the alternator seems to be working fine. Also getting stupid hot. Is the regulator in the ECU or soley withing the alternator ?



ClioSport Club Member
Alternator. The excite part of the alternator, isn't working, hence why its getting hot, and failing to charge at low RPM, at high RPM it just starts charging anyway.

Same reason the battery light is on too, as the circuit internally isn't working.