Xmas tree dash Lights

[paultv]

Started her up yesterday...normal dash lights when ignition on, but after starting I had a glorious xmas tree of lights flickering and changing as I dropped the hand brake. ABS, brake wear sensor, ignition, oil and hydraulics all in various states.

The service indicator was working correctly.

Driving the car gave me a clear dash but with a strange mpg meter behaviour.

Checked the SI lithiums...both at 3.1 volts..so ok.

Checked charge voltage at battery with engine running...nothing...sitting at 12.6 volts regardless of engine revs.

Put all the lights on for ten minutes to discharge the battery...re started...battery voltage did not rise to a charge level...should be a good 14 volts.

Pulled out the AFM and removed the regulator from the alternator...about 4mm on the brushes left.....cleaned them and pulled them out as far as possible...re installed..battery now charging and dash is all sensible.

Ordered a new regulator...7 euros...job done.

Its 6 years since I fitted the last regulator so they dont last that long...maybe I should buy a better brand!!

Paul

[Brianmoooore]

There's a legal requirement for certain warning lights on a car to have a 'test' function at start up, to prove they are working. On the E30, the test is switched on when the ignition is turned on, and turned off when the voltage on the small blue wire from the alternator reaches a certain threshold voltage. It sounds like your alternator was managing to generate a voltage just on the borders of this threshold.
The quality of carbon used for brushes does vary. but if the copper commutator face was roughed up by a previous brush failure, then the life of replacement brushes will be reduced.

[paultv]

Thought i would post a shot of the worn regulator brushes that were giving me trouble.

PSX_20200813_153921.jpg

Not sure what the tolerance is with these but the contact area to the slip rings was reduced giving almost no charge and I couldn't pull the brushes out any further.


Paul

[Brianmoooore]

Ends of brushes are even and not too badly grooved, so I think you can put this one down to cheap knockoff parts