86 535i flickering lights

[arth]

About a year ago the headlights, etc. started flickering and progressively got worse regardless of the rpm. So I replaced the alternator with a new Bosch unit from Pep Boys. The flickering stopped. Now it has started again, but only at idle rpm (700 rpm). On an increase in rpm the flickering stops at about 1000. The flickering is not affected by the electrical load; in other words, the interior lights flicker even with headlights switched off. Is this an indication that the alternator/regulator is going bad? What is the procedure for checking the alternator? Or might there be another problem with the electrical system? Thanks in advance.

[Jeron]

I would check the voltage at various locations. My guess would be the voltage regulator.

[arth]

Thanks for the input, Jeron. The voltage regulator is attached to the alternator and came with the new alternator. Therefore, I will return the alternator/regulator to Pep Boys for a replacement. It's supposed to have a lifetime warranty.