Alternators & Regulators - BOSCH: Testing: Adjustment
If voltage reading is out of limits, remove regulator cover and adjust voltage regulator armature spring tension to obtain a middle reading of 14.0 volts. If reading fluctuates, voltage contacts are dirty. Replace regulator cover and recheck voltage setting. A steady voltage reading between 13.5 and 14.5 volts indicates regulator is in good condition.