Overvoltage problem

[B2C2]

Hi Jon. You don't say what year your plane is. Mine is a 1969. On that plane, I have replaced the regulator selection switch several times. This switch can degrade over time, and when this happens, the resistance in series with the regulator input causes a voltage drop that causes the regulator to overshoot the correct operating voltage. One symptom of this is that toggling the switch will typically cause this to settle a little bit, however its not a fix. Generally, the resistance of the path from the system buss to the regulator sense input must be low. Any issue with this, most likely the switch, but can be caused by poor crimps etc. will cause the system voltage to creep up and show instability.