Interesting voltage change

[hayesbd]

I just replaced my voltage regulator (mechanical type) with an electronic one. The voltage is a bit more stable with less radio noise. However, the behavior I noticed with the mechanical regulator still exists with the electronic one: when I step on the brake, the voltage rises from the usual 14.1V or so to 14.5 or even sometimes up to 14.9V. This happens only with brake lights - all other power loads either don't affect the voltage or drop it slightly as would be expected. Does anyone else have this issue? I can't think what might cause this other than a floating ground, but the lights are bright and work well...

Brian

[seabeelt]

Check the grounds with your tail lights. Sounds like the voltage is trying to overcome resistance to make the lights work
R/

[TX82FIAT]

Typically if the bulb or the socket have excess corrosion the light will stop working. However, I would see if a good cleaning and a fresh bulb help reduce the possible increased resistance pushing up voltage. Using Ohms law it does not take a whole lot of additional resistance to bump voltage up .5 volts. On the cars i have owned they share a common ground for the tail lights in the trunk. While cleaning that ground is always a good idea, i would think that you would see other lighting voltage issues if it is the common ground. Example, voltage flux when you turn on the turn signals or put the car in reverse.

See if cleaning the brake light sockets and/or putting new bulbs in helps as well as checking the connections to that circuit. Not sure if you mentioned what year car you have. The later models have that circuit board that has connectors for wiring harness to connect to the circuit board. These connection points can get corrosion or poor contact as well increasing resistance and increasing voltage required to bring the lights on. About every two-three years i clean the contacts points and sockets.