perfectly normal for battery volts to drop as you load more current w accessories turned on. google v=ir equation in a physics lecture
when the alt is running, the regulator keeps the volts steady around 14-14.5vdc
my blinker always causes my fuel pump to hum in rhythmic iscillation as my blinker goes now that i think of it. must be a response time thing on the regulator built into the alt.
turn ur headlights one at idle, engine slows, then speeds up again as the regulator corrects for amp draw
i replaced my oem alt last year w another lower mileage denso oem 1987 alt. my fuel pump still hums the same when blinkers run at idle. i still have the original 260k fuel pump in the car. if u have an aftermarket, or larger pump, it will draw more amps and i’d assume the humming oscillation would be more noticeable
when working on my other cars, i notice after cleaning the fuel pump filter sock in the pump, not the tank, the humming quiets down
suggest u start another post on the other electrical issue ur having. purpose of this post was to highlight the strange issue noticed as a light bulb was on verge of failing. i recall reading consumer reports years ago. they rated electrical system on these cars to be poor. i’ve not had any unnormal issues w this car since 1993 up until now
keep us posted if u figure it out
Definitely agree with you here. The only thing is that it seems to be much more dramatic on that specific circuit. There are a few interesting things I have discovered since. While I do get voltage drop with any added load it is much more pronounced when using the turn signals and reverse lights specifically. Looking at the fuse panel they share a fuse. The other interesting thing is that when I turn on the hazards they do not cause the significant voltage drop that the turn signals do. Considering they use the same lights and relay thats a significant detail. Just looking at that it seems like the uncommon denominator would me the multifunction switch. The other thing I didnt really consider was that the fuel pump itself might be the thing that is putting the high load on the system and the signals might just be putting it over the edge. I have since changed out my fuel pump for a new Bosch unit and the difference has been mind blowing. I can no longer even hear the pump turn on when I flip the key in the morning. The only reason I know it has turned on is because the new pulsation damer I installed on the pump vibrates with the initial burst of fuel. There also seems to be less of a load on the system but I have yet to actually verify that. I can say that I no longer hear or see any effect on the car when the signals are on though maybe still a slight difference in idle stability which I am still trying to sort out.