So, this has happened to me twice in the last week. Both times I'm on my way to work in the morning, sitting at a stop light, idling with my foot on the brake, and the car makes a weird singular jerk forward as if something is kicking on and the voltage drops from its normal 14.5-ish volts to about 13 volts for a couple seconds and then goes back to normal. This is with the AC/Heat turned OFF so it shouldn't be the AC compressor kicking in. I initially thought maybe the fan was kicking on, but I wouldn't think that would cause it to jerk like that and cause the voltage to drop like that, plus it never does it any other time when I'm in traffic when the fan should be kicking on and also, by this point in the morning the engine is nowhere near normal operating temperature yet. I'm kind of at a loss on what could be causing this. Both times were about a week apart as well which makes it more confusing. Could it be an intermittent issue with the ABS?

 

Unfortunately, it is a bit challenging without experiencing it or more information (and I am not sure the information to ask).

 

Yes, it's an odd one. Just seems to happen every few days and only at idle while stopped at a light or stop sign and only once no matter how many stops I make on the way to wherever I'm going. It's not causing drivability issues at this point and I'm not overly concerned so I guess I'll just deal with it as a quirk of a higher mileage older car.