Possible alternator or wiper or connection issue
 

When I got into my very cold car (5F) in the morning, the wipers didn't work, at first. As the car warmed up I could get the intermittent setting to work but not slow or fast. As it warmed up more it started to work normally, sort of. I noticed that engine RPM had an impact. I also noticed that whenever I push the wiper fluid button, the wipers ALWAYS start immediately. To me, this sounds like an issue with the wiper controller but it could still be a an alternator or connection problem.

The battery is only a year old but when I left it at the mechanic for 2 weeks to get the wheel bearing and coil pack done while I was on vacation, the battery got too weak to start the car. Was it the 2 weeks in the cold or was it just not charged enough due to an issue, who knows?

I connected my PC to the SSM and monitored the ECU voltage on my 20 minute drive this morning. When cold, and nothing on, the voltage was 13.9-14.0V. When I started driving I turned on the rear defroster and I saw that the voltage stayed between 13.8 and 14.0V on the whole drive. When I stopped the voltage was still between 13.7V and 13.8V at idle. The defroster was off at this point. I turned on the headlights and the voltage dropped to about 12.5V. I turned the defroster back on and the voltage dropped to 11.9V.

Do these voltages seem reasonable? I checked the battery terminals and they seemed pretty clean and tight.

If it is the alternator, has anyone tried the alternator below for an extended period of time an/or miles?

https://www.amazon.com/dp/B007XUI7D2...v_ov_lig_dp_it

http://www.subaru-svx.net/forum/atta...1&d=1579793593

Re: Possible alternator or wiper or connection issue
 

For the temperature those numbers seem about right. I like to see 14.2 to 14.3 volts. Cold does nasty things to a car.
When your car is running the inside gets nice and warm, also humid from all the melted snow on the floor. As it cools down at night all this moisture condenses and freezes on everything including connections and switches and of course the windshield.

Re: Possible alternator or wiper or connection issue
 

It is in the 20s this morning. Will see how they work today. I may try simply cleaning the connectors first.

Well, still did it in the mid-20s. Electrically, everything seems to check out in the car. I am suspecting the module and connectors.