Voltage randomly dropping and passenger window issue

[Ant]

Both of these issues seem to have started together. Went to leave and as soon as I got going the passenger window was continuously going down and back up. Exactly how it would do when you open the door, drops down about a 1/4 inch and back up. It was doing this over and over again while driving until I pressed the button either up or down, but soon as I put it back up it would do it over again.

the voltage on the dash would also freak out. It would read anywhere from 13.1 to 14.0, but once I got on the interstate the window would stop going up and down and the voltage stayed at 13.5. As soon as I got off the interstate both issues came back.

All battery connections are tight. Alternator cable and plug tight. I even monitored voltage was wiggling every cable I could and nothing changed. I used my code reader and had U0140- missing communication with BCM and U0159- missing communication with parking assist module.

Sponsored

 

[MiamiGT350]

If a later model vehicle, it is normal for the voltage to fluctuate as the car smart charges the battery. I don't believe it is related to your issue.

Sounds like an issue with the door ajar sensor:

I cant speak to your error codes, but don't think they would cause the window behavior.

 

[ORRadtech]

I'd ask how old the battery is? Low battery voltage can cause all kinds of odd things in modern cars.
Having said that, I have read numerous threads about windows doing what you are describing. Perhaps search this forum or Google for those particular symptoms. I think you'll find several things to investigate.

 

[Ant]

The battery is less than a year old. After some more research I guess our alternators are “smart charging” and only charges when it’s needed. What I was seeing was normal I guess. Since I had weird things going on with the window and codes set I just paid more attention to the voltage gauge.

I will take a look into the window. I’ll have to pull the door panel. I forgot we had s very heavy rain the other night. It’s possible moisture got in somewhere it wasn’t meant to be.

 

[Rapid Red]

I think I've read there is a procedure to reset the limit switch home position, simple without taken things a part.
KISS first ....

 

[ORRadtech]

The charging strategy is quit complicated. A 1 y/o battery shouldn't be failing but if you're concerned most auto parts stores will load check it for free. When the current battery was installed was the computer reset so it knows the battery is new?
The window reset thing is what I was trying to remember earlier.

 

[Ant]

Yes I did a BMS after battery install.

I looked up the reset procedure so I’m going to try that today.

Sponsored