Hard downshift / electrical

[Simsy]

I have an 09 expedition. Tonight I noticed that my interior lights are dim and voltage is not as high as it should be. I'm thinking bad alternator but possibly bad battery. My question is can this cause hard downshifts with the transmission ? specifically coming to a stop shifting into 1st

 

[Simsy]

I also noticed that my dash flickered when I first start the expedition and my radio doesn’t light up

 

[2020-MAX-Limited]

Doubtful it would affect transmission downshifts. As far as your electrical questions, most vehicles will show a warning light for low battery (amber typically) and alternator issues (red normally). Alternator being more critical is shown in red so you will address it with more urgency. Low battery voltage is not as critical so is shown in amber. A simple device like this plugged-in to your 12V outlet can show you the health of battery (read with the engine off) and alternator/charging (read with the engine running).

 

[Simsy]

Doubtful it would affect transmission downshifts. As far as your electrical questions, most vehicles will show a warning light for low battery (amber typically) and alternator issues (red normally). Alternator being more critical is shown in red so you will address it with more urgency. Low battery voltage is not as critical so is shown in amber. A simple device like this plugged-in to your 12V outlet can show you the health of battery (read with the engine off) and alternator/charging (read with the engine running). View attachment 72219

My voltage gauge fluctuates Too much. With heat on / rear defrost and head lights the gauge is down to the point where the battery light is just about to flicker …

 

[Motorcity muscle]

Need to get a voltage reading like mentioned, low voltage will cause all kinds of issue's. Including transmission shifting, computers are very sensitive to voltage.

 

[Trainmaster]

If your battery light is flickering, something's wrong. Follow Muscle's advice. Low voltage can affect shift quality.

 

[Simsy]

UPDATE: today when switching to 4x4 the instrument cluster flickered off and on … then the wrench light came on , traction control started flashing and I believe the Abs light illuminated . Any suggestions?? This also caused trans to stay in 3rd gear (limp mode)