Alternator failing and no brake lights

[Blondski]

I have a 2003 Explorer 4WD 4.0. XLT
Battery light on.
OBD2 states alternator low voltage.
Explorer starts.
Cannot get shift lever out of park.
Do not have brake lights.
Is it possible to have alternator and brake light switch problem or could it be a relay that would affect both?
Scanned several threads but couldn’t find this.
Thank you in advance!
K

 

[sweetbeats]

I have a 2003 Explorer 4WD 4.0. XLT
Battery light on.
OBD2 states alternator low voltage.
Explorer starts.
Cannot get shift lever out of park.
Do not have brake lights.
Is it possible to have alternator and brake light switch problem or could it be a relay that would affect both?
Scanned several threads but couldn’t find this.
Thank you in advance!
K

What voltage do you measure at the battery when the motor is running?

 

[DaaQ]

I have a 2003 Explorer 4WD 4.0. XLT
Battery light on.
OBD2 states alternator low voltage.
Explorer starts.
Cannot get shift lever out of park.
Do not have brake lights.
Is it possible to have alternator and brake light switch problem or could it be a relay that would affect both?
Scanned several threads but couldn’t find this.
Thank you in advance!
K

I am having almost the same issue, alternator is NOT charging the battery, 2 different alternators also.

Shift lever can be tied to low voltage, but battery should be very dead. Most likely is its just wear and tear, mine is difficult to get into out of park at times.

 

[Blondski]

What voltage do you measure at the battery when the motor is running?

It’s at 13-14 upon start but goes down pretty quick if I use anything that will drain it.
Scanned w OBD2. Alt issue

 

[sweetbeats]

It’s at 13-14 upon start but goes down pretty quick if I use anything that will drain it.
Scanned w OBD2. Alt issue

How far does it drop when you turn something like your headlights on?

If you know the charging system can’t keep up, and your code scanner verifies that, I would start by taking it to your LAPS and having them test the alternator, replace if bad, and see if the problem remains. The alternator could be delivering 13-14V with little load, but as soon as there is demand it can’t provide the current and the voltage drops. So I’d start there. I’ve not studied the electrical schematics for the Explorer yet, but if there is any logic circuitry involved in the transmission shifter or other functions you mentioned that are being wonky, logic circuitry can do really weird and unpredictable things when the voltage drops below a minimum threshold. So if your system voltage is low enough, all bets are off as to what might happen.

 

[BrooklynBay]

Did you remove the ground wire to clean the terminal connected to the body (not the side connected to the battery)?