Voltage Spiking

[Dads TJ]

Lately I have noticed my voltage spiking, at times maxing out the gauge. When the gauge max's out the radio lights and the odometer lights go out til the voltage returns to a normal level. Assuming this is an overload protection. Also when the voltage is rising above 13 volts the headlights dim.
Is this a voltage regulator issue or the alternator, or is the regulator in the alternator. Also, replaced the battery 3 weeks ago because the old was not holding a charge.
Only seems to do this when the headlights are on.
New to Ford, so any help would be great.

2003 Expedition XLT 93,000 miles 4x4 5.4 eng.power everything no after market radios, speakers, amps,. etc. So the harness has not been butchered. Completely stock

Offered as much info as I thought might be necessary to help diagnose the problem.
Thanks, Troy

 

[corlon]

sounds like the regulator in the altenator is weak or bad. may have killed your old battery. a lot of vehicles are voltage sensitive now rather then current sensitive. you can check all your grounds under the hood, but i think you'll need a new altenator or have yours repaired.

 

[ssbroly]

Sounds like the alternators shot. Run it up to your local auto parts store. They will check the charging system for free. Mine did the exact opposite. And in my opinion, skip the remanufactured junk and just get a brand new one.

 

[Dads TJ]

Hey guys, Thanks
I was leaning that way initially, but wanted some Ford advice, it belongs to my GF, I am a Jeep guy (Rock Crawling)
Again, THANKS

 

[ohillny]

DOES any know what the voltage should be for the 2000 Expo I just put in a new alternator and it charging at like 15.05 volts. I put in a new because my battery light came on and I tested it battery was at 12v and some change and the alternator was at 14.4 and higher when i put a load on I was told it was over charging. But since putting the new one on and seeing the volts go up I dont know, but the battery light did go off..

 

[stamp11127]

At our bus shop the upper limit is 14.5 volts @2000 rpm's. I would worry about the 15.05 reading and double check with a second meter.

 

[Thermo]

ohillny, I would say to take your truck to a local auto parts store and tell them that you are getting strange readings from your alternator and see what their machine says. Most multimeters are not calibrated and can give false readings. The testers at the auto parts store are going to have a calibration done on them. If your truck is putting out 15 VDC, then you run the risk of hurting the electronics inside the truck due to too much voltage. If this is the case, then I would check to make sure that the voltage sensing line does not have any high resistance connections in it (tan wire going to the alternator) as this is what controls the output of the alternator. If you see a difference between the voltage on this wire and the voltage across the battery, then you have a bad wire and you need to run a new wire to correct your problem.

If you need more help, let me know.

As a side note, I am going to be up in Rochester in October to do some work at the nuke plant up there. Maybe we can get together some time.

 

[wseand]

I have a similar problem, my gauge starts out in the middle then raises to max, in the red, 5 secs after starting. New Battery and Alternator, I am getting good voltage to the battery 14 on the Voltage Meter.

I was getting the voltage spike on the Gauge with the old Alternator and after I replaced it.
New Duralast Alternator put in today.
What could cause the gauge to read so high if i am getting good voltage off the battery and a new battery and alternator.

I was trying to find the Regulator fuse but couldn't figured out which one it was, any ideas?

2007 Expedition