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Drove the truck 1/4 mile from home. Noticed red battery light on the dash. Returned home. Measured battery. 12.5V without engine running, 12.2 with engine running. OBD2 says 11.8V. Please confirm the alternator is bad. The rebuilt alternator is a few years old. Thank you.
Alternator not necessarily bad, what you do know is that it is not charging. Voltage drops because the battery is now being used to run truck.
To start, check the connections for looseness, poor terminals and corrosion.
OBD2 says 11.8V. Please confirm the alternator is bad. The rebuilt alternator is a few years old. Thank you.
While it is important to do proper diagnostics I'll go out on a limb and say the rebuilt alternator is going to be the problem. Often "rebuilt" only means fix what's wrong with it, clean it up and send it out. It doesn't mean they replace everything inside of it.
Wiring and fuses checked out ok per https://easyautodiagnostics.com/ford...imeter-tests-1. Removed the alternator and found worn out brushes. I am going to see if a new set of brushes will solve the problem. This rebuilt alternator has about 10K miles. I guess the re-manufacturing shop just replaced the brushes, slip ring, and bearings with the least expensive parts.
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This rebuilt alternator has about 10K miles. I guess the re-manufacturing shop just replaced the brushes, slip ring, and bearings with the least expensive parts.
If they replaced them at all, those could be the originals.
I think you are right. Brushes wearing down to short stubs in 10k miles don't make sense.
In my navigator the battery light was coming on and off randomly. With a new alternator being close to $600 I instead took it apart, cleaned the slip rings, replaced the brushes ($15), then put it all back together. I installed it and haven't had a problem with it since. This is what most rebuild shop do, so if for example they did the same as me, a bearing or the diode pack could've went out 2-months later. This is why I almost never buy rebuilt, only new.
Bought a rebuilt regulator+brush assembly and installed it. No more red light on the dash, charging voltage 14.2 per obd2. Thank you for your advice.
While the belt was off, I checked the idler pulleys. Noticeable free play though not squeaking. I had 6203 sealed bearings left from previous repairs. Replaced both bearings. Ball joint remover came in handy.
Glad you got it. I came out the other morning and my 850 amp. newer battery was so dead it would not even unlock the door. Stuck my smaller Mustang battery in it that was being stored in the basement for winter and it fired right up. Put a meter on the battery and it was getting 19.5 volts.....never seen that before. Shut it down and pulled the 18 month old alternator out and took it back to NAPA. Lifetime warranty so walked out with another one at N/C. It didn't ruin the original battery, but man, that is a lot of volts. Finding a good alternator these days can be hard.
The battery has been fine, started the other day at -27 below but cranked slow. Had it plugged in but I checked the plug and had a wire broke. Fixed that, factory block heater ohm'd at 25 so that is all good again. But yeah...that was some scary voltage. Even the guy at NAPA was like....holly sh** bring that back and get another one.
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