charging issues
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Senior User
Joined: May 2007
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charging issues
Start truck and voltage climbs to 12.5 at idle. Driving down road voltage climbs to 13-13.7. Within a couple of miles voltage drops below 12 and battery light comes on. I have load tested batteries they are good. Bench tested alternator by my starter and alternator builder. That tested good after 10 minutes of loading it. It was nice and hot and I replaced the belt. Any ideas?
Hotshot
Joined: Dec 2003
Posts: 15,369
Likes: 121
From: Stuttgart, Ar
The ECM doesn't control alternator output unless you have dual alternators and it only controls the second alternator. The alternator is controlled by the Hybrid Electric Cluster. Check the plug-in on back of the alternator. The wire can break internally and cause a battery light. Saw one last week.
Lead Driver
Joined: Feb 2011
Posts: 8,241
Likes: 155
From: L.A. (Lower Alabama)
Here's a print might be some help if you are handy with a meter. I'm on a cellphone not sure if link will work.
https://www.ford-trucks.com/forums/p...ictureid=67445
https://www.ford-trucks.com/forums/p...ictureid=67445
Lead Driver
Joined: Feb 2011
Posts: 8,241
Likes: 155
From: L.A. (Lower Alabama)
I haven't had to chase those down before but it looks like ther are two somewhere near the passenger side battery and another in the harness behind the alternator. I posted the print in agreement with partsman so you could identify the "I" circuit LG/RD (light green/red stripe). IRRC the batt light has power not shown on print and is turned OFF when power is present in the I circuit. Be sure to note connection at back of alt as well as inside alt housing.
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 26
From: Middle Tn.
Start truck and voltage climbs to 12.5 at idle. Driving down road voltage climbs to 13-13.7. Within a couple of miles voltage drops below 12 and battery light comes on. I have load tested batteries they are good. Bench tested alternator by my starter and alternator builder. That tested good after 10 minutes of loading it. It was nice and hot and I replaced the belt. Any ideas?
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Mountain Pass
Joined: Nov 2005
Posts: 164
Likes: 2
From: Cloverdale VA
I have been having this exact problem for a while now. Right down to the voltage dropping after driving a few miles, then climbing back up to around 13.3-.7. Just this past weekend the light became constant. I ordered a DC power alternator Monday. Let you know how that works out.
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Hotshot
Joined: Dec 2003
Posts: 15,369
Likes: 121
From: Stuttgart, Ar
I think it's an internal problem in the alternator either with the slip ring or the brush/regulator assembly. I went through this on my daughter's Escape 4 times and it's been the alternator every time. The springs break in the brush assembly and make intermitent contact on the slip ring. Replaced the assembly and problem solved.
Mountain Pass
Joined: Nov 2005
Posts: 164
Likes: 2
From: Cloverdale VA
Follow up. DC Power alternator arrived today. Bolted right on in minutes, plugged into factory wiring and no more problem. Paid about the same, including shipping, as a chain store chinese rebuild. Instead got a brand new, assembled in US(not sure where all the parts are made) higher than stock output unit and got to keep the core as well. I will try and repair it as a spare. Best of luck in the repair just thought I'd share my experience with the same issue.
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Nov 4, 2016 07:50 PM