Battery/electrical issue

2004 FORD F-150
160,000 MILES • 4.6L • V8 • 2WD • AUTOMATIC
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STEVENDUKIC
  • MEMBER
  • 1 POST
Hello, I'm been having several electrical/battery issues and am at a loss as to what to do next. Here's the chain of events:
- Truck started idling rough at stop lights. Took to local mechanic. He replaced PVC valve, fuel filter and spark plugs. Idling issue resolved.
- Alternator went out two days later. Replaced that myself. Car drove fine the next day on a 2 hour drive, however, the battery light kept coming on and off while driving.
- Truck loses all power and breaks down on the side of the road. Went back several hours later and battery had recharged. I was able to get it home just as the battery was dying and the dash was going dark.
- Took battery to be tested. Passed all testing, however they did say it was in it's last quarter of life (??)
- Found the metal connection of the positive battery cable was cracked/damaged at the terminal connection, likely when I was replacing the alternator. Bought a battery cable repair kit, replacing the terminal connection.
- Car appears to run okay, but I haven't tested it for a long duration (trying not to get stranded a third time)
- The battery light keeps coming on and off. When the truck is driving, battery light only comes on randomly, mostly when slowed down. The battery light stays on when idling.

To summarize: new alternator, new battery cable, battery passed testing. Battery light staying on when idling and randomly coming on/off when driving.

Please help!
Aug 24, 2019 at 2:18 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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SCGRANTURISMO
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 4,897 POSTS
Hello,

This could be a problem with the serpentine belt tensioner. If the serpentine belt is glazed, cracked, or loose because of the tensioner not holding the proper tension on it then the alternator will not spin as it should and it will have lowered current output, especially when the vehicle is at an idle. In the diagrams down below I have included a factory guide for the inspection of the serpentine belt tensioner for your vehicle. Please go through this guide and get back to us with what you find out.

Thanks,
Alex
2CarPros
Aug 26, 2019 at 3:21 AM
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