Battery light dimming headlights
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New User
Joined: Nov 2015
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Battery light dimming headlights
I have 2012 f350 with 6.7 diesel with 95000 miles on it never abused and well maintained just recently my battery light came on and off and now is on pretty much all the time except first bit from a cold start when it's on my headlights will flicker and dim and few times my heater controls have shut done but come right back on so far my batteries and alt are good anybody ever run across this??
Lead Driver
Joined: Mar 2013
Posts: 7,460
Likes: 85
From: Kent Station, WA
Probably better help in the 6.7 forum.
6.7L Power Stroke Diesel - Ford Truck Enthusiasts Forums
However I would start with getting your batteries and alternator tested. Also clean the battery terminals and apply some terminal spray.
6.7L Power Stroke Diesel - Ford Truck Enthusiasts Forums
However I would start with getting your batteries and alternator tested. Also clean the battery terminals and apply some terminal spray.
Fleet Mechanic
Joined: Nov 2011
Posts: 1,825
Likes: 43
From: Land of Taxes
Basic troubleshooting for the starting/charging system is:
Does it crank and fire OK? Yes...get it going then:
1. Read the running voltage at the batteries and at the alternator. 13.2-14.2 Volts DC?
2. Load test the batteries...pass/fail...fail replace as a set.
3. Remove, test and clean all battery cables down to the starter to include the solenoid.
4. Retest running voltage. 13.2-14.2 vdc? No...have the alternator bench tested and replaced/rebuilt. Inspect the serpentine belt and idler pulleys too.
A battery cable can visually look OK but be bad. Ohm test each cable. They should exhibit very low resistance.
Grounds are very important in these negative ground electrical systems in our vehicles. Clean and tighten, then spray battery protectant spray on all of the cleaned/serviced connections to keep them that way for a longer period verses not spraying them down. This includes all the smaller leads coming of of the large secondary (battery) negative cables. The starter mounting surface needs to be clean as well as any ground cable down at the starter.
Does it crank and fire OK? Yes...get it going then:
1. Read the running voltage at the batteries and at the alternator. 13.2-14.2 Volts DC?
2. Load test the batteries...pass/fail...fail replace as a set.
3. Remove, test and clean all battery cables down to the starter to include the solenoid.
4. Retest running voltage. 13.2-14.2 vdc? No...have the alternator bench tested and replaced/rebuilt. Inspect the serpentine belt and idler pulleys too.
A battery cable can visually look OK but be bad. Ohm test each cable. They should exhibit very low resistance.
Grounds are very important in these negative ground electrical systems in our vehicles. Clean and tighten, then spray battery protectant spray on all of the cleaned/serviced connections to keep them that way for a longer period verses not spraying them down. This includes all the smaller leads coming of of the large secondary (battery) negative cables. The starter mounting surface needs to be clean as well as any ground cable down at the starter.
Elder User
Joined: Jul 2015
Posts: 584
Likes: 1
I had a similar issue with my 99 5.4l recently. The light would come on, go off, come on, go off, blah blah blah. I found corrosion on the battery and cleaned it. That was a no go. Took the alternator off and had it tested, it showed fine. I kept driving and the light would come on more often and stay on longer. I took the alternator apart and tore it down. Found the brushes had worn a groove in the rotor and ever now and again it would cause an issue. It may not hurt to try a new alternator, and if that doesn't fix it you should be able to return it.
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