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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6213
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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Ford f150: battery keeps going dead. but it will charge back

Customer Question

battery keeps going dead. but it will charge back to 100% on charger but it just wont hold. I disconnected pos cable and put a 12 volt light tester between pos side of battery and the cable. Light comes on. I'm thinking a short somewhere.
Submitted: 1 year ago.
Category: Ford
Expert:  A. Penland replied 1 year ago.
Hello and thanks for using JustAnswer.I will try my best to help you with your question.
You have what is called a current draw. Make sure the doors are closed and the ignition is turned off and the key is removed before doing the test.
Also, use a digital multi meter and set it to DC AMPS and place it in the same position a the test light and check the amp draw. It should only be 0.005 miliamps or lower. If it is higher, you will have to remove the fuses one at a time and see if the draw goes away and then reinstall it and go to the next one.
Customer: replied 1 year ago.
I already removed each fuse under the glove box one at a time and the light never went out. I did not use my meter.
Expert:  A. Penland replied 1 year ago.
Do you have the new body style or the heritage body style?
Ford made both in 2004.
Customer: replied 1 year ago.
I'm not sure what the difference is. It is different from my 99 light duty f 250 ( looked the same as the 150. the vin number is *****
Expert:  A. Penland replied 1 year ago.
Ok. That is the new body style.
You have the 5.4L three valve engine.
Do the tests with the meter on AMPS and unplug the alternator. You may have to start unplugging the modules. There is one large connector on the top of the dash fuse box. This wire powers up the dash fuse box and everything the dash fuse box powers up. You will have to unbolt the dash fuse box to get better access to this connector. It has a large red wire going to it.
Customer: replied 1 year ago.
Is it possible that the cable feeding the fuse box has a short?
Expert:  A. Penland replied 1 year ago.
No. If the cable was shorted, you would have a burnt fuse. You have something either staying powered up or the battery is actually shorted inside.
Customer: replied 1 year ago.
Ok. I need to go to work so I will need to try this tomorrow.
Expert:  A. Penland replied 1 year ago.
No problem. Reply back when you can.
Customer: replied 1 year ago.
I changed out the batter with my other truck and have the same problem. I stated removing connectors from the fuse box and got the light to go out. Meter was reading .012 amps. I started adding back the connectors and light comes back on. Can't find a wiring diagram online to see wiring diagram.
Expert:  A. Penland replied 1 year ago.
What connector did the most change?
Customer: replied 1 year ago.
It was one ne the back. But I think it may just be the way it's wired because I got other connectors to make the draw stop as well.
Expert:  A. Penland replied 1 year ago.
Did any of the fuses change the draw?
Customer: replied 1 year ago.
None of the fuses caused my test light to go out. I didn't test the draw after pulling every fuse.
Expert:  A. Penland replied 1 year ago.
The reason I ask is that there are several circuits in each wiring connector.
You will have to do the current draw test for each fuse. The problem is inside the vehicle and not under the hood.
Customer: replied 1 year ago.
Is the fuse box the best or only place to work from?
Expert:  A. Penland replied 1 year ago.
The fuse box is the best place to work from. Current draws are not easy or fun to diagnose. They do take patience and time.
Customer: replied 1 year ago.
Great. Back on it tomorrow
Expert:  A. Penland replied 1 year ago.
Ok.

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