Battery light on
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From: Moyock
Battery light on
I have a 1999 Ford F150 6 cyl. 4.2, 2 WD with 160,000 miles. Replaced the battery May 2010.
Today battery light came on. Battery gauge did not look like it was discharging.
Had battery checked they said it was a little low but OK. Then they continued test and tried to check alternator, test stopped and they said something wrong with alternator most likely.
I took alternator out and had it bench tested. They said it was OK, putting out 98 amp on 95 amp alternator. They said check wires, grounds, harness, connections. Checked connections and wires as much as possible, reinstalled alternator, light still on.
Have not checked fuses yet.
Was told to start vehicle, disconnect positive battery cable and if engine continued to run alternator was good, if cut off alternator was bad and to replace. Should I try this and is it true?
What is the part on the fire wall that is between the alternator and the battery that the wire connection runs through? Can it be bench tested/checked?
Today battery light came on. Battery gauge did not look like it was discharging.
Had battery checked they said it was a little low but OK. Then they continued test and tried to check alternator, test stopped and they said something wrong with alternator most likely.
I took alternator out and had it bench tested. They said it was OK, putting out 98 amp on 95 amp alternator. They said check wires, grounds, harness, connections. Checked connections and wires as much as possible, reinstalled alternator, light still on.
Have not checked fuses yet.
Was told to start vehicle, disconnect positive battery cable and if engine continued to run alternator was good, if cut off alternator was bad and to replace. Should I try this and is it true?
What is the part on the fire wall that is between the alternator and the battery that the wire connection runs through? Can it be bench tested/checked?
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From: Virginia
No No No, don't pull the battery cable off with the engine running. It may quit and never run again. That's an old school way to see if a generator was charging when the old cars didn't have any electronics. It's too risky on the newer vehicles, and even a older vehicle with a nice radio can have it blow up by doing that.
The newer trucks do have fuses for the regulator. Check all the fuses in the underhood fuse box, I believe it has one for the regulator.
The newer trucks do have fuses for the regulator. Check all the fuses in the underhood fuse box, I believe it has one for the regulator.
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as dave said, don't try pulling the cable while running.
along with inspecting fuses, you can also test for power at the plug that goes into the regulator. the 3 wires of that plug are identified as A-S-I with the letters being present on the regulator where they plug in. wire A should have battery voltage at all times, wire S should have continuity to the 1-pin connector next to it, and wire I should have power when the key is on. power for it goes through the ignition switch, idiot light, and down to the alternator there.
along with inspecting fuses, you can also test for power at the plug that goes into the regulator. the 3 wires of that plug are identified as A-S-I with the letters being present on the regulator where they plug in. wire A should have battery voltage at all times, wire S should have continuity to the 1-pin connector next to it, and wire I should have power when the key is on. power for it goes through the ignition switch, idiot light, and down to the alternator there.
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From: Moyock
No luck with the issue being just a fuse, checked all fuses inside and under hood. Not sure about any relays of the battery cable fuse link.
Is it possible for the alternator to be bad even though it bench tested OK?
Is it possible for the alternator to be bad even though it bench tested OK?
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Joined: Jan 2001
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From: Virginia
When it bench tested ok, the regulator and the alternator passed.
Here's a schematic.
http://repairguide.autozone.com/znet...52801e5707.gif
With the key off, make sure you have battery voltage on the large output terminal.
When the engine is started, make sure you have voltage on the lightgreen/red wire.
You can see 3 fuses in the diagram for this alternator.
Here's a schematic.
http://repairguide.autozone.com/znet...52801e5707.gif
With the key off, make sure you have battery voltage on the large output terminal.
When the engine is started, make sure you have voltage on the lightgreen/red wire.
You can see 3 fuses in the diagram for this alternator.
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