Battery Light Issue

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Jun 17, 2011 | 01:32 PM

FoundOnRoadDriving85

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Joined: Mar 2010

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Battery Light Issue

Ok so I've been having a problem with my 99 expedition. It has a 5.4 btw. The battery light had been coming on then going off, but this morning it came on and stayed on. My fiance started wiggling wires (b/c both alternator and battery are less than 6 mo old) when nothing changed he unplugged the plug by the solenoid along the firewall.....the batt light went off. Thing is we don't know what the plug is for. Everything still works. Only thing that changed was the batt light went off. So, what does the plug go to?.......Thanx in advance

Jun 17, 2011 | 06:14 PM

High_Horse

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Joined: Jun 2004

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From: Orlando, Fla

If its the top wire with the 'L' shaped connector, that's the signal wire from your ignition switch. Check it for scarring or a break in the wire, it sounds like its shorting.
I am more suspecting of the voltage regulator. I don't care how old a part is, I've pulled new ones out of the box bad or go bad shortly thereafter. Double check the battery connections at both ends. Voltage is very important to ODBII systems.

Jun 18, 2011 | 12:26 PM

TenHoles

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Joined: Mar 2009

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There is a 1 wire connector on top of the alternator that is easily accessed if you take the intake tube off. disconnect that wire from the alternator. inspect the connector and terminal on the alternator for corrosion and inadequate clamping force. If need be replaced that connector with an appropriate spade type terminal.

That should take care of your batt light problem. I just repaired that on mine about 3 months ago. No problems since.

Just to rule out the bad alternator, simply check voltage at the battery with the truck running. should be 13.8-14.2