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Hello,The battery light is controlled by the internal voltage regulator and in most cases its comes on when the alternator/regulator has failed or the connection to the regulator.Disconnect the alternator to verify the light goes out proving the Light Green/Red wire is not shorted to ground in the harness. If the light is still on, locate and repair the short to ground in the harness. If the light does go out, at the alternator with everything connected and the engine running, check the voltage on the Orange/Light Blue wire in the 3 wire connector at the alternator looking for full battery voltage. If the voltage is low on that wire, locate and repair the voltage drop in the circuit. Start with checking for a problem at fuse #11 20A in the engine compartment fuse box. If the voltage on the OG/LB is good, check the voltage on the White/Black wire in the 3 wire connector looking for half of system voltage with the alternator charging. If the voltage is correct, inspect the connections at the 3 wire voltage regulator connector. If the terminals are all good and tight, suspect a faulty regulator in the alternator.