Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 2008 ford expedition with 5.4 customer says hes's changed 3 alternators. now he brought it to me I looped Gen com and Gen mon wires and commanded output and my Gen mon is following so i have to believe the harness is fine. while running scanner shows a Gen command of 55 and Gen monitor of 100 Gen frequency on 00 and battery volts is 11.2 volts Any thoughts ?????
those systems are the smart charging system. to determine if its a control issue or alternator issue unplug the harness rev the motor to 3000 rpm a couple times. the system should default to 13.5 volts if the alternator is working...
Good move jumpering Gen-Com and Gen-Mon together. From here, I'd do as Cheryl suggested. If you don't see 13.5V, then it's still a bad alternator. Consider using a Motorcraft new or reman, if the owner hasn't already.
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