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Help alternator not charging!!!

14895 Views 11 Replies 6 Participants Last post by  330kstrong
Alternator went bad and put a new one on and I'm getting 11.25 volts outta it. Now the alternator on a bench test shows it's working fine. The problem I'm having is I'm not getting any power thru the two wire plug that ignites the alternator. I ran a jump wire of the plug straight to the battery and it worked fine. I also changed the mega fuse. Can anyone help me?
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How old is the battery? I've seen a bad battery make it seem like the alternator was pooched before while I responding to roadside assistance calls...
Check the grounds points. At the battery, where the battery negative cable attaches to the body and the ground on the left side of the block, above the engine mount.
I've had the truck about a year and it was the battery in the truck when I got it. It holds a good 12.07 volts when unplugged but that don't mean it's good. And I'll check all the grounds and get back to you guys thanks so much!!
All grounds are good I even ran a ground from the body on the alternator straight to the neg on the battery and still no power from that plug
Could be a bad alternator, I bought 2 new ones from Autozone to find out they were both bad. Ended up rebuilding mine for half the price from a shop down the street from my house.
If I jump a wire from the alternator to the battery it charges fine. I put a scanner on it and it's throwing a p0622 generator f-terminal circuit code
I suspect you have a shorted wire between the alt., and the PCM. You need to check your wiring harness for bad wires, or rubbed through wires.

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DTC P0622
Circuit Description

The powertrain control module (PCM) uses a generator field duty cycle signal to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding ON and OFF. The PCM uses the PWM signal input to determine the generator load on the engine. This allows the PCM to adjust the idle speed to compensate for high electrical loads.

The PCM monitors the state of the generator field duty cycle signal circuit. When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5 percent and 100 percent. The PCM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the PCM detects an out of range PWM signal, DTC PO622 will set. When the DTC sets, the PCM will send a class 2 serial data message to the instrument panel cluster (IPC) to illuminate the charge indicator.
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I couldn't figure it so I cut the red wire and ran my own fusible link from the power windows terminal and called it a day. Thanks guys
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