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Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 23591
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Chevrolet K2500 4x4: 2001 chev not chaging new alt no power

Customer Question

2001 chev not chaging new alt no power to the 2 wire plug
Submitted: 1 year ago.
Category: Chevy
Expert:  Dan replied 1 year ago.
Hello, my name is ***** ***** I'm here to help get your problem solved. The small 2 wire plug should not have power. Does the large wire going to alternator have battery voltage with engine off?
Customer: replied 1 year ago.

yes

Expert:  Dan replied 1 year ago.
Check the Brown wire for 10 volts when the engine is running and the alternator disconnected. This is the turn on signal for the alternator. Brown wire comes from pin 15 of connector 2 at ECM. So if no voltage on brown wire check to see if wire is broken/damaged between ECM and alternator, if not replace the ECM. Let me know how it goes or if you run into questions, thanks.
Customer: replied 1 year ago.

a little over 10 volts

Expert:  Dan replied 1 year ago.
It sounds like new alternator may be problem. Bypass the vehicle wiring by connecting a test light to B+ and connect to the alternator where the Brown wire is normally attached. If the test light comes on and the alternator quits charging, replace. You can also verify case ground is good and check the Gray wire from the alternator terminal C to the Powertrain Control Module (PCM) connector C2 terminal 75. Let me know how it turns out or if you have more questions, thanks.